Estimate your total monthly and annual cost for a commercial space under a triple net (NNN), modified gross, or gross lease.
Enter the number exactly as quoted. Choose the matching period so a monthly quote is not treated as a yearly one.
Used for NNN and modified gross. Ignored for a full-service gross lease.
This tool turns a per-square-foot rent quote into a monthly budget, an annual budget, and an all-in rate you can compare with other quotes. You enter the size of the space, the base rent exactly as quoted, whether that quote is per year or per month, and the lease structure. For a net (NNN) or modified gross lease you also enter the operating expenses you would pay on top of base rent, such as common area maintenance (CAM), property taxes, and building insurance. You can add other monthly costs that sit outside the rent, a yearly rent increase, and a lease term in years.
The math is deliberately simple so that you can check it by hand. The tool converts the quote to dollars per square foot per year, adds the operating expenses when the lease structure calls for it, multiplies by the square footage, and divides by 12 for a monthly figure. It then adds your other monthly costs, and, for the term total, raises only the base rent by your chosen yearly percentage while holding expenses and other costs flat. Everything runs in your browser; nothing you type is sent anywhere. The full formula is on the methodology page.
The calculator does not know your lease, your landlord, or your local market. It is a way to sanity-check a quote you already have, or to budget roughly before you start touring spaces. It is not a substitute for reading the lease.
Commercial listings can measure space in two ways. Rentable square feet are your suite plus a share of shared areas such as lobbies, corridors, and common restrooms. Usable square feet are the space inside your own walls. Quoted rates are very often per rentable square foot. If a listing gives you a usable figure but prices per rentable foot (or the other way round), the cost per foot you actually experience will differ from the headline. Ask which figure the quote uses, and read our guide on rentable vs. usable square feet.
Base rent is the core rent before operating expenses. Many listings quote it in dollars per square foot per year, but some quote dollars per square foot per month. The two are easy to confuse, and mixing them up changes the answer by a factor of 12. That is why this calculator has a separate "rent is quoted per" selector: type the number exactly as you were given it, then choose year or month. A quote of $2.00 per square foot per month is the same as $24.00 per square foot per year.
Choose Net lease (NNN) when the tenant pays base rent plus a share of property taxes, insurance, and common area maintenance. Choose Gross (full service) when the quoted rent is one all-inclusive amount and the landlord pays those operating costs. Choose Modified gross when the lease sits somewhere in between. There is no single standard for modified gross, so the amount you pay on top of rent depends entirely on the lease. For modified gross the calculator adds whatever operating-expense figure you type in. See NNN vs. gross lease explained for the details.
For NNN and modified gross leases, enter your estimated share of CAM, taxes, and insurance per square foot, using the same period (year or month) as the rent. Landlords usually give an estimate on a listing sheet or letter of intent and later compare it with actual costs in a yearly reconciliation. Because the estimate can move, ask for an itemized breakdown. Our article on CAM charges and reconciliation shows how a true-up bill happens. For a gross lease this field is ignored.
Utilities that you pay separately, janitorial service for your own suite, parking, and similar items can be entered as a flat dollar amount per month. They are added to the result and held flat over the term.
Many multi-year leases raise base rent on a schedule, either a fixed percentage or a rate linked to an index. Enter the percentage from your lease or proposal and the number of years. The term total applies that increase to base rent only. If your lease also lets operating expenses rise, the true total will be higher than shown.
A business is looking at a 2,500-square-foot suite quoted at $24.00 per square foot per year, NNN, with estimated CAM, taxes, and insurance of $7.50 per square foot per year. The all-in rate is $24.00 + $7.50 = $31.50 per square foot per year. Multiply by 2,500 square feet: $78,750 per year, or about $6,563 per month ($6,562.50 before rounding). With a 3% yearly increase on base rent over five years, base rent is $60,000 in year 1 and rises each year: the five years of base rent add up to about $318,548. Expenses held flat are $18,750 a year, or $93,750 over five years, so the term total is about $412,298. These are the default values in the calculator above.
Now suppose another landlord quotes the same 2,500 square feet at $34.00 per square foot per year, full service gross. That is $85,000 per year, about $7,083 per month. Year 1 is $6,250 more than the NNN quote ($85,000 minus $78,750). Over five years with a 3% yearly increase applied to the whole rent, the gross quote comes to about $451,277, compared with $412,298 for the NNN quote. The NNN quote looks cheaper in this example because we held expenses flat and charged only base rent with an increase. In real life a gross lease may include an expense stop or base year that passes later increases to you, and NNN expenses can rise, so you should ask for both the rent schedule and the expense history before deciding. These numbers are for illustration only and are not market rates.
A 1,800-square-foot space is quoted at $2.00 per square foot per month. If you typed 2 into a yearly field you would get $3,600 a year, which is off by a factor of 12. Selecting "per month" converts it correctly: $2.00 × 12 = $24.00 per square foot per year, $43,200 a year, or $3,600 a month.
The calculator does not model free-rent or abatement periods, tenant improvement allowances, percentage rent, security deposits, taxes on your business, rent escalations on expenses, or the specific exclusions and caps in your lease. It does not provide market rents; the figures in the form and in the examples are placeholders you should replace with your own quote. It also does not tell you whether a lease is fair or enforceable. Lease terms differ by property, landlord, and state, and nothing on this site is legal advice. For a lease that matters, have a commercial real estate attorney review the document, and consider a tenant-representation broker.