Every commercial mortgage decision runs through one ratio. Before a lender cares about your credit score, your track record, or your story, it divides the property's income by the proposed loan payment and reads the result: can the building pay for the debt? That number — the debt service coverage ratio, or DSCR — decides whether the deal is bankable and, just as often, how large the loan can be.
The formula is one line. The fight is over the inputs: what counts as income, which payment gets used, and whose assumptions win. This guide works through all of it on a full numeric example — and then shows the calculation lenders actually run, which is the same formula backward.
How is DSCR calculated for a commercial property loan?
DSCR for a commercial property loan is calculated by dividing the property's annual net operating income by its annual debt service — all principal and interest owed on the loan for the year. A property producing $280,800 of NOI against $233,495 of annual loan payments carries a DSCR of 1.20x: income covers the debt 1.2 times over.
The formula:
DSCR = Net Operating Income ÷ Annual Debt Service
Both inputs are annual figures for the same property and the same proposed loan. A DSCR of exactly 1.00x means the building earns precisely its debt payment — one bad month from a shortfall — which is why lenders demand a cushion above 1.00x, most commonly 1.20x to 1.25x on stabilized commercial property. What trips up borrowers is never the division; it is that the lender's NOI and the lender's debt service are computed by rules, not taken from your spreadsheet. Those rules are the next two sections.
What counts as net operating income in a DSCR calculation?
Net operating income is effective gross income — scheduled rents plus other income, minus vacancy and credit loss — less all operating expenses: property taxes, insurance, management, repairs, utilities, and administrative costs. It excludes debt service itself, depreciation, income taxes, and capital expenditures. Lenders recalculate NOI to their own underwriting rules rather than accepting the owner's figure.
Three adjustments show up in nearly every underwritten NOI, and each one moves the ratio:
- A vacancy floor. Even a fully occupied building gets underwritten at a minimum vacancy factor — commonly 5%, higher in soft submarkets — because the lender is sizing a multi-year loan, not a snapshot.
- An imputed management fee. Self-managing owners often leave management out of expenses; underwriters add one back, typically 3-5% of effective gross income, because the lender must assume it may someday operate the building with paid management.
- Replacement reserves. Many lenders — agency lenders as a rule — deduct an annual capital reserve (for multifamily, commonly around $250 per unit) before computing the ratio, so their underwritten NOI sits below the accounting NOI.
The methodology question worth asking every lender upfront: trailing-12 actuals, or pro forma? A stabilized deal is underwritten on trailing actuals; a value-add story may get partial credit for projected rents, usually haircut for conservatism. The same building can clear one lender's DSCR test and miss another's without a single number on the rent roll changing.
What counts as debt service — and does interest-only change the ratio?
Debt service is the annual principal and interest on the proposed loan — taxes and insurance are already inside NOI as operating expenses, so they are not counted again. An interest-only period raises the in-place ratio because payments drop to interest alone, but many lenders, agencies included, underwrite to the fully amortizing payment regardless.
The numbers make the point. A $3,000,000 loan at 6.75% on a 30-year amortization costs $19,458 a month — $233,495 a year. The same loan interest-only costs 6.75% of $3,000,000, or $202,500 a year. Against $280,800 of NOI, that is the difference between a 1.20x and a 1.39x DSCR ($280,800 ÷ $202,500 = 1.39) — same building, same loan amount, same rate.
This is why the underwriting convention matters more than the payment schedule. A lender that underwrites the amortizing payment is protecting itself against the day the IO period ends; a lender that underwrites the IO payment is giving your deal credit for near-term cash flow. Neither is wrong, but they produce different maximum loans on identical deals — one of several reasons quotes on the same property can differ far more than the rates printed on them.
What does a full worked DSCR example look like?
Take a 20-unit apartment building renting at $2,000 per unit per month, financed with a $3,000,000 loan at 6.75% over 30 years. Working from scheduled rents down to NOI and dividing by the annual payment produces a DSCR of 1.20x — the arithmetic below shows every step.
| Line item | Amount |
|---|---|
| Gross scheduled rents (20 units × $2,000 × 12) | $480,000 |
| Other income (laundry, parking, fees) | +$12,000 |
| Vacancy and credit loss (5% of scheduled rents) | -$24,000 |
| Effective gross income | $468,000 |
| Operating expenses (taxes, insurance, management, repairs, utilities — 40% of EGI) | -$187,200 |
| Net operating income | $280,800 |
Now the debt side. A $3,000,000 loan at 6.75% fixed on a 30-year amortization pays $19,458 per month, or $233,495 per year.
DSCR = $280,800 ÷ $233,495 = 1.20x
The building earns $1.20 for every $1.00 of debt payment — a ratio most stabilized-property lenders will accept. Run your own property through the free underwriting calculator, and use the amortization schedule to see how the payment splits between principal and interest over the term.
How do lenders use DSCR to size a commercial loan?
Lenders run the formula backward: divide underwritten NOI by the required DSCR to get the maximum annual debt service the property supports, then divide that by the loan constant to get maximum proceeds. On $280,800 of NOI at a required 1.25x, the ceiling is $224,640 of debt service — about $2.89 million of loan.
Step by step on the example deal, against a lender requiring 1.25x coverage:
- Maximum debt service: $280,800 ÷ 1.25 = $224,640 per year.
- Loan constant: at 6.75% and 30-year amortization, a loan pays about 7.78% of its balance per year in principal and interest — an annual constant of 0.0778.
- Maximum proceeds: $224,640 ÷ 0.0778 ≈ $2.89 million.
So even though the borrower asked for $3,000,000 — and even if the LTV math supports it — this lender's proceeds top out around $2.89 million. That is a DSCR-constrained deal: the coverage test, not the appraisal, sets the loan. In higher-rate environments most deals are DSCR-constrained, because rate feeds directly into the constant.
Rate sensitivity is worth seeing once. Move the same 30-year loan from 6.75% to 7.00% and annual debt service on $3,000,000 rises from $233,495 to $239,509 — the DSCR falls from 1.20x to 1.17x with no change to the building whatsoever. That is why proceeds quotes drift with the market between term sheet and close, and why where SOFR and Treasury yields sit on your closing date matters as much as the spread you negotiated. Current levels are on the rate dashboard.
The practical consequence: getting maximum proceeds is a shopping problem. Required DSCRs, vacancy floors, reserve deductions, and IO underwriting conventions all differ by shop, so the same NOI supports different loan amounts at different lenders — sometimes by hundreds of thousands of dollars. YieldStack — a commercial mortgage broker and marketplace, not a lender — runs this math before your deal goes out: a human deal team pre-screens the package for bankability and computes the DSCR the way credit teams will, and the platform matches the deal against 5,000+ loan programs whose coverage rules the property actually clears.
Submit your deal and see what your NOI actually supports →
How is commercial DSCR different from DSCR on a 1-4 unit rental loan?
They divide different things. Residential DSCR programs on 1-4 unit rentals divide monthly gross rent by the full monthly housing payment — principal, interest, taxes, insurance, and association dues (PITIA) — with no deduction for operating expenses. Commercial DSCR divides NOI, which is income after all expenses, by principal and interest alone.
| 1-4 unit DSCR program | Commercial property loan | |
|---|---|---|
| Income side | Monthly gross rent (appraiser's market-rent schedule or the lease) | Annual NOI after vacancy and all operating expenses |
| Payment side | Full PITIA — principal, interest, taxes, insurance, HOA dues | Annual principal and interest only |
| Operating expenses | Not deducted (taxes and insurance sit in the payment instead) | Deducted from income before dividing |
| Typical minimum | 1.00x-1.20x | 1.20x-1.25x |
The consequence: the two ratios are not comparable numbers. A 1.20x on a commercial loan means the property clears its debt by 20% after paying every operating bill; a 1.20x on a rental-home program means rent exceeds the housing payment by 20% before repairs, vacancy, or management. Marketing pages and even loan officers blur the two constantly — a confusion our guide to what investors get right and wrong about DSCR loans untangles at length. For the full picture of the loan product itself, start with the DSCR loan guide.
What DSCR do commercial lenders require in 2026?
Most commercial lenders require a minimum DSCR of 1.20x-1.25x on stabilized property in 2026: agency multifamily underwrites near 1.25x, banks typically want 1.20x-1.30x depending on asset class, and some small-balance commercial DSCR programs accept ratios near 1.00x at reduced leverage and higher pricing.
Requirements move with asset class (hotels price to higher coverage than apartments), market, and the lender's own book. The full 2026 threshold map — ratios by property type, credit score floors, and reserve requirements — is in our companion guide to DSCR loan requirements, and the underwriting quirks specific to 5-20 unit buildings get their own treatment in DSCR loans for small multifamily.
How can you improve a property's DSCR before applying?
You can improve DSCR from either side of the fraction: raise underwritable NOI — documented rent increases, other income, expense reductions that survive diligence — or shrink the debt service with a longer amortization, a rate buydown, or simply a smaller loan. Structure can help too, but only with lenders that underwrite the interest-only payment.
A caution on the amortization lever: it moves the ratio more than people expect, and not every lender offers it. Compressing the example loan to a 25-year schedule raises annual debt service from $233,495 to $248,728 — dropping the DSCR from 1.20x to 1.13x — so the difference between a 25-year and a 30-year lender can be the difference between an approval and a decline before pricing is even discussed. The honest levers, though, are the income ones: at a 1.25x requirement and a 0.0778 constant, every extra dollar of documented NOI supports roughly ten more dollars of loan — which is why cleaning up the rent roll and the expense story before underwriting is the highest-yield hour a borrower spends.
The bottom line
DSCR for a commercial property loan is annual NOI divided by annual principal and interest — but the working version of the formula is the lender's: underwritten NOI with vacancy floors, imputed management, and reserves, divided by a payment that may be the amortizing one even during an IO period, then run backward to size the loan. On the worked example, $280,800 of NOI carries a $3,000,000 loan at 1.20x and supports about $2.89 million at a 1.25x requirement. The inputs are negotiable and the thresholds vary by shop, which makes coverage a shopping problem as much as a math problem. Package the deal once on YieldStack and let programs that fit your DSCR compete →