Input parameters
- Loan Amount
- The principal amount borrowed before interest and fees.
- Loan Term
- The length of time allowed to repay the loan.
- Monthly Payment
- Known monthly principal-and-interest payment.
Interest Rate Calculator
Find the annual interest rate implied by a loan amount, loan term, and known monthly payment. The result is solved from the amortization equation and can be used to estimate total interest and balance reduction.
There was an error with your calculation.
Interest Rate
Interest Rate: 3.74%
Total of 120 Monthly Payments: $120,000.00
Total Interest Paid: $20,000.00
Interest
Principal
Balance
0 yr
5 yr
10 yr
Understanding the Interest Rate Calculator
Review the inputs, outputs, calculation method, and formulas used by this tool.
Understanding the results
- Interest rate
- Annual rate implied by the loan amount, term, and payment.
- Total interest
- Payment total above original principal.
- Balance progression
- Estimated amortization at the solved rate.
Calculation principle
Because the loan-payment equation cannot be rearranged simply for the rate, the calculator solves it numerically.
- Read and validate the entered values.
- Convert percentages and time periods into compatible units.
- Apply the formulas below and present the calculated results.
Formulas
Payment equation
M = P × r(1 + r)^n / ((1 + r)^n − 1)
Annual rate
Annual rate = solved monthly r × 12 × 100
Symbols refer to the corresponding input and result labels shown above.
How to use this calculator
Enter your figures, choose any available options, and select Calculate. You can change the inputs as often as you like to compare scenarios.
Planning note
Results are estimates for education and planning. Taxes, lender rules, fees, and investment returns can vary, so verify important decisions with a qualified professional.