Loan Calculator
Monthly payment, total interest and the full amortization story — for mortgages, car loans and personal loans. Calculated on your device, sent nowhere.
Amortization by year
| Year | Principal paid | Interest paid | Remaining balance |
|---|
Your files never leave your device.
How to use the loan calculator
- Enter the amount you want to borrow — the price after your down payment for a mortgage, or the full amount for a personal loan.
- Enter the annual interest rate as a percentage (for example 4.5 for 4.5%).
- Enter the term in years. Results — monthly payment, total interest, total paid and the year-by-year schedule — update as you type.
Understanding your numbers
Monthly payment is the fixed amount you pay every month for the whole term. Fixed-rate loans are structured so this number never changes, even though the split inside it does.
Total interest is what borrowing costs you over the full term: total paid minus the amount borrowed. This is the number that shocks people most — a 25-year loan at 4.5% pays roughly half the original amount again in interest. It's also the number that a shorter term or extra payments attack hardest.
The amortization schedule shows why. Every payment covers the interest accrued that month first; only the remainder reduces the principal. In year one of a long mortgage, most of each payment is interest. As the balance shrinks, so does the interest portion, and by the final years almost the entire payment goes to principal. Watch the "Interest paid" column fall year over year — that's your loan maturing.
The formula, in plain terms
The calculator uses the standard annuity formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the amount borrowed, r the monthly rate (annual rate divided by 12) and n the number of monthly payments. It is the same formula your bank uses, and the same one behind spreadsheet functions like PMT().
When to use it
- House hunting — turn "can I afford this price?" into a concrete monthly number before you fall in love with a listing.
- Comparing offers — a lower rate over a longer term can still cost more in total interest; compare the total interest line, not just the payment.
- Car and personal loans — see how the term length trades payment size against total cost.
- Debt payoff planning — model a shorter term to see what paying it off faster saves you.
Frequently asked questions
What formula does the loan calculator use?
The standard fixed-payment annuity formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the amount borrowed, r the monthly interest rate (annual rate ÷ 12) and n the number of monthly payments. This is the same formula banks use for fixed-rate loans.
Does the result include taxes, insurance or fees?
No. The calculator covers principal and interest only. Property taxes, home insurance, mortgage insurance, origination fees and closing costs are extra — add them separately when budgeting.
What is an amortization schedule?
A table showing how each payment is split between interest and principal over the life of the loan. Early payments are mostly interest; near the end they are mostly principal. The schedule above summarizes this year by year with your remaining balance.
What happens if I make extra payments?
Extra payments applied to the principal reduce the balance that interest is charged on, so you pay less total interest and finish earlier. This calculator models the standard fixed schedule; try lowering the term to see the effect of paying faster.
Is my data private?
Yes. Calculations run entirely in your browser. Nothing is uploaded, logged or stored anywhere.