Skip to content

How to Calculate DSCR, With Worked Examples

Step-by-step DSCR math for a single rental and a small apartment building, plus the adjustments lenders make that change your ratio.

DSCR loans6 min read

Debt service coverage ratio (DSCR) is the number that decides most rental property loans that don't rely on your personal income. The math takes a minute. Knowing which numbers a lender plugs in takes a little longer, and that's where most surprises come from.

All figures below are made-up illustrations to show the math. They aren't rates, terms, or quotes from any lender.

The formula

DSCR = income ÷ debt service

There are two common versions, and which one a lender uses depends mainly on the property type.

  • Residential rentals (1–4 units): monthly rent ÷ monthly PITIA. PITIA is principal, interest, taxes, insurance, and association (HOA) dues.
  • Commercial and larger multifamily (5+ units): annual net operating income (NOI) ÷ annual debt service. NOI is gross income minus operating expenses, before loan payments.

Example 1: a single-family rental

Say a house rents for $2,000 a month. With a proposed loan, the monthly payment breaks down like this:

  • Principal and interest: $1,250
  • Property taxes: $250
  • Insurance: $110
  • HOA dues: $40
  • Total PITIA: $1,650

DSCR = $2,000 ÷ $1,650 = 1.21

The rent covers the full payment with about 21% to spare. Many DSCR programs would consider that a qualifying ratio, though each sets its own minimum.

Now suppose the insurance quote comes back at $260 a month instead of $110. PITIA rises to $1,800, and DSCR drops to $2,000 ÷ $1,800 = 1.11. Same house, same rent, same loan, and a meaningfully weaker ratio. Get real tax and insurance numbers early.

Example 2: a 12-unit apartment building

For a small apartment building, lenders usually work from the property's operating statement:

  • Gross potential rent: $216,000 a year
  • Less vacancy and credit loss (5%): –$10,800
  • Effective gross income: $205,200
  • Less operating expenses (taxes, insurance, utilities, repairs, management, reserves): –$92,000
  • Net operating income: $113,200

If the proposed loan's payments total $90,000 a year:

DSCR = $113,200 ÷ $90,000 = 1.26

Commercial lenders often size the loan from the ratio. If a lender requires 1.25, the most annual debt service this property can support is $113,200 ÷ 1.25 = $90,560. That ceiling, together with the lender's leverage limit on value, sets the maximum loan.

Adjustments lenders make

Your spreadsheet and the lender's spreadsheet rarely match on the first try. Common adjustments:

  • Market rent vs. actual rent. For a vacant property or a purchase, lenders use the appraiser's market rent. For an occupied one, some use the lower of the lease or market rent.
  • Vacancy. Commercial lenders apply a vacancy factor even if the building is full today.
  • Management fees. Lenders often include a management fee even if you self-manage.
  • Replacement reserves. A per-unit annual reserve is commonly added to expenses.
  • Short-term rentals. Some lenders accept a history of short-term rental income, some discount it, and some won't use it at all.
  • Interest-only payments. On interest-only loans, some lenders calculate DSCR on the interest-only payment and some on a fully amortizing payment.

How to improve a thin ratio

If your numbers land just under a lender's minimum, the usual levers are:

  1. Borrow less. A larger down payment lowers the payment directly.
  2. Shop taxes and insurance. Especially insurance, which varies widely.
  3. Document the rent. A signed lease at or above market can help where a lender uses actual rent.
  4. Change the structure. A different amortization or loan type changes the payment in the ratio.
  5. Try another lender. Minimums and adjustments vary. A deal one lender turns down can fit another's guidelines.

Put it together

Run both your own number and a conservative one: lower rent, higher insurance, the lender's vacancy and management assumptions. If the conservative version still works, the deal is probably financeable. For the bigger picture on how these loans work, see What Is a DSCR Loan?

This article is general education, not an offer to lend or a quote. Example figures are illustrations only. Rates, terms, and approval are set by each lender and depend on the property, the borrower, and market conditions.

Keep reading