Compound Interest Calculator
A compound interest calculator shows how money grows when interest earns interest. $10,000 at 5% compounded monthly becomes…
Loan Calculator
A loan calculator shows the fixed monthly payment on an amortizing loan and how much interest you pay in total. Borrowing $10,000 at 8% for 5 years costs $202.76 a month and $2,165.84 in interest. Add any upfront fee to see the loan’s true APR.
How to use the loan repayment calculator
- Enter the amount. Type the amount you want to borrow, before any fee is taken off.
- Add the interest rate. Use the annual interest rate from your quote. If the lender only quotes an APR and no separate rate, enter the APR and leave the fee blank.
- Choose the term. Enter the length of the loan and pick years or months. Personal loans usually run 1–7 years.
- Add the fee. If there is an arrangement or origination fee, enter it to see the APR including that fee.
- Compare. Read the note under your result to see what a term one year shorter or longer would cost, then open the schedule.
What a personal loan calculator tells you
Most personal loans, car loans and student loans are amortizing: you pay the same amount every month, and each payment covers that month’s interest plus a slice of the balance. The calculator gives you three numbers that matter when you compare offers:
- Monthly payment: the amount that has to fit your budget every month.
- Total interest: what the loan actually costs you, in money rather than percentages.
- APR: the yearly cost including fees, which is the fairest way to compare two lenders.
On a $10,000 loan at 8% over 5 years, the first payment of $202.76 splits into $66.67 of interest and $136.10 of principal. By the final year almost all of each payment goes to principal.
The loan payment formula
The fixed payment comes from the standard amortization formula:
Payment = P × r ÷ (1 − (1 + r)−n)
- P is the amount borrowed
- r is the monthly rate: annual rate ÷ 12 ÷ 100
- n is the number of monthly payments
For $10,000 at 8% over 60 months, r = 0.006667 and the payment is $202.76. Multiply by 60 and subtract the $10,000 borrowed to get the $2,165.84 of interest.
How the term changes your payment and interest
A longer term lowers the monthly payment but you pay interest for longer. Here is the same $10,000 at 8%:
| Term | Monthly payment | Total interest |
|---|---|---|
| 3 years | $313.36 | $1,281.09 |
| 4 years | $244.13 | $1,718 |
| 5 years | $202.76 | $2,165.84 |
| 6 years | $175.33 | $2,624 |
| 7 years | $155.86 | $3,092.42 |
Stretching from 3 to 7 years cuts the payment by half but more than doubles the interest. Choose the shortest term whose payment you can comfortably afford, and keep a buffer for months when money is tight.
Using it as a loan interest calculator: why the rate matters
Rates on unsecured loans vary much more than mortgage rates because they depend on your credit history. On a $5,000 loan over 2 years:
| Rate | Monthly payment | Total interest |
|---|---|---|
| 12% | $235.37 | $648.82 |
| 18% | $249.62 | $990.89 |
| 24% | $264.36 | $1,344.53 |
Doubling the rate from 12% to 24% roughly doubles the interest, yet the monthly payment only rises by about $29. That is why comparing loans on monthly payment alone can hide a much more expensive deal.
APR vs interest rate: the loan APR calculator explained
The interest rate is what the lender charges on the balance. The annual percentage rate (APR) also counts fees, so it shows the true yearly cost. US lenders must disclose APR under the Truth in Lending Act, and UK lenders must show a representative APR under FCA rules.
Fees matter because you pay interest on money you never receive. Borrow $20,000 at 7% for 5 years with a $600 fee taken from the loan and you receive $19,400 but repay $396.02 a month on the full $20,000. That makes the APR 8.29%, not 7%. The tool finds that APR by solving for the rate at which your payments exactly repay the money you actually received.
Remember that a representative APR in the UK only has to be offered to 51% of successful applicants. Your personal rate may be higher, so always re-run the numbers with the rate you are actually offered.
Ways to pay less interest
- Borrow less. Every $1,000 you don’t borrow at 8% over 5 years saves about $217 in interest.
- Shorten the term if the payment still fits your budget comfortably.
- Improve your credit first. Paying bills on time and lowering card balances can move you into a cheaper rate band.
- Check for early repayment charges. Many personal loans let you overpay. In the UK, the early settlement charge on a regulated loan is capped at 1% of the amount repaid early (0.5% if less than a year is left) under the Consumer Credit Act.
- Compare the total cost of credit, not just the monthly payment.
Loan calculator FAQs
What is the monthly payment on a $15,000 loan?
At 6.5% over 4 years, a $15,000 loan costs $355.72 a month and $2,074.77 in total interest. Over 5 years at 9.5%, a $25,000 loan costs $525.05 a month.
Does this work for car loans and student loans?
Yes, for any fixed-rate loan repaid in equal monthly instalments. It does not model balloon payments, deferred payments or income-driven repayment plans.
Why is my lender's payment slightly different?
Lenders may round each payment, charge interest daily rather than monthly, or start the first payment more or less than a month after the loan is paid out. The difference is usually a few cents to a few dollars.
What is a good APR for a personal loan?
It depends on your credit score and the market. Compare offers from several lenders using the APR and total cost of credit shown here, rather than relying on a rule of thumb.
Is it better to choose a shorter loan term?
A shorter term always costs less interest, but a higher payment you struggle to meet is worse than paying a little more interest. Pick the shortest term that leaves room in your monthly budget.
Sources and methodology
Payments use the standard amortization formula with monthly compounding. The schedule is computed month by month, with the final payment adjusted to clear the balance exactly. APR including fees is found numerically (bisection) as the monthly rate at which the payments repay the amount actually received, multiplied by 12. All example figures on this page were produced by this calculator.
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