How to calculate a monthly loan payment
✓ Verified in LibreOffice 25.8.7.3Work out the monthly payment for a loan or mortgage from rate, term, and amount.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel | =ROUND(PMT(A2/12,B2*12,-C2),2) | A2=annual rate, B2=years, C2=loan amount. The minus sign makes the payment positive. |
| Google Sheets | =ROUND(PMT(A2/12,B2*12,-C2),2) | Identical. |
| LibreOffice Calc | =ROUND(PMT(A2/12,B2*12,-C2),2) | Identical. |
How it works
PMT(rate, periods, present_value) computes the fixed payment: divide the annual rate by 12 and multiply years by 12 to work in months. A $300,000 loan at 6% over 30 years costs $1,798.65 a month. PMT follows cash-flow sign convention — money you receive (the loan) and money you pay have opposite signs, hence -C2 to get a positive payment. Total interest is simply payment × months − principal: here about $347,515.
Verified, not just documented
We ran =ROUND(PMT(A2/12,B2*12,-C2),2) in LibreOffice 25.8.7.3 (headless, with forced recalculation) and it returned 1798.65 — exactly the expected result. Every formula here is confirmed by actually executing it.