How to use
- Enter the loan amount, annual interest rate and term. The term can be in years or months.
- Pick a repayment type — amortizing, equal principal or interest-only. The monthly payment, total interest and total repayment update instantly.
- Scroll the schedule for each payment’s principal, interest and remaining balance, or use Copy table to paste it into a spreadsheet.
The calculator works with any currency; amounts are shown with two decimal places.
Repayment types and formulas
P = loan amount, r = monthly rate (annual rate ÷ 12), n = number of monthly payments.
| Type | What you pay each month | Formula |
|---|---|---|
| Amortizing (level payment) | The same amount every month | M = P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1). Early payments are mostly interest; later ones are mostly principal |
| Equal principal | Highest at first, then declining | P ÷ n of principal + remaining balance × r |
| Interest-only (bullet) | Interest only, then the full principal at the end | P × r each month; the last payment is P + P × r |
Each payment is rounded to the cent, and any rounding difference is settled in the final payment so the balance ends at exactly zero. A 0% rate simply splits the principal evenly across the term.
Example: 300,000 at 6.5% for 30 years
| Type | First payment | Last payment | Total interest |
|---|---|---|---|
| Amortizing | 1,896.20 | 1,900.91 | 382,636.71 |
| Equal principal | 2,458.33 | 839.05 | 293,313.66 |
| Interest-only | 1,625.00 | 301,625.00 | 585,000.00 |
Paying principal down faster shrinks the balance that interest is charged on, so total interest falls. The amortizing schedule’s last payment is slightly larger because the fraction of a cent dropped from each of the 360 payments is collected at the end.
Things to keep in mind
- Results are for reference only. Lenders differ in how they accrue interest (some use actual days in each period) and how they round, so your statements may not match to the cent. Your loan agreement is the final word.
- A typical US mortgage payment can also include property tax and insurance held in escrow. This calculator covers principal and interest only.
- Variable-rate loans change payments when the rate resets; this tool assumes one fixed rate for the whole term. Fees, grace periods and prepayment penalties are not included.
- To see how savings grow instead, try the compound interest calculator.
FAQ
Which costs less overall: amortizing or equal principal?
Equal principal, at the same rate and term — the balance drops faster, so less interest accrues. The trade-off is a much higher payment in the first years.
Why does an interest-only loan cost the most interest?
The full principal stays outstanding until the final month, so every month’s interest is charged on the whole amount.
Is anything I enter saved or sent anywhere?
No. All calculations run in your browser.