How to use the Payment Calculator
The payment calculator solves two common questions: what monthly payment repays a balance in a set time, and how long a chosen payment will take.
What you need to enter
- Solve for
- Amount ($)
- Interest rate (%)
- Term (months)
- Monthly payment ($) (for time to pay off)
The formula
Payment = P × r ÷ (1 − (1 + r)^−n). Time to pay off = −ln(1 − P × r ÷ payment) ÷ ln(1 + r), with r the monthly rate.
Worked example
Using the default values in the calculator:
- Solve for: Monthly payment
- Amount ($): 20000
- Interest rate (%): 7
- Term (months): 48
- Monthly payment ($) (for time to pay off): 500
| Monthly payment | $478.92 |
| Total interest | $2,988.39 |
Tips for better results
- If the payment is smaller than the monthly interest, the balance never shrinks, and the tool says so.
- Small increases in the payment can cut years off a long loan.
Common mistakes to avoid
- Choosing a payment that barely covers interest.
- Comparing loans with different fees as if they were the same.
Please note: Calculators and guides give general estimates, not financial, tax or investment advice. Real offers depend on your lender, location and personal situation. See our Disclaimer.