Loan Amortization Calculator
Estimate a fixed-rate loan payment, total interest and payoff time when you add an extra monthly amount.
Set your values
Adjust the values, then calculate your result.
How to use Loan Amortization Calculator
- Enter the measurements or amounts in the fields above.
- Check that dimensions, rates and units match the labels.
- Select “Calculate loan payoff” to see a clear estimate and the formula used.
How the loan amortization calculator works
The base payment uses a fixed-rate amortization formula. The calculator simulates monthly interest and payments with the extra amount until the balance is paid.
Check your measurements and assumptions
Assumes a fixed rate, monthly payments, no fees, and no prepayment penalties. Actual lender methods and payment dates can differ; confirm terms before changing payments.
Review the estimate before you act
Compare this result with an independent measurement, supplier quote or institution guidance when the decision matters. Confirm that the units and assumptions match the labels above, and update the inputs when the conditions change. Keep a note of the values used so you can reproduce the estimate later. This calculator is a planning aid and does not replace professional, product-specific or local guidance.
Does paying extra reduce loan interest?
For a standard amortizing loan, extra principal payments can shorten payoff and reduce interest, subject to lender rules and fees.
Is input uploaded?
Processing takes place in your browser. This tool does not send your input or selected files to a conversion API.