The DSCR formula
DSCR = net operating income ÷ annual debt service
Net operating income is rent minus vacancy and operating expenses. Annual debt service is twelve months of principal and interest. A DSCR of 1.00 means the property earns exactly enough to pay the loan. At 1.25, it earns 25% more than the payments.
A worked example
With $2,400 rent, 5% vacancy and $9,000 of operating expenses, NOI is $18,360. A $180,000 loan at 7% over 30 years costs about $1,198 a month, or $14,371 a year. DSCR is $18,360 ÷ $14,371 = 1.28.
What lenders want to see
Minimums of 1.20 to 1.25 are common for investment property loans, and some programs go lower with a larger down payment or a higher rate. Requirements vary by lender.
Be aware that many DSCR loan programs use a simpler version of the ratio: gross rent divided by the full monthly payment including taxes, insurance and HOA dues. Ask your lender which calculation they use before you rely on a number.