What DSCR measures
The debt service coverage ratio is net operating income divided by annual debt service — the total of the year’s principal and interest payments. A DSCR of 1.25x means the building produces $1.25 of NOI for every $1.00 of mortgage payments, leaving a 25% cushion before income falls short of the loan.
For commercial and multifamily lenders, DSCR is usually the constraint that matters most. Your credit and net worth still count, but the building has to carry the loan on its own income. If the coverage is too thin, the lender reduces the loan amount until it is not.
How the calculator works
The calculator runs the same steps a loan underwriter would:
- Annual debt service on an amortizing loan uses the standard mortgage payment formula on the loan amount, monthly rate and number of payments, multiplied by twelve.
- For an interest-only loan, annual debt service is the loan amount multiplied by the interest rate.
- DSCR is NOI divided by annual debt service.
- Maximum loan at your target DSCR divides NOI by the target to find the most debt service the income supports, then converts that payment back into a loan amount at the same rate and term.
- Debt yield is NOI divided by the loan amount — a measure some lenders use alongside DSCR because it does not depend on the interest rate.
- Break-even shows how far NOI could fall before it no longer covers the payments.
A worked example
A building produces $180,000 of NOI. The buyer wants a $2,000,000 loan at 6.25% amortized over 30 years. Monthly payments are about $12,314, or about $147,800 a year, for a DSCR of roughly 1.22x.
If the lender requires 1.25x, the income supports about $144,000 of annual debt service, which works out to a maximum loan of about $1,949,000 — some $51,000 less than requested. The buyer can bring more equity, negotiate the price, look for a lower rate or longer amortization, or find a lender whose interest-only period or program allows the full amount.
What lenders typically require
Requirements vary by lender, program, market and property. As a rough guide, agency lenders on stabilized multifamily often look for coverage around 1.20x to 1.25x on amortizing payments, banks and credit unions frequently set similar or slightly higher minimums, and bridge lenders on value-add deals may underwrite to lower coverage on current income because they are lending against a business plan. Lenders also set maximum loan-to-value ratios, and the loan you get is the smaller of the two limits.
Lenders calculate DSCR on their own version of NOI. They often apply their own vacancy factor, add a management fee even if you self-manage, include replacement reserves and use the property tax bill that will apply after the sale. Expect the lender’s DSCR to be lower than the one in the offering memorandum.
DSCR loans for smaller rentals
You may also see “DSCR loans” advertised for one- to four-unit rentals. These are investor loans that qualify the borrower on the property’s rent rather than personal income, often using gross rent divided by the mortgage payment plus taxes, insurance and association dues. The idea is similar, but the formula and thresholds differ from commercial multifamily underwriting, so confirm which version a lender is using.
Why coverage matters after closing
Many loan agreements include DSCR covenants that are tested periodically. If coverage drops below a set level, the lender may require cash to be held in reserve, restrict distributions to owners or, in serious cases, treat the shortfall as a default. That is why rising insurance and property tax bills, or a floating-rate loan whose payment climbs, can create problems for a building whose income has not changed at all. Underwriting with a cushion is cheaper than finding one later.
