How this instrument works
A commercial lease rarely prices space with one number. Landlords quote a base rent per square foot per year, then bill property tax, building insurance, and common-area maintenance (CAM) — landscaping, parking-lot upkeep, shared utilities, property management — separately, also per square foot per year. Add the two rates, multiply by the square footage, and you have the annual cost of the space; that structure is called a triple net, or NNN, lease, and it is the default for most retail, office, and industrial space in the United States.
Retail tenants sizing a storefront, small-business owners budgeting occupancy costs before signing, and commercial brokers doing quick math during a property tour all reach for this arithmetic before the paperwork does. The formula is deliberately shaped as base plus NNN, not one blended figure, because the NNN portion is an estimate the landlord sets each year from actual operating costs — it can rise even when the base rent is locked for the whole term.
The number this returns is the occupancy cost only. It excludes percentage rent that some retail leases add once a tenant's sales cross a threshold, the annual escalations (fixed percentage bumps) common in multi-year terms, and any free-rent or tenant-improvement allowance negotiated at signing. Those adjust the true price of the space up or down and belong in a separate line-by-line comparison, not folded into this single-year figure.
- Enter your square footage in Leased space, sq ft — use the figure the lease document bases charges on.
- Enter the landlord's quoted rate in Base rent, $/sqft/year.
- Enter NNN charges (taxes+insurance+CAM), $/sqft/year — ask the broker for this if the listing only shows the base rate.
- Read Total annual rent — the combined rate times your square footage.
- Read Monthly rent — the annual figure divided by twelve, the amount that actually clears your account each month.
Worked example — a 2,000 sq ft retail space
A tenant sizing a 2,000 sq ft retail space finds a base rent of $25 per square foot per year, with NNN charges — property tax, insurance, and common-area maintenance — billed separately at $8 per square foot per year. Combined that is $33 per square foot; multiplied by the 2,000 sq ft footprint, the instrument returns $66,000 a year.
Divide by twelve and the invoice due each month is $5,500 — not the $50,000-a-year, $4,166-a-month figure a shopper gets by pricing only the base rent. That $16,000 annual gap between the two numbers is exactly why lease comparisons that quote the base rate alone routinely understate the real cost of occupying the space.
Questions
What exactly do NNN charges cover?
NNN — the three 'nets' — are property tax, building insurance, and common-area maintenance: landscaping, parking-lot repair, shared utilities, and property management. A landlord estimates these per square foot for the year and bills them alongside base rent; most leases reconcile the estimate against actual costs annually, so the rate can shift year to year even when the base rate does not.
Why do two lease quotes with different numbers cost the same?
A landlord quoting $33/sqft full-service and one quoting $25/sqft base plus $8/sqft NNN separately are describing the identical $66,000 lease on a 2,000 sq ft space — the sum matters, not which line item carries which label. Ask whether a quoted rate is base-only or already includes taxes, insurance, and CAM before comparing two properties.
Does this include rent escalations or free-rent periods?
No. Many multi-year commercial leases step the rate up a fixed percentage each year, or grant a month or two of abatement as a signing concession. This instrument prices one year at one rate; approximate a multi-year lease by re-running it with each year's escalated base rent and comparing the totals.
Is CAM structured the same way on every lease?
No. CAM terms vary by property and by negotiation. Some leases cap annual CAM increases at a fixed percentage, some exclude capital repairs from the tenant's share, and some pass through a management fee the tenant never sees itemized. Read the CAM clause and any expense cap before treating a broker's quoted NNN rate as fixed.
How is this different from pricing an apartment?
Residential rent is usually one flat monthly figure with taxes and insurance already covered by the landlord. Commercial NNN leases separate the two deliberately, quote per square foot per year rather than per month, and shift property tax, insurance, and maintenance costs onto the tenant — which is why this instrument needs three inputs instead of one.
Should I enter usable or rentable square footage?
Use whichever figure the lease document prices rent against, not the marketing flyer. Rentable square footage typically adds a share of common areas — lobbies, hallways, shared corridors — on top of usable square footage, and landlords sometimes quote rent per rentable square foot even though the tenant occupies only the smaller usable space.
References
- U.S. Small Business Administration — Buy or lease business real estate
- IRS Publication 535 — Business Expenses, including rent
Read this first: This instrument shows arithmetic, not advice. Real offers add fees, taxes and terms that vary by lender and place — verify the figures against your actual paperwork before deciding anything.