Payment calculator
Work out the payment, the amount you can borrow, the term or the rate for any fixed-rate loan.
About the payment calculator
Work out the payment, the amount you can borrow, the term or the rate for any fixed-rate loan.
Part of SmartCalcy’s finance tools. It runs in your browser with no account, uses your own currency and units (change them at the top of the page), and gives estimates for information only, so check official guidance before you rely on a result.
How to use the payment calculator
What it calculates and when to use it
Solves a fixed-rate loan for whichever number is unknown: the payment, the amount you can borrow, the time to repay or the interest rate.
How to use it, step by step
- Choose what to work out.
- Fill in the other boxes.
- Read the answer and total interest.
What each input means
- Loan amount, Monthly payment, Rate, Term – Three of these four are needed; the fourth is the answer.
How to read the results
- The answer – Payment, borrowing power, time or rate.
- Total interest – Payments minus the amount borrowed.
The formula
Payment = P × r ÷ (1 − (1 + r)^−n). Borrowing = payment × (1 − (1 + r)^−n) ÷ r. Time n = −ln(1 − P × r ÷ payment) ÷ ln(1 + r). The rate is found numerically.
A worked example
20,000 at 6% over 5 years requires a payment of 386.66 and costs 3,199.36 in interest.
Assumptions and limits
- Fixed rate and equal monthly payments.
Common mistakes
- Entering a payment that is smaller than the monthly interest. The loan would never be repaid.
Frequently asked questions
What if the rate is zero?
The payment is the loan divided by the number of months.
Related tools
Details
- Total interest
- £3,199.36