How to calculate a monthly loan payment
✓ Verified in LibreOffice 25.8.7.3 ✓ Verified in Google Sheets (2026-08-30)Work out the monthly payment for a loan or mortgage from rate, term, and amount.
The formula
| App | Formula | Notes |
|---|---|---|
| Excel (desktop) | =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. We then ran the same formulas in Google Sheets, executed 2026-08-30: a formula-only workbook goes into Google Drive, which converts it to a Sheet and recalculates every formula with Google’s own engine, and comes back out as .xlsx carrying the values Google computed. It returned 1798.65 for the worked example, the same value LibreOffice produced. Both engines’ numbers on this page are executed results. The Excel formula follows Microsoft’s official documented syntax — we do not run desktop Excel.
Functions used
ROUND · PMT — see full Excel, Google Sheets & LibreOffice compatibility for each.
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