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Personal Loan Calculator

Enter the loan amount, interest rate, and term to see your monthly payment, total interest paid, and total repayment cost. Adjust rate and term together to find the combination that fits your monthly budget and minimises total interest.

Last reviewed May 18, 2026 by ToolSpilo Editorial Team.

Review method: Reviewed against the implemented calculator logic and current CFPB consumer-finance guidance on payments, interest, debt, and borrowing caveats.

For informational purposes only. Not financial, investment, or tax advice. Results are estimates based on the inputs provided. Consult a qualified financial professional before making financial decisions.

Calculator tool

How this calculator works

Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.

The Monthly Payment Formula (PMT)

Personal loans use fixed amortized payments — each month the payment is identical, but the split between interest and principal shifts over the life of the loan.

PMT=P×r(1+r)n(1+r)n−1\text{PMT} = P \times \frac{r(1+r)^n}{(1+r)^n - 1}
  • PP = loan principal (amount borrowed)
  • rr = monthly interest rate = annual rate ÷ 12
  • nn = total number of monthly payments = term in years × 12
  • Total interest = PMT × nn − PP

Worked Example — USD 15,000 Loan at 10% for 3 Years

Monthly rate: r=10%÷12=0.8333%r = 10\% ÷ 12 = 0.8333\%
Payments: n=3×12=36n = 3 \times 12 = 36

PMT=15,000×0.00833×(1.00833)36(1.00833)36−1≈$483.82\text{PMT} = 15{,}000 \times \frac{0.00833 \times (1.00833)^{36}}{(1.00833)^{36} - 1} \approx \$483.82
  • Total repaid: USD 483.82 × 36 = $17,417.52
  • Total interest: USD 17,417.52 − USD 15,000 = $2,417.52
  • Interest as % of loan: 16.1%

Rate vs Term Tradeoff — USD 15,000 Loan

RateTermMonthly PaymentTotal Interest
8%2 yrUSD 679.16USD 1,299.84
10%3 yrUSD 483.82USD 2,417.52
12%4 yrUSD 395.07USD 3,963.36
15%5 yrUSD 356.79USD 6,407.40

Extending from 3 to 5 years at a higher rate cuts the monthly payment by USD 127 but costs an additional USD 3,990 in interest — nearly 27% of the original loan amount.

APR vs Stated Interest Rate

Personal loan lenders often advertise an interest rate but are legally required to disclose the APR (Annual Percentage Rate), which includes origination fees, processing charges, and any mandatory insurance. A loan at 10% stated rate with a 3% origination fee has an effective APR closer to 11.5–12% depending on term. Always compare APR across lenders, not stated rates.

Compare APR, not stated rate: A lender advertising 9% with a 3% origination fee can cost more than a lender advertising 11% with no fees — depending on how long you hold the loan. The APR folds in all costs into one comparable number. It is usually the better basis for comparing borrowing cost than the stated rate alone.

Frequently asked questions

How is personal-loan interest calculated each month?

Interest accrues on the remaining principal at the monthly rate. The fixed payment first covers that month's interest, and the rest reduces principal, so early payments are more interest-heavy than later ones.

What affects the APR I am offered?

Lenders commonly consider credit history, income, existing debt, loan amount, term, and fees. Compare actual prequalified APR quotes rather than relying on a generic rate range, because the relevant offer is the one available to your profile today.

Is early payoff always free?

Not always. Some loans allow extra payments freely, while others include prepayment rules or fees. Check the loan agreement before assuming an early-payoff plan will save the full modeled interest.

Why compare APR instead of only the stated rate?

APR folds required borrowing costs into a more comparable annual figure. A loan with a lower stated rate can still cost more if mandatory fees are higher.