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Loan Calculator

Work out the monthly payment, total interest and full cost of any fixed-rate loan.

Result —

About this calculator

A loan calculator is the fastest way to find out what a personal, auto or business loan will really cost. By comparing different terms and interest rates side by side you can pick a payment that fits your budget without paying for years of unnecessary interest.

How it works

The math behind a fixed-rate loan is identical to a mortgage: a constant monthly payment is split into an interest portion (calculated on the remaining balance) and a principal portion (which reduces the balance for next month). Over time the interest share shrinks and the principal share grows.

Interest rates and term length are the two biggest levers. Doubling the term roughly halves the monthly payment but can more than double the total interest paid. A small reduction in rate compounds across every payment.

Personal loans usually run from 12 to 84 months. Auto loans often stretch to 96 months but the vehicle depreciates much faster than the balance shrinks, which is why long auto loans can put borrowers underwater on their car.

Always check whether the lender charges origination fees or prepayment penalties — those don’t show up in the headline rate but they can change the true cost meaningfully.

Formula

Monthly payment = P · i / ( 1 − (1 + i)^−n )

P = principal
i = monthly rate = annual rate / 12
n = number of monthly payments

Examples

5-year personal loan at 8%

Borrowing 15,000 at 8% for five years costs about 304 per month and roughly 3,249 in interest over the full term.

Result: Monthly payment ≈ 304.15 — total interest ≈ 3,249

3-year loan at the same rate

Cutting the term to three years raises the monthly cost by about 166 but reduces total interest by more than 40%.

Result: Monthly payment ≈ 469.97 — total interest ≈ 1,919

Frequently asked questions

Does this calculator work for auto and personal loans? +
Yes — the math is the same for any fixed-rate, fully amortizing loan. Just enter the amount, rate and number of months.
Are origination fees included? +
No. Add origination fees to the principal if you want to see your true effective cost, or compare lenders by APR rather than rate alone.
Can I pay the loan off early? +
Usually yes, but a few lenders charge a prepayment penalty. Always check the loan agreement — paying down high-interest debt early is one of the best returns you can earn.
How is interest charged? +
Most fixed-rate loans use monthly simple interest on the outstanding balance. Each payment first covers the interest accrued that month, then reduces the principal.
What rate should I use if my lender quotes APR? +
If the APR includes only the interest rate (no extra fees), use it directly. If it bundles fees, the calculator will slightly overstate the cost of credit.

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