Tools / Loan Calculator
Loan & Mortgage Calculator
Monthly payment, total interest and a year-by-year amortization schedule — for both annuity and equal-principal loans, with optional extra payments.
Principal and interest only — taxes, insurance and fees are not included. Any currency works.
Principal vs interest
Payment split by year
| Year | Paid | Principal | Interest | Remaining balance |
|---|
The formulas
- P is the principal, r the monthly rate (annual rate ÷ 12) and n the number of months.
- Annuity keeps the payment flat; the interest share shrinks and the principal share grows every month.
- Equal principal repays the same principal amount every month, so the first payments are the highest — and total interest is lower.
- Extra payments go straight to principal and shorten the term.
Which repayment type should you pick?
If cash flow is tight early on, annuity (fixed payment) is easier to plan around. If you can afford a higher first payment and want to pay less interest overall, equal principal wins. The difference over 30 years is often tens of thousands — use the calculator above to see it with your own numbers before deciding.
FAQ
Annuity or equal principal — which costs less?
Equal principal always costs less in total interest, because you pay down the balance faster. The trade-off is a higher first payment.
How much does an extra payment help?
Every extra unit goes entirely to principal, so it also removes all future interest on that amount. Small extras from year one have a disproportionate effect; the table above shows the shortened term.
Are taxes and insurance included?
No. For a mortgage, property tax and insurance are usually collected separately (escrow). Add them to the monthly figure yourself.
Does the rate stay the same for the whole term?
This assumes a fixed rate. For adjustable-rate loans, run the calculation again with the expected new rate for each period.
Is my data uploaded?
No — everything is computed in your browser and nothing is stored or sent.