Loan Payment Calculator
Calculate monthly debt service payments for fixed-rate commercial real estate loans.
Work out the monthly and annual debt service on a fixed-rate commercial loan, plus total interest over the term. Annual debt service is the figure that feeds every coverage test a lender runs, so it is usually the number you want first.
Set to 0 for fully amortizing payments from month 1
The formula
Payment = P x [ r(1+r)^n ] / [ (1+r)^n - 1 ] P = loan amount, r = monthly rate (annual / 12), n = amortisation months
What to watch
- Amortisation period and loan term are different things. A ten-year loan with thirty-year amortisation is paid down at a thirty-year pace and has a balloon at year ten.
- Longer amortisation lowers the payment, which raises the loan a given NOI can support at the same coverage ratio. This is the main structural lever on a coverage-constrained deal.
- An interest-only period lowers the payment further but builds no equity, and lenders test coverage against the amortising payment in many cases.
- For floating-rate debt, run the payment at a stressed rate rather than today's rate — that is how a lender will size it.
Frequently asked questions
What is annual debt service?
The total of twelve monthly principal-and-interest payments. It is the denominator in the debt service coverage ratio, so it is the figure lenders use to test whether the property's net operating income supports the loan.
Should I use the loan term or the amortisation period?
Use the amortisation period to calculate the payment, and the loan term to know when the balloon falls due. A ten-year loan amortising over thirty years has payments based on thirty years and an outstanding balance due at year ten.
Go deeper
How Lenders Size Your Loan: DSCR, Debt Yield, and LTV
Three constraints determine your loan proceeds, and only one of them binds. Knowing which one — before you go to market — is the difference between a realistic raise and a wasted month.
Read the articleThis calculator produces estimates from the assumptions you enter. It is not investment, tax, or legal advice, and actual lender terms, pricing, and outcomes will differ. Confirm anything you intend to rely on with advisers engaged on your specific facts.
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