What triple net means and what the three nets are
In a triple net lease the tenant pays base rent plus three categories of building cost that a residential tenant never sees: real estate taxes, building insurance, and common area maintenance. That is where the name comes from — three items net of base rent. The landlord is left holding, in principle, only the structure and the capital.
All four figures are quoted per rentable square foot per year in the American market, which is why a lease reads "$24.00 NNN, estimated nets $8.60" rather than in dollars per month. To get a monthly cheque you add the rates, multiply by the rentable area, and divide by twelve. On 3,500 square feet at $24.00 base and $8.60 of nets, that is $32.60 × 3,500 ÷ 12 = $9,508.33.
The nets are reimbursements at cost, not profit centres, and that distinction shapes how they behave. The landlord bills a monthly estimate through the year, then reconciles after year end against what was actually spent and invoices or credits the difference. Your budget should therefore treat the net charges as a forecast with a true-up, and the lease should give you the right to review the reconciliation statement.
Triple net is one point on a spectrum. A full-service or gross lease bundles everything into one rate. A modified gross lease has the landlord pay operating costs in a base year and the tenant pay increases above it. A single or double net lease passes through taxes only, or taxes and insurance. Comparing quotes across these structures is exactly what the all-in rate is for.
Rentable area is not the area you occupy
The square footage in your lease is rentable area, and it is larger than the space you can put desks in. Rentable area is your usable area plus a proportionate share of the building's common areas — lobbies, corridors, shared restrooms, mechanical rooms. The ratio between them is the load factor, and 12% to 20% is a common range in multi-tenant office buildings.
The consequence is direct: rent is charged on rentable feet, so a 3,000-square-foot usable suite in a building with a 16% load factor is leased as 3,480 rentable feet, and every rate on this page is multiplied by the larger number. A quote that appears cheaper per foot can be more expensive per usable foot if the load factor is higher, which is why two offers should be compared on rent per usable square foot as well as per rentable foot. The load factor calculator does that conversion.
Measurement is not arbitrary. The Building Owners and Managers Association publishes the standards most American office and retail leases reference, and the standard a lease cites determines what counts as rentable. Ask which BOMA standard and which year the measurement follows, and ask for the measurement certificate. On a 3,500-foot suite at $32.60 all-in, a 5% measurement difference is $5,705 a year.
Worked example: 3,500 SF at $24.00 NNN with $8.60 of nets
You are quoted a 3,500 rentable square foot suite at $24.00 per foot base rent, triple net. The landlord's estimate for the coming year is $3.50 per foot of property tax, $0.85 of insurance and $4.25 of CAM. Base rent steps 3% each year, you expect the nets to grow about 3% as well, and the term is five years.
- Net charges per foot. $3.50 + $0.85 + $4.25 = $8.60/SF/yr.
- All-in rate. $24.00 + $8.60 = $32.60/SF/yr.
- First-year annual rent. $32.60 × 3,500 = $114,100.
- First-year monthly rent. $114,100 ÷ 12 = $9,508.33.
- Monthly net charges alone. $8.60 × 3,500 ÷ 12 = $2,508.33.
- Nets as a share of the total. $8.60 ÷ $32.60 = 26.38%.
Now the term. Because base and nets both escalate at 3%, the whole $114,100 grows at 3% a year, so the five-year total is a geometric series: $114,100 × (1.03⁵ − 1) ÷ 0.03 = $114,100 × 5.3091358 = $605,772.40.
- Average annual rate over the term. $605,772.40 ÷ (3,500 × 5) = $605,772.40 ÷ 17,500 = $34.6156/SF/yr.
That average is the number to quote when someone asks what the space costs. The headline was $24.00; the space actually costs $34.62 per rentable foot per year averaged across the term, or 44.2% more than the number on the flyer — 34.6156 ÷ 24.00 − 1 = 0.442.
Reading the result, and comparing NNN against gross
The all-in rate is the only figure that compares across lease structures. A $32.00 full-service quote and a $24.00 triple net quote with $8.60 of nets are not close: the second is $32.60 in year one and rising, and the tenant carries the risk of every tax reassessment and every parking-lot repaving. Convert both to all-in dollars per rentable foot before forming a view.
Net charges as a share of the total is a useful sanity check on the quote. On the worked example the nets are 26.4% of the all-in rate. A much higher share invites questions: is the building carrying an unusual tax burden, is management fee inside CAM and at what percentage, are capital replacements being amortised into CAM rather than borne by the landlord, and is there a cap on controllable expenses?
Escalation is where a long lease is won or lost. Base rent escalation is contractual and negotiable — a fixed percentage step, a CPI adjustment, or a mid-term market reset. Net charge growth is not contractual at all; it follows what the landlord actually spends, so the only protection available is a cap. The common structure caps controllable CAM at a few percent a year while leaving taxes, insurance, snow removal and utilities uncapped, on the argument that the landlord does not control them.
The term total tells you what you are committing to. $605,772 over five years is a corporate obligation of that size, usually personally guaranteed for a small tenant. It is worth seeing the number before the discussion turns to which suite has better light.
Monthly rent by size and all-in rate
| Rentable area | $25/SF/yr | $30/SF/yr | $35/SF/yr | $40/SF/yr |
|---|---|---|---|---|
| 1,000 SF | $2,083.33 | $2,500.00 | $2,916.67 | $3,333.33 |
| 2,500 SF | $5,208.33 | $6,250.00 | $7,291.67 | $8,333.33 |
| 5,000 SF | $10,416.67 | $12,500.00 | $14,583.33 | $16,666.67 |
| 10,000 SF | $20,833.33 | $25,000.00 | $29,166.67 | $33,333.33 |
These are all-in figures, so they already include the three nets. Each $1 per foot of annual rate is worth SF ÷ 12 in monthly rent — about $83.33 a month on 1,000 feet and $833.33 on 10,000.
Ask what is inside CAM before you sign
CAM is the least standardised of the three nets and the one that generates the most disputes. Before signing, get the lease to answer these in writing: is a management fee charged inside CAM and at what percentage of what base; are capital expenditures excluded, or amortised over their useful life and passed through; is there an administrative markup on top of actual cost; is there a cap on controllable expenses and what is excluded from it; are you entitled to audit the reconciliation, within what window, and who pays if an error above a threshold is found.
Also confirm the pro-rata share formula. Your share should be your rentable area divided by the building's total rentable area, and it should be clear whether the denominator is the building's total area or its occupied area — the second shifts the cost of vacancy onto the tenants who are there.
What this calculator does not include
- Utilities metered to your suite. Electricity, gas and sometimes water are usually billed directly to the tenant and sit outside the three nets entirely.
- Free rent and tenant improvement allowances. Both materially change the economics of a deal. Use the net effective rent calculator to fold them into a single comparable rate.
- Percentage rent. Retail leases often add a share of sales above a breakpoint on top of base rent.
- Your own insurance, janitorial and interior maintenance. On a true triple net the tenant carries these directly for the demised premises.
- The annual reconciliation. Net charges are estimates billed monthly and trued up after year end; the settlement can be a bill or a credit.
- Security deposit, letter of credit and guarantee. Cash requirements at signing that no rate per foot reveals.
- Sales tax on rent, which some jurisdictions levy on commercial leases.
Lease terms worth knowing
- Load factor
- Rentable area divided by usable area. A 16% load factor means you are billed for 1.16 square feet for every square foot you can occupy.
- Base year
- In a modified gross lease, the year whose operating costs the landlord absorbs. The tenant pays only the increase above that base.
- Controllable expenses
- CAM items a landlord can influence — landscaping, cleaning, management — as opposed to taxes, insurance and utilities. Expense caps usually apply only to these.
- Reconciliation
- The annual true-up comparing estimated net charges billed against actual costs incurred, producing a bill or a credit.
- Absolute net
- A lease in which the tenant carries even structural and roof obligations. Common on single-tenant net-leased buildings and stricter than ordinary triple net.
Where the NNN rate fits in the wider deal
For a tenant, the all-in rate is only step one. Convert competing offers to net effective rent with the net effective rent calculator, which absorbs free rent months and improvement allowances into a single average rate, and normalise the areas with the load factor calculator so you are comparing usable space rather than measurement conventions. Retail tenants should also model the overage with the percentage rent breakpoint calculator, since sales above the breakpoint add rent that no per-foot rate shows.
For an owner, the triple net structure is what makes commercial property behave like a bond: the reimbursements shift operating cost risk to the tenant, so net operating income is more predictable than in a gross-leased building. That predictability is priced. Feed the rent roll into the net operating income calculator and then the cap rate calculator, and remember that credit quality and remaining term drive value at least as much as the rate per foot — a fifteen-year lease to an investment-grade tenant trades at a materially lower cap rate than the same building leased short to an unrated one.
Nothing on this page is legal advice, and lease drafting varies enormously between markets and property types. Have a tenant representative or a real estate attorney read the operating expense clause before you sign; it is the clause that produces the surprises.