Loan Calculator
A loan of 100,000 at 6% a year over 30 years costs 599.55 a month and 115,838.19 in total interest.
How to use
- Enter the loan amount, the yearly interest rate in percent, and the term in years or months.
- Pick a repayment method: equal payments, equal principal, or interest only with the principal due at the end.
- Read the payment and the total interest, then scroll the schedule to see principal, interest and balance for every month. Copy the schedule into a spreadsheet if you need it.
How it works
Monthly rate r = annual rate ÷ 100 ÷ 12. Number of payments n = term in months.
Equal payments: payment = P · r / (1 − (1 + r)^−n). Each month the interest is the balance times r and the rest of the payment reduces the balance. At 0% the payment is simply P ÷ n.
Equal principal: every month repays P ÷ n of principal plus interest on the remaining balance, so the first payment is P ÷ n + P · r and payments fall each month.
Interest only: every month pays P · r, and the last month pays P · r plus the whole principal P.
Total interest = total of all payments − P. The last row always ends at a balance of exactly zero. Amounts are computed at full precision and rounded to two decimals only for display.
The three repayment methods compared
Same loan for each row: 100,000 at 6% a year over 10 years (120 monthly payments). Amounts are plain numbers in any one currency.
| Method | First payment | Last payment | Total interest | Total paid |
|---|---|---|---|---|
| Equal payments | 1,110.21 | 1,110.21 | 33,224.60 | 133,224.60 |
| Equal principal | 1,333.33 | 837.50 | 30,250.00 | 130,250.00 |
| Interest only | 500.00 | 100,500.00 | 60,000.00 | 160,000.00 |
Which method fits
- Equal payments (annuity): the same amount every month. Easy to budget; early payments are mostly interest.
- Equal principal: the principal part is the same every month, so payments start higher and fall. You pay less total interest than with equal payments.
- Interest only (bullet): you pay only the interest each month and repay the whole principal in the last month. Monthly cost is lowest, total interest is highest, and you need the principal ready at the end.
What the calculator assumes
- The rate is a nominal annual rate. Each month the interest is the balance times the annual rate divided by 12.
- Payments are monthly, in arrears, with the first one a month after the loan starts.
- No fees, insurance, variable rates, prepayments or grace periods are included. Real contracts differ, and rounding rules differ between lenders, so the figures are an estimate, not an offer.
Last reviewed 2026-10-13
FAQ
What is the difference between equal payments and equal principal?
Equal payments keep the monthly amount constant, with more interest in the early months. Equal principal repays the same slice of principal every month, so the first payments are higher and shrink, and the total interest is lower.
Can I enter the term in months?
Yes. Switch the unit to months, for example 18 months, or enter years such as 2.5 which is 30 months. The term must come to a whole number of months, up to 1,200.
Why is the total interest so large on a long loan?
Interest is charged on the outstanding balance every month, and on a long loan the balance stays high for years. Halving the term often cuts total interest by more than half.
Is the rate an APR?
No. It is a nominal annual rate divided by 12 for each month. An APR also folds in fees and compounding, so use the contract rate here and expect small differences from a lender quote.
Does it include fees or insurance?
No. It covers interest and principal only. Origination fees, insurance, taxes, variable rates and early repayment are outside this calculator.
Which currency does it use?
Any. Enter plain numbers in one currency and read the result in the same one. There is no currency symbol to set.