Always ask what the lender means by income and debt service. Identical ratio labels can hide different calculations.
The debt-service coverage ratio, or DSCR, expresses operating income relative to scheduled debt payments. It gives a quick view of coverage, but its usefulness depends on the definitions behind both numbers. Confirm those definitions before comparing your worksheet with a lender’s underwriting result.
Calculate the NOI-based ratio
RentWise divides annual NOI by annual principal-and-interest debt service. With $24,000 NOI and $18,000 debt payments, the result is 1.33× when rounded. In this simplified model, each dollar of annual debt payment has approximately $1.33 of operating income behind it.
A ratio of 1.00 means the two entered amounts are equal. Below 1.00, operating income falls short of debt service before considering costs excluded from NOI, such as your separate capital reserve. Coverage above 1.00 does not by itself mean all cash obligations are comfortably funded.
Use matching periods and consistent income
Do not divide monthly income by annual debt service. Both values must represent the same period. RentWise labels its inputs and capacity outputs annually, so multiply monthly amounts by twelve before entering them.
Build NOI from effective income after vacancy and collection allowances, less recurring operating expenses. Avoid using gross rent merely because it is easy to find. If the lender uses an adjusted expense allowance or another income definition, calculate that figure separately and document the difference.
Explore a target without treating it as approval
Suppose you select a 1.25× target. Dividing $24,000 NOI by 1.25 gives $19,200 of supported annual debt service under this method. That is $1,600 monthly, but it is not a loan amount. Converting payment capacity into borrowing also requires rate and term assumptions.
Other underwriting constraints can limit borrowing even when the ratio reaches a target. Property value, leverage, reserves, borrower documentation, and lender policy may matter. The target here is a scenario input, not a promised requirement or an offer.
Stress-test the operating margin
If NOI falls from $24,000 to $21,000 while debt service remains $18,000, coverage drops from 1.33× to 1.17×. At a 1.25× target, supported annual debt service falls from $19,200 to $16,800. The existing debt payment does not shrink automatically.
Investigate plausible changes in rent collection, insurance, property taxes, routine repairs, and management costs. A ratio built on optimistic income may look comfortable while leaving very little flexibility in a weaker year.
Recognize alternative residential methods
Some residential lending products use rental income compared with principal, interest, taxes, insurance, and association charges, sometimes called PITIA. That approach is not interchangeable with NOI divided by principal and interest. Using the same rent or expense twice can distort a comparison.
Use the DSCR calculator only when its stated method matches the question you are answering. If a lender gives a different definition, use their written worksheet or ask them to explain how they reconcile the figures. A familiar label should not replace that check.
Common questions
Is 1.25× a universal minimum?
No. It is an illustrative target in this tool. Thresholds and definitions depend on the lender and product.
Why is a capital reserve not inside NOI here?
RentWise separates it from recurring operating expenses. An underwriter may handle reserves differently, which changes the income available for their coverage test.
Can an unlevered property have DSCR?
With zero debt service the ratio is undefined rather than a finite number. Use cap rate and cash-flow measures for a property without debt.
Make the numbers yours.
Use your own inputs, review the assumptions, and compare a second scenario.
Try the dscr toolPrepared with AI assistance and numerical examples. No professional financial review is claimed. Read our editorial approach or suggest a correction.