About this tool
DSCR Calculator is a free, in-browser tool that computes the debt service coverage ratio lenders use to qualify rental-property loans. Enter the monthly rent, a vacancy allowance, monthly operating expenses and the loan terms, and it returns the DSCR along with net operating income and annual debt service. All math runs locally on your device — nothing is uploaded.
Net operating income is annualized: NOI = rent × 12 × (1 − vacancy ÷ 100) − operating expenses × 12. The mortgage payment uses the standard amortization formula M = L·r ÷ (1 − (1+r)⁻ⁿ) with r = rate ÷ 1200 and n = term × 12; annual debt service is M × 12. The ratio is DSCR = NOI ÷ annual debt service.
A DSCR of 1.00 means the property's income exactly covers its loan payments; most DSCR lenders want at least 1.25, and the tool flags a pass or fail against that threshold. Use it to pre-screen a rental before applying, or to see how a bigger down payment (lower loan) or lower rate lifts the ratio.