Everyday Life & Household 9 calculators
- Sale Price & Discount CalculatorFTC Guides Against Deceptive Pricing (16 CFR 233)Enter what you know and this calculator fills in the rest of the deal. Give it an original price and a percent off — plus a…
- Self Storage Unit Size CalculatorNFPA 13 sprinkler clearanceStorage units are rented by floor area but filled by volume, so the number you need is cubic feet divided by the height you can…
- Shelf Spacing Calculator32 mm cabinetmaking systemEvenly spaced shelves are not the opening height divided by the number of shelves — the shelves themselves take up room…
- Split the Bill CalculatorEven-split arithmetic with largest-remainder penny allocationEnter the check subtotal, the sales tax rate, the tip you want to leave and how many people are paying, and this calculator…
- Square Foot Garden Plant Spacing CalculatorSquare Foot Gardening grid method (Bartholomew)Give this calculator a bed size and the spacing on the seed packet and it returns how many plants fit in one square foot, how…
- Stacked Coupon & Double Discount CalculatorMultiplicative discount compositionPercentage discounts never add. Take 40% off and then another 10% off and you have paid 54% of list, not 50% — the second…
- Streaming Data Usage CalculatorIEC 80000-13 decimal GBStreaming data is not a mystery: it is bitrate multiplied by time. This calculator converts your viewing hours and chosen…
- Streaming vs Cable Cost CalculatorTotal cost of ownershipA cable package price is roughly half of what the television part of your bill costs. Box rental, DVR service, a regional…
- Subscription Cost Audit CalculatorFuture value of an ordinary annuityRecurring charges are designed to be invisible: each one is small, each one renews silently, and no statement ever shows you…
Investing & Retirement 8 calculators
- Safe Withdrawal Rate CalculatorBengen (1994) and Trinity study frameworkThe 4% rule sets your first year's withdrawal at 4% of the portfolio and then raises that dollar amount with inflation every…
- Sharpe Ratio CalculatorSharpe ratio (1966, revised 1994)The Sharpe ratio asks how much return a portfolio earned above the risk-free rate for each unit of volatility it accepted…
- SIP (Systematic Investment Plan) CalculatorFuture value of an annuity dueA systematic investment plan is a standing instruction to buy units of a mutual fund with the same amount every month. This…
- Social Security Break-Even Age CalculatorSSA benefit reduction and delayed retirement credit rulesClaiming Social Security early gives you smaller cheques for longer; waiting gives you larger cheques for a shorter time. The…
- Social Security Claiming Age Benefit CalculatorSSA reduction and delayed retirement credit rules (42 U.S.C. §402)Social Security pays your full primary insurance amount only if you claim in the exact month you reach full retirement age…
- Solo 401(k) Contribution CalculatorIRS Publication 560; IRC §415(c), §402(g)A one-participant 401(k) lets you contribute twice — once as the employee and once as the employer — which is why…
- Step-Up SIP (Growing Contribution) CalculatorA step-up SIP raises your monthly contribution by a fixed percentage on every anniversary, so the plan grows with your income…
- Stock Average Down / Blended Cost Basis CalculatorIRS Publication 550 (cost basis)Enter up to four purchase lots and this calculator returns the share-weighted average cost of the whole position, the…
Agriculture, Livestock & Landscaping 7 calculators
- Seeding Rate per Acre CalculatorPure live seed (PLS) basis — AOSA/AOSCA seed labelling conventionsGive this calculator the stand you are aiming for and it returns the seed you actually have to buy: pounds per acre, total…
- Sod CalculatorU.S. sod trade units: square feet, slabs and palletsMeasure your lawn in sections, enter them here, and this calculator adds them up, subtracts anything you are not turfing, adds…
- Soybean Yield Estimate CalculatorYield-component method; 60 lb bushel per USDA grain standardsSoybean yield is the product of four things you can count in the field: plants per acre, pods per plant, seeds per pod and the…
- Spray Tank Mix CalculatorFIFRA — the pesticide label is the law (7 U.S.C. §136j)A boom sprayer is loaded by the tank, but labels are written by the acre. This calculator converts between them: enter your…
- Sprayer Calibration (Gallons per Acre) Calculator1/128-acre catch methodThis calculator tells you what your boom sprayer is actually putting out, in gallons per acre, rather than what the rate…
- Sprinkler Precipitation Rate CalculatorIrrigation Association precipitation-rate method (96.3 constant)Precipitation rate is how fast a sprinkler zone applies water, in inches per hour, and it is the number that turns a watering…
- Stocking Rate & Animal Unit Month (AUM) CalculatorUSDA-NRCS National Range and Pasture Handbook animal unit conventionStocking rate is a forage budget, not a rule of thumb, and this calculator builds it from both ends. Enter your herd's size…
Cloud, SaaS & IT Spend 7 calculators
- SaaS Renewal Uplift CalculatorCompound escalation of contracted priceA 7% annual uplift does not cost 7%. Over five years it compounds to 40% above today's price, and the total you pay is more…
- SaaS Seat Utilization & Shelfware CalculatorITAM software licence optimisation (ISO/IEC 19770-1)Seats bought are not seats used, and the gap is billed annually whether anyone logs in or not. This calculator turns three…
- SaaS Vendor Consolidation Savings CalculatorApplication rationalisation business caseConsolidation business cases fail on two lines that rarely make it into the slide: the migration effort, and the tools you…
- Serverless vs Container Cost CalculatorPer-invocation GB-second billing modelFunctions bill for the milliseconds you use; containers bill for the hours you reserve. That difference makes serverless…
- SLA Credit vs Actual Loss CalculatorA service credit is a discount on next month's invoice. Your loss during an outage is revenue that did not happen. This…
- Software Total Cost of Ownership CalculatorTotal cost of ownership (ISO/IEC 19770-1 asset lifecycle)The licence quote is the part of the cost that arrives as an invoice. The rest — implementation, integrations, training, the…
- Spot Instance Savings & Interruption CalculatorExponential interruption model (memoryless hazard)A 70% spot discount is not a 70% saving if the job restarts twice. This calculator prices spot capacity the way it actually…
Crafts, Textiles, 3D Printing & Photography 7 calculators
- Scrap Gold & Silver Value CalculatorTroy weight (1 troy oz = 31.1034768 g); karat marking per FTC 16 CFR Part 23This calculator separates the two numbers that get confused when you sell jewellery: the melt value , which is the market value…
- Screen Printing Ink Usage & Coverage CalculatorVolumetric ink deposit modelInk usage is a volume problem, not a mystery. The ink you lay down is the printed area multiplied by the film thickness the…
- Screen Printing Pricing CalculatorCost-plus quoting on a target gross marginThis calculator builds a screen printing quote the way a shop's books do: blanks, screen setup, ink, press time at your labour…
- Shelf Sag & Deflection CalculatorEuler–Bernoulli beam deflection; USDA Wood Handbook MOE valuesA shelf that sags is almost never a strength failure — the wood is nowhere near breaking. It is a stiffness failure, and…
- Silicone Mold Making Material CalculatorWater-displacement volume methodA block mold takes exactly as much silicone as the space around the master: the mold box's inside volume minus the volume the…
- Soap Lye & Saponification CalculatorPublished saponification values (SAP), AOCS Cd 3-25 methodEnter the oils in your recipe by weight and this calculator returns the exact mass of sodium hydroxide (for bar soap) or…
- Soap Mold Volume & Batch Size Calculator0.40 oz of oils per cubic inch ruleA soap recipe is written in oil weights, but a mold is a volume, and getting from one to the other is where most overflowed and…
Arithmetic, Algebra & Number Theory 6 calculators
- Scientific Notation CalculatorSI conventions, NIST SP 811Scientific notation writes any number as a coefficient between 1 and 10 multiplied by a power of ten, so 93,000,000 becomes 9.3…
- Significant Figures CalculatorASTM E29 significant digits practiceType a measured value exactly as it is written and this calculator tells you how many significant figures it carries, rounds it…
- Simplifying Fractions CalculatorEuclidean algorithm (Euclid, Elements VII.1–2)Enter any numerator and denominator and this calculator reduces the fraction to lowest terms, shows the greatest common divisor…
- Square Root CalculatorPrincipal square root; Newton–Raphson iterationThe square root of a number is the value that, multiplied by itself, gives that number back. This calculator returns the…
- System of 2 Linear Equations CalculatorCramer's rule for a 2×2 linear systemTwo linear equations in two unknowns describe two straight lines, and solving the system means finding where they cross. Enter…
- System of 3 Linear Equations CalculatorCramer's ruleEnter the nine coefficients and three constants of a system in the form ax + by + cz = d and this calculator solves it by…
Cooking, Baking & Brewing 6 calculators
- Sausage Seasoning & Fat Ratio CalculatorUSDA FSIS, 9 CFR 424.21 (ingoing nitrite)Professional sausage recipes are written as percentages of the meat block, never as cups and spoons, because percentages scale…
- Sourdough Levain Build CalculatorBaker's percentage (total flour = 100%)A levain build is three weights: the mature starter you seed it with, the flour you feed it, and the water. Give this…
- Sourdough Starter Hydration CalculatorBaker's percentage (total flour = 100%)Your starter is not an ingredient on its own — it is flour and water that you already mixed, days ago. Until you split it back…
- Sous Vide Cooking Time CalculatorOne-term transient-conduction solution (Baldwin sous vide heating model)Sous vide time depends on thickness, not on weight. This calculator works out how long the centre of a slab, cylinder or sphere…
- Sous Vide Pasteurization Time CalculatorD/z thermal death time model; USDA FSIS Appendix A lethality frameworkLow-temperature cooking is safe because of time, not temperature. This calculator applies the standard thermal death time model…
- Strike Water Temperature CalculatorPalmer strike-water equation (How to Brew, 4th ed.)Heat your strike water to the temperature this calculator gives you, dough in, and the mash lands on your target. The equation…
Business, Marketing & E-commerce 5 calculators
- Sales Commission CalculatorMarginal tiered plan mathEnter what you closed, your quota and your plan's rates, and this calculator returns the commission you have earned, your quota…
- Sales Funnel Drop-Off CalculatorEnter the volume at each of five funnel stages and this calculator returns the conversion rate and drop-off at every step, the…
- Sales Pipeline Coverage CalculatorExpected-value pipeline sizingEnter your quota, what you have already closed, the value of your open pipeline and your historical win rate, and this…
- Selling Price From Target Margin CalculatorTarget-margin pricing with a fee gross-upGive this calculator your landed unit cost and the gross margin you need, and it returns the price you have to charge — grossed…
- Subscription Revenue Forecast CalculatorThis calculator projects a subscription book forward one month at a time. Each month it shrinks your existing MRR by gross…
Computing, IT, Networking & Security 5 calculators
- Screen PPI / Pixel Density CalculatorISO 9241-303 display ergonomicsEnter a resolution and a screen diagonal and this calculator returns pixel density in pixels per inch, the dot pitch in…
- Server vCPU Sizing CalculatorUtilisation law (U = X × D)Capacity planning for a CPU-bound service comes down to one measurement: how many CPU-seconds a single request consumes…
- SLO Error Budget & Burn Rate CalculatorGoogle SRE error budget modelAn SLO is a promise expressed as a percentage; an error budget is the same promise expressed as a quantity of failure you are…
- Subnet Mask to CIDR Converter CalculatorRFC 4632 (CIDR), RFC 1878Routers, firewalls, cloud consoles and operating systems all describe the same 32-bit value in different notations: /26…
- System Availability Calculator (Series & Redundancy)Reliability block diagram, IEC 61078End-to-end availability is not the availability of any one component — it is what happens when you combine them. Dependencies…
Energy, Solar, Sustainability & Environment 5 calculators
- Solar LCOE CalculatorNREL / IEA levelized cost of energy definitionLevelized cost of energy converts a generation asset into a single price per kilowatt-hour: the constant revenue per kWh that…
- Solar Panel Count & Roof Area CalculatorIRC R324 / IFC 1204 access pathwaysGive this calculator a target system size and the module you intend to use, and it returns the number of modules, the total…
- Solar Panel Output (kWh) CalculatorNREL PVWatts loss modelEnter your array's DC rating, the peak sun hours your site receives, and the losses between the module glass and the meter, and…
- Solar Panel Payback Period CalculatorDiscounted cash flow analysisThis calculator returns the year your solar system finishes paying for itself, on two different definitions. Simple payback…
- Solar System Size (kW) CalculatorNREL PVWatts sizing methodEnter the kWh figure from your electric bill and this calculator returns the DC array size in kilowatts needed to hit your…
Machining, Welding & Metal Fabrication 5 calculators
- Sheet Metal Flat Pattern CalculatorK-factor developed length methodA flat pattern is the blank you cut before anything is bent. It is never the sum of the finished dimensions, because each bend…
- Spindle RPM CalculatorMachinery's Handbook cutting speed conventionCutting speed tables are published per material and tool grade, never per machine, so every job starts with the same…
- Steel Plate & Sheet Weight CalculatorThickness × area × densityPlate and sheet weight comes down to one product: thickness times area times density. The trade quotes it per square foot…
- Steel Tube & Pipe Weight CalculatorASTM A500 / ASME B36.10M section propertiesA hollow section weighs whatever the metal ring around the bore weighs, and for a round tube that reduces to a formula worth…
- Stress, Strain & Young's Modulus CalculatorHooke's law, ASTM E111 modulus determinationThree quantities describe an axially loaded bar: stress, which is force divided by cross-sectional area; strain, which is the…
Personal Finance, Loans & Credit 5 calculators
- Salary to Hourly CalculatorFair Labor Standards Act 40-hour workweek conventionDividing a salary by 2,080 hours gives you a number, but not your rate. This calculator gives you three: the standard hourly…
- Savings Account Interest CalculatorTruth in Savings Act, 12 CFR Part 1030 (Regulation DD) APY definitionThis calculator projects what a deposit account actually pays. Enter an opening balance, a monthly deposit, and either the…
- Savings Goal CalculatorFuture value of an ordinary annuityEnter what you are saving for, what you have, what you can put away each month and the account's APY, and this calculator…
- Student Loan Payment Calculator34 CFR §685.208 Direct Loan repayment plansFederal student loans default to the standard ten-year plan, but three structures are available to most borrowers and they…
- Student Loan Refinance Savings CalculatorWeighted average interest rate methodRefinancing student loans replaces several balances at several rates with one balance at one rate. Whether that saves money…
Calculus, Linear Algebra & Discrete Math 4 calculators
- Secant Method CalculatorSecant iteration and regula falsiEnter a function and two starting values and this calculator drives the secant iteration to a root of f(x) = 0 , printing every…
- Second Derivative CalculatorSecond derivative test for concavity and local extremaEnter a function and this calculator differentiates it twice, evaluates the second derivative at the point you name, scans the…
- Set Operations CalculatorNaive set theory / Boolean set algebraType two sets and this calculator returns every standard operation on them at once: union, intersection, both differences, the…
- Simpson's Rule CalculatorComposite Simpson's 1/3 and 3/8 rules with the classical fourth-derivative error boundSimpson's rule fits a parabola through every consecutive triple of points and integrates the parabolas instead of the function…
Construction, Carpentry & Concrete 4 calculators
- Section Modulus & Moment of Inertia CalculatorAWC NDS 2018 allowable stress design; NDS Supplement section propertiesThis calculator returns the two geometric properties that decide whether a beam is stiff enough and strong enough: the moment…
- Shingle Bundle & Roofing Squares CalculatorIRC 2021 Chapter 9 (Roof Assemblies)Enter the sloped area of your roof and this calculator returns the full asphalt-shingle takeoff: roofing squares including…
- Stair Rise & Run CalculatorIRC 2021 R311.7 / IBC 2021 1011Enter the total rise from finished floor to finished floor and this calculator splits it into equal risers, then returns the…
- Stair Stringer Layout CalculatorAWC DCA 6 / IRC R311.7This calculator turns a rise and a run into the numbers you actually mark on the board: the diagonal length of the cut…
HVAC, Refrigeration & Building Science 4 calculators
- SEER to EER Conversion CalculatorAHRI 210/240; DOE 10 CFR 430 Appendix M1Equipment gets quoted on four different efficiency scales and they are not interchangeable. SEER and EER measure different…
- Sensible Heat Formula CalculatorASHRAE Handbook—Fundamentals air-side sensible heat equationThis calculator solves the air-side sensible heat equation in whichever direction you need it: enter airflow and temperature…
- Subcooling CalculatorManufacturer charging data; refrigerant saturation tablesSubcooling is how far below its boiling point the liquid refrigerant has been cooled at the condenser outlet, and it is the…
- Superheat CalculatorManufacturer charging data; refrigerant saturation tablesSuperheat is how many degrees the refrigerant vapour has been heated above its boiling point after the last of the liquid has…
Physics: Mechanics, Waves & Thermodynamics 4 calculators
- Simple Pendulum Period CalculatorSmall-angle simple pendulum, T = 2π√(L/g)This calculator handles the three questions a pendulum actually raises: how long does a given pendulum take to swing, how long…
- Snell's Law Refraction CalculatorSnell's law of refraction (Snell–Descartes)Enter the refractive indices either side of an interface and the angle a ray strikes it, and this calculator returns the…
- Sound Intensity & Decibel Level CalculatorISO 1683 reference quantities (I₀ = 1 pW/m², p₀ = 20 µPa)Give this calculator any one of sound intensity, sound pressure, source power or decibel level, and it returns the other three…
- Specific Heat & Heat Energy (Q = mcΔT) CalculatorQ = mcΔTEnter a mass, a material and a temperature change, and this calculator returns the heat energy involved from Q = mcΔT , in…
Biology, Genetics & Clinical Lab 3 calculators
- Sensitivity & Specificity CalculatorWilson score interval; STARD 2015 reporting guidelineEnter the four counts of a diagnostic 2×2 table — true positives, false positives, false negatives and true negatives — and…
- Serial Dilution CalculatorISO 6887 decimal dilution practiceTell this calculator how much sample you transfer at each step, how much diluent it goes into, and how many steps you plan. It…
- Serum Osmolality & Osmolal Gap CalculatorSmithline–Gardner calculated osmolalityEnter sodium, glucose and BUN and this calculator returns the calculated serum osmolality, then subtracts it from your…
Chemistry & Chemical Engineering 3 calculators
- Solubility Product (Ksp) CalculatorIUPAC Green Book (3rd ed.) activity conventionsThis calculator converts between the solubility product K sp and molar solubility for any sparingly soluble salt A x B y , in…
- Solution Dilution Calculator (C1V1 = C2V2)Conservation of solute (C₁V₁ = C₂V₂)Enter the strength of the stock you have, the strength you want and the final volume you need, and this calculator returns the…
- Stoichiometry Calculator (Mole Ratio)Mole-ratio method from a balanced chemical equationGive this calculator a known amount of one species in a balanced equation and it converts it into any other species using the…
Education, Grading & Test Scores 3 calculators
- SAT Score Calculator (Raw to Scaled)College Board 200-800 section scaleEnter how many questions you answered correctly in each SAT section and this calculator returns a scaled score from 200 to 800…
- SAT to ACT Score Conversion Calculator2018 ACT/SAT ConcordanceThis calculator moves a score between the two American admissions tests using the concordance that ACT and the College Board…
- Speech Time CalculatorWords-per-minute delivery rateA speech has a hard time limit and a soft word count, and this calculator converts between them. Give it a script and a…
Electrical Trade & Electronics 3 calculators
- Series Resistance CalculatorKirchhoff's voltage lawResistors end to end simply add: the total resistance of a series chain is the sum of its parts. This calculator takes up to…
- Solar Panel Array Sizing CalculatorNREL PVWatts methodologyEnter what you use — a monthly bill figure works fine — along with the peak sun hours at your site, a system loss allowance and…
- Solar String Voltage CalculatorNEC 2023 (NFPA 70) Article 690.7A photovoltaic module's open-circuit voltage rises as it gets colder, and the coldest morning of the year is when a string is…
Geometry & Trigonometry 3 calculators
- Sin Cos Tan CalculatorUnit-circle definitions of the circular functions (ISO 80000-2)Type an angle in degrees or radians and read all six trigonometric functions at once: sine, cosine and tangent plus their…
- Slope of a Line CalculatorCartesian coordinate geometryEnter the coordinates of two points and this calculator returns the slope of the line through them, the rise and run it came…
- Sphere Volume CalculatorArchimedes' sphere-cylinder theoremGive this calculator any one measurement of a sphere — radius, diameter, circumference, surface area or volume — and it returns…
Insurance & Risk Management 3 calculators
- Self-Insured Retention Break-Even CalculatorLimited expected value under a lognormal severityRaising a retention always looks cheap, because the premium credit arrives immediately and the extra losses arrive later. This…
- Social Security Benefit Taxation CalculatorIRC §86 — taxation of Social Security benefits (IRS Publication 915)Whether your Social Security benefit is taxed depends on a measure the tax code calls combined income and everyone else calls…
- SR-22 High-Risk Insurance Cost CalculatorState financial responsibility filing (SR-22 / FR-44)An SR-22 is not insurance. It is a certificate your insurer files with the state confirming you carry at least the minimum…
Legal, Claims & Settlements 3 calculators
- Severance Package Evaluation CalculatorOlder Workers Benefit Protection Act, 29 U.S.C. §626(f)A severance offer is usually quoted in weeks, and weeks are the wrong unit for deciding whether to sign. What matters is what…
- Statute of Limitations Deadline CalculatorState limitation statutes; Fed. R. Civ. P. 6(a) for computing timeA limitation period is simple arithmetic wrapped around three questions that are not: when the claim accrued, whether the clock…
- Structured Settlement Present Value CalculatorIRC §104(a)(2) and §5891A structured settlement pays you over time, and the total of those payments is not what they are worth today. This calculator…
Music Theory, Audio Engineering & Instruments 3 calculators
- Song Length & Bar Count CalculatorTempo defined as quarter notes per minuteAn arrangement is built in bars and delivered in minutes and seconds, and the conversion between them decides whether a radio…
- Speaker Impedance CalculatorRated impedance per IEC 60268-5Wiring speakers together changes the load the amplifier sees, and getting it wrong is the fastest way to destroy an output…
- String Tension CalculatorMersenne-Taylor law; unit-weight form used by string manufacturersString tension is set by three things and nothing else: how heavy the string is per inch, how long the vibrating span is, and…
Plumbing, Piping & Hydraulics 3 calculators
- Septic Tank Size CalculatorEPA Onsite Wastewater Treatment Systems Manual (EPA/625/R-00/008)This calculator sizes a residential septic tank the way a health department does: estimate the design daily wastewater flow…
- Sump Pump Size & Capacity CalculatorHazen-Williams (C = 150, PVC); Crane TP-410 equivalent lengthsMeasure how fast water rises in your sump pit with the pump unplugged, and this calculator turns that into the pump duty you…
- Swimming Pool Volume CalculatorPool volume is the single number every other pool calculation depends on. Chemical doses are proportional to it, heater sizing…
Tax, Payroll & Insurance 3 calculators
- Salary to Hourly Rate CalculatorConverting a salary to an hourly rate is division, but the denominator is where offers get misjudged. This calculator uses your…
- Sales Tax CalculatorState and local sales and use tax; sourcing under Wayfair (2018)Sales tax in the United States is almost never one rate. A single purchase can carry a state rate, a county rate, a city rate…
- Self-Employment Tax CalculatorIRC §1401 self-employment tax; Schedule SE (Form 1040)Self-employment tax is Social Security and Medicare on business profit, and it catches people out because it is charged on top…
Accounting & Financial Statement Analysis 2 calculators
- Sales Volume & Sales Price Variance CalculatorFlexible-budget variance analysis (contribution-margin basis)A revenue miss is never one thing. This calculator separates it into the two effects a sales review has to argue about…
- Straight-Line Depreciation Schedule CalculatorFASB ASC 360 / IAS 16Straight-line depreciation spreads an asset's cost evenly across the years you expect to use it. Enter the capitalised cost…
Automotive, Diesel & Motorsports 2 calculators
- Speed from RPM Calculator (Gear & Tire)Rolling-circumference speed identityGive this calculator an engine speed, the transmission ratio in the gear you are in, the axle ratio and the tire diameter, and…
- Speedometer Error CalculatorUNECE R39 speedometer toleranceChange tire diameter and your speedometer starts lying, because it counts driveshaft or wheel-sensor pulses and multiplies them…
Corporate Finance & Valuation 2 calculators
- Straight-Line Depreciation CalculatorASC 360 / IAS 16 book depreciationStraight-line depreciation spreads the cost of a fixed asset evenly across the years you expect to use it. Enter what the asset…
- Sustainable Growth Rate CalculatorHiggins sustainable growth modelThe sustainable growth rate is the fastest a company can grow its sales and assets without issuing new shares and without…
Creator Economy, Streaming & Content Production 2 calculators
- Sponsorship Rate Calculator (Creator Pricing)CPM and engagement cross-check pricingThere are two defensible ways to price a sponsored integration, and quoting only one of them is how creators end up either…
- Subscriber Churn & Lifetime Value Calculator (Creators)Geometric survival model (lifetime = 1 ÷ churn)Monthly churn is the most under-read number in a creator business, because its consequences are not linear. A 5% monthly churn…
Health, Fitness & Nutrition 2 calculators
- Sleep Cycle Bedtime CalculatorAASM and SRS consensus: 7 or more hours for adultsThis calculator works backwards from the time you must be up to a bedtime that gives you a whole number of sleep cycles, and it…
- Steps to Miles CalculatorMET energy equation (ACSM) with the 2011 Compendium of Physical ActivitiesThis converts a step count into distance using a step length estimated from your height, then into calories using the MET…
Statistics & Probability 2 calculators
- Standard Deviation Calculator (Sample & Population)Descriptive statistics (Bessel-corrected sample standard deviation)This calculator returns both standard deviations from the same data: the sample value s , which divides the sum of squared…
- Survey Sample Size CalculatorCochran's sample size formulaThis calculator tells you how many completed survey responses you need to hit a target margin of error at a chosen confidence…
Time, Date, Navigation & Astronomy 2 calculators
- Schwarzschild Radius CalculatorSchwarzschild solution (1916) with CODATA 2018 constantsEnter a mass and this calculator returns the radius at which that mass would become a non-rotating black hole — its…
- Sunrise & Sunset Time CalculatorNOAA solar position algorithm (after Meeus, Astronomical Algorithms)Enter a latitude, longitude, date and UTC offset and this calculator returns sunrise, sunset, solar noon, day length and the…