Loan Calculator

How to use it

1. Enter principal, the nominal annual interest rate and the loan term.
2. Choose payment frequency and optionally add an extra amount per payment.
3. Review the scheduled payment, total interest and complete repayment schedule.

The method

For periodic rate r and n payments, payment = principal × r ÷ (1 − (1+r)^−n). Zero-interest loans divide principal equally across payments. Extra payments reduce the outstanding balance.

For example

A 12,000 loan at 0% for one year with monthly payments has a scheduled payment of 1,000.

A fixed rate and equal periods are assumed. Fees, taxes and lender-specific rounding are excluded. Weekly and biweekly schedules divide the nominal rate by 52 and 26.

Using Loan Calculator with the right inputs

Estimate monthly loan payments and total interest. Start by matching your task to the quantities and options shown below. The definitions of the inputs matter as much as the final number or transformed output; retain the original values so that you can repeat or check the result.

Inputs and options explained

• Loan amount: Enter the numeric value for this quantity using the units or scale shown in the label. The form indicates a minimum of 0.
• Annual interest rate (%): Enter the percentage in the scale shown by the label; for a field marked %, enter 5 for five percent rather than 0.05. The form indicates a minimum of 0.
• Term (years): Enter the numeric value for this quantity using the units or scale shown in the label. The form indicates a minimum of 0.
• Payment frequency: choose Monthly, Every two weeks, Weekly.
• Extra amount per payment: Use the amount for the period indicated and keep the currency consistent with other money inputs. The form indicates a minimum of 0.
• Start date: select a calendar date. Check the ordering of start and end values and any option controlling whether an endpoint is counted.

Method and interpretation

For a fixed-rate repayment loan, payment = P × r ÷ (1 − (1 + r)^−n), where P is the principal, r is the interest rate per payment period and n is the number of payments. When the rate is zero, principal is divided by the number of payments. Interest is calculated on the outstanding balance, so the principal and interest portions change over the schedule.

Worked example

Borrowing 12,000 at 0% for one year with monthly payments gives 12 payments of 1,000. This zero-rate example is useful for checking that the principal, term and payment frequency were entered as intended.

Assumptions and limitations

The nominal annual rate is divided by the selected number of payments per year. Fees, taxes, variable rates, payment holidays and lender-specific rounding are excluded. An APR that includes fees is not necessarily interchangeable with the nominal interest rate input. Compare the output with the lender's actual agreement before making a borrowing decision.

Before you use the output

• Choose the intended action: Calculate loan. Re-run the operation after changing an input or mode so that you are checking the updated result.
• Read the result label and any accompanying explanation. Keep the input values or source file with the output so that a later comparison uses the same assumptions.
• If a result looks unexpected, check units, separators and selected options first. Try a smaller example you can verify rather than repeatedly changing several settings at once.

Reference for further reading

CFPB: Understanding loan amortization. This reference explains the underlying topic; it does not certify this tool.

Questions or a result that needs checking?

If you find a discrepancy, report a problem with Loan Calculator. Include a non-sensitive example, the selected options, the result you expected and the result shown. This makes the issue easier to reproduce. See About & privacy for how the site handles tool inputs.