Amortization Calculator
Enter a loan amount, rate and term to see the monthly payment, the total interest, and a year-by-year schedule of how each payment splits between principal and interest. Add an optional extra payment to see how much time and interest it saves. It works in any currency, for any fixed-rate loan.
Why the split changes over time
With a fixed-rate loan you pay the same amount every month, but what that payment does changes. Interest is charged on the balance, which is largest at the start, so early payments are mostly interest and barely dent the principal. As the balance falls, the interest portion shrinks and more of each payment goes to principal — which is why, in the schedule above, the principal-paid column climbs every year while the balance drops toward zero.
Worked example
A $300,000 loan at 6.5% over 30 years has a monthly payment of about $1,896 and costs roughly $382,600 in interest — more than the amount borrowed. In year one only about $3,300 of your payments reduces principal; by the final year almost all of it does. Add an extra payment above to watch both the payoff time and that interest total fall.
The power of a small extra payment
- Every extra dollar goes to principal, removing all the future interest that dollar of balance would have accrued — so extra payments early in the loan are worth the most.
- Even a modest monthly extra can cut years off a 30-year mortgage and save tens of thousands in interest; the saving line above shows your exact figures.
- Check for prepayment penalties on your loan before committing to extra payments — most modern mortgages allow them freely.
Methodology & assumptions
The monthly payment uses the standard amortization formula. Each month, interest = balance × (annual rate ÷ 12) and the remainder of the payment reduces principal; the table aggregates principal and interest by year and shows the year-end balance. Extra payments are applied to principal each month. It assumes a fixed rate, no fees, and no changes to the payment; taxes and insurance (for a mortgage) are excluded. It is a planning estimate — your statement may differ slightly if the lender compounds daily. See our methodology and editorial policy.
Frequently Asked Questions
Does this work for a car or personal loan?
Yes — the same amortization math applies to any fixed-rate installment loan. Just enter that loan's amount, rate and term.
Why is my total interest more than the loan?
On a long term at a typical rate, accumulated interest can exceed the amount borrowed. A shorter term or extra payments cut it sharply.
Where do taxes and insurance fit?
They're not part of amortization — they're added to a mortgage payment separately. This tool shows principal and interest only.
Thinking about a lower rate?
See whether refinancing saves money after closing costs, and when it breaks even.
Open the refinance calculator →Related calculators
Sources
Uses the standard loan amortization formula and reducing-balance interest math. Figures are estimates for planning, not a lender statement — confirm terms with your lender. See our methodology and editorial policy.