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Loan Payment Calculator: Monthly Cost and Total Interest
The monthly number is the easy part. The total is the one that matters.
Enter the amount borrowed, the annual interest rate and the term, and you'll get the monthly payment — plus the number lenders rarely lead with: the total interest across the whole loan.
That second figure is where the decision usually lives. Stretching a loan over more years lowers the monthly payment, which feels like winning, while quietly increasing what the loan costs in total. Try the same amount over different terms and watch the two numbers move in opposite directions — it's the clearest way to see the trade you're actually being offered.
Good to know
Why does a longer term cost so much more?
Because interest is charged on the outstanding balance for every month it stays outstanding. Adding years lowers each payment but leaves a larger balance in place for longer, so the total interest rises — often dramatically on long mortgages.
Does this include fees, taxes and insurance?
No. It calculates principal and interest only. Property taxes, insurance and arrangement fees are real costs on top, which is why the APR of a loan is usually higher than its headline interest rate.
What happens if I overpay each month?
Every extra unit goes straight at the principal, which reduces the balance all future interest is calculated on. Overpayments made early in the term remove far more total interest than the same amount paid near the end.
Fixed or variable rate?
A fixed rate makes this calculation reliable for the whole term; a variable one makes it a snapshot of today only. That predictability is the thing you're paying for with a fixed rate, and whether it's worth it depends on how much a rise would hurt you.