Laundry Load Cost Calculator

What a load of laundry actually costs

Five things go into a load, and their sizes are nothing like what most people assume. The washing machine's own electricity — motor, pump, controls — is trivial: a modern front-loader uses about 0.15 kWh per cycle, roughly two and a half cents. The water is a few cents more. The three that matter are heating the water, running the dryer, and detergent.

Heating dominates the wash. Raising 7.5 gallons of water by 65 °F takes about 4,066 Btu, which after heater losses is around 1.32 kWh — nearly nine times the washer's own electricity. That single fact is why "wash cold" is the standard advice: it removes the largest part of the wash cost outright, and it removes it whether your water heater is cheap or expensive to run.

Drying is larger still. A vented electric dryer uses 2.5 to 4 kWh per load because it must evaporate the water the spin cycle left behind, and evaporation is expensive: it takes roughly 970 Btu to boil off a single pound of water. At typical US electricity rates the dryer alone commonly costs more than everything else in the cycle combined.

Detergent is not negligible either. At $0.35 a load it can exceed the water and the washer's electricity together, which makes dosing correctly a cost decision as well as a laundry one.

This calculator prices each of the five separately, so you can see which one to attack.

The formula, term by term

Four terms are simple products: washer kWh times the electricity rate, gallons times the water-and-sewer rate, dryer kWh times the electricity rate, and supplies as a flat amount. The fifth, water heating, is the only piece of physics here.

The heat. Use the sensible heat equation Q = m·c·ΔT. Water's specific heat is 1 Btu per pound per degree Fahrenheit, which makes the arithmetic unusually clean: the Btu required is simply pounds of water times the temperature rise. One US gallon of water weighs 8.34 pounds, so Q = gallons × 8.34 × ΔT.

The temperature rise. This is your hot water setting minus your incoming cold supply, not the absolute temperature. A 120 °F tank on a 55 °F winter supply is a 65 °F rise; in summer the same tank on a 70 °F supply is only a 50 °F rise, so your laundry genuinely costs less in August. Enter the rise directly, in Fahrenheit degrees or Celsius degrees — a Celsius degree is 1.8 times a Fahrenheit degree, and for a difference that conversion is a clean multiplication with no offset.

The heated share. A cold wash heats nothing. A warm wash on most machines is roughly half hot; a hot wash is all of it. Rinse water is cold on nearly every modern machine regardless of wash setting, which is why even a hot wash heats less than the full fill volume — set the share from what your machine actually does, not from the dial label.

Efficiency. Divide the heat required by the heater's efficiency to get the fuel actually consumed. Electric resistance is 95–98% because essentially all the energy ends up in the water; an older gas tank is 60–70% because a large fraction goes up the flue. A heat-pump water heater exceeds 100% — typically 200–400% — because it moves heat from the room rather than generating it, and that is a legitimate entry here rather than an error.

Then convert. 3,412.14 Btu per kWh for electricity, 100,000 Btu per therm for gas.

How to read the result

Look at the breakdown chart before the total. The component ranking tells you what to change, and it varies a lot by household. A home with a gas water heater and an electric dryer will find the dryer dwarfs everything; a home with an electric tank washing hot will find heating comparable; a home line drying already has nothing left to cut but detergent and water.

Compare the per-load figure against a laundromat. Coin machines in the US typically run a few dollars for a wash and a similar amount for a dry, so a home cost of around $1.29 is a fraction of it — but the comparison is only fair if you also account for the machines themselves. A $1,600 washer-and-dryer pair over ten years at 260 loads a year adds about $0.62 per load in capital, plus repairs, which changes the answer for a low-volume household considerably.

Treat the cold-wash saving as available with almost no downside on modern detergents, which are formulated with enzymes that work at ambient temperature. The classic exceptions are genuine sanitation needs — illness in the house, cloth nappies, heavily soiled work clothing — where hot water is doing a job that detergent cannot.

The line-drying saving is the biggest single number on the page for most households, and it is also the one with a real cost in time and space. Half measures work: hanging shirts and finishing towels in the dryer captures a good share of the saving with much less disruption than committing to everything.

Cost to heat wash water, per load

Each row is gallons × 8.34 × 65 Btu, divided by the efficiency, then converted at 3,412.14 Btu/kWh or 100,000 Btu/therm and priced. Gas heating costs roughly 40% of electric resistance heating at these rates, which is why the fuel selector matters more than the efficiency setting.

What this calculation assumes

• It assumes an electric dryer. A gas dryer uses roughly 0.2 kWh of electricity plus about 0.2 therms of gas per load. Price that separately and enter the equivalent kWh if you want the dryer line to be right.
• It prices marginal energy, not average. On a tiered or time-of-use tariff, laundry run in a peak window costs more than your average rate. Use the rate for the block you are actually in.
• It ignores standby losses. A water heater loses heat to the room continuously whether you do laundry or not, so that loss is not a cost of washing and is excluded here.
• It assumes the machine finishes in one cycle. Re-running a load because it did not dry doubles the largest line on the page.
• It excludes the machines themselves. Purchase price, delivery, installation and repair are capital costs. Divide them over your expected loads separately when comparing against a laundromat.
• It uses a single detergent figure. Pods, liquid and powder differ substantially per load, and overdosing is common. Divide the container price by the dose count the label actually claims.

Where laundry sits in the household bill

Laundry is usually the third-largest indoor water use after toilets and showers, and a meaningful slice of the electricity bill because of the dryer. Working through household costs in order of size, the toilet is often the largest single water item — the toilet flush water usage calculator quantifies that and prices a fixture swap — while the dryer is one of the largest single electrical items, alongside water heating itself.

For any other appliance, the same method applies with only the energy term: the appliance energy cost calculator takes wattage and runtime and returns a running cost, which is the right tool for a dehumidifier, a space heater or an old refrigerator. Where the laundry bill is shared with housemates, the roommate utility bill split calculator handles the allocation, and person-days is the right method because laundry scales with people rather than with rooms.

If you are comparing home laundry against a laundromat or a building's shared machines, remember to include capital. A washer and dryer pair amortised over ten years adds roughly sixty cents per load for a household running five loads a week, and considerably more for a household running two. That is often the deciding term for a one-person apartment, and it is the reason the arithmetic that obviously favours home laundry for a family does not automatically favour it for a single occupant.