Commercial Lease Calculator
Work out the real cost of a commercial lease from base rent, NNN or CAM charges, escalations and free rent, per month, per year, per square foot and over the term. Pick NNN, modified gross or gross, enter the space, the base rent, the charges and the escalation, the free months and the TI allowance, and see the year-by-year schedule, the total over the term and the effective rent per square foot, with the working shown.
Your numbers
The area the rent is charged on.
Optional: shows the load factor and cost per usable sf.
Used only when rentable sf is empty: rentable = usable × (1 + load).
The landlord's current estimate.
Your estimate: charges follow actual costs.
3 means 3% (or $3.00 per sf on the fixed option).
At the start of the term.
Optional. The landlord's tenant improvement allowance.
Total occupancy cost over the term
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- Average a month
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- Effective rent per sf a year
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- Effective rent per sf a month
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- Effective cost a month (after TI)
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- Net effective base rent per sf a year
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- First year, a month (after free rent)
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- Base rent over the term
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- NNN charges over the term
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- Rentable area
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An estimate from the numbers you typed. Not legal or financial advice: the lease wording decides what is charged, and NNN and CAM charges follow the landlord's actual costs.
Charges are an estimate: NNN and CAM are reconciled to actual costs each year, and many leases cap only the controllable ones.
The calculation runs in your browser and ParrotNotes does not store your numbers. They sit in the page address so you can bookmark or share the result.
How the lease cost is worked out
Each lease year starts from the base rent rate. Year one is the quoted rate; each year after it rises by the escalation, either a percent (3% a year compounds: $24.00, $24.72, $25.46) or a fixed amount per square foot ($0.50 a year: $24.00, $24.50, $25.00). Rate × rentable square feet × months ÷ 12 is the base rent for the year, less any free months. NNN or other charges are added the same way, with an optional yearly increase since they follow actual costs.
Worked example: 2,500 rentable sf at $24.00 a sf NNN, $8.00 of NNN charges, 3% a year, 60 months with 3 months of free base rent and a $10.00 TI allowance. Year one is $45,000 of base rent and $20,000 of charges, $65,000; year five is $67,530.53 + $20,000. Over the term the tenant pays $403,548.15: $303,548.15 of base rent and $100,000 of charges. Less the $25,000 TI allowance that is $30.28 a sf a year effective, $2.52 a sf a month; net effective base rent is $22.28.
Gross, modified gross and NNN
Gross: one rate, and the landlord pays the operating costs out of it; the calculator adds no charges. Modified gross: the lease names the costs the tenant pays on top (often utilities, janitorial or increases over a base year); type those as the charges. NNN: the tenant pays base rent plus its share of taxes, insurance and CAM. You can enter NNN as one figure or as CAM, taxes and insurance separately. Gross and NNN rates are not comparable until the charges are added, which is what the total per sf column does.
Percentage rent for retail leases
Some retail leases add a percentage of sales above a breakpoint. With a natural breakpoint, the breakpoint is the annual base rent divided by the percentage rate: $60,000 of base rent at 6% breaks at $1,000,000 of sales, and $1,200,000 of sales adds 6% × $200,000 = $12,000. A fixed (artificial) breakpoint is a dollar figure the lease names. The calculator keeps sales flat across the term and prorates a partial year; the lease's definition of gross sales decides what counts.
For tenant reps and leasing brokers
Two proposals rarely line up: one is gross with two free months, the other NNN with a bigger TI allowance and a fixed bump. Run each through the calculator with the same area and term and compare the total over the term and the effective rent per square foot. Note what is still open, such as the CAM estimate, the load factor or a cap on controllable charges, and bring it to the next call.
Sources for the definitions, read on 2026-10-31. Lease terms differ by market and by lease; the signed lease governs:
- BOMA International, BOMA Standards (BOMA 2024 for Office Buildings, ANSI/BOMA Z65.1-2024)
- Extreme Measures, BOMA office standard overview: usable and rentable area as defined in BOMA 1980 and 1996
- Open Exam Prep, CCIM study guide 9.3: gross, modified gross, single, double and triple net leases
- Open Exam Prep, CCIM study guide 10.3: effective rent, free rent (gross and net) and TI allowances
- Altus Group, Using percentage rent in a commercial real estate lease (natural breakpoint)
This page prices the lease for the tenant. To compare asking rents across listings, use the price per square foot calculator; to value the building from the landlord's side, the cap rate calculator; and to compare leasing and buying the equipment or vehicles for the new space, the lease vs buy calculator.
More for commercial real estate brokers: How commercial real estate brokers document tours and client calls, How to run a client meeting.
The terms get agreed out loud first
The rent, the free months, the TI and who pays for what are talked through on the tour and the negotiation calls before anyone writes them down. Record the call in ParrotNotes and the summary lists the terms discussed, so the numbers here and the letter of intent match the conversation.
Get Started FreeRelated tools
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- Cap Rate CalculatorWork out a property's cap rate from net operating income and price, the value at a target cap rate, cash on cash return and price per square foot.Open the tool
- Lease vs Buy CalculatorCompare the total cost of leasing and buying a car or piece of equipment over the same period, including the value left at the end.Open the tool