Tested tool guide
Tested browser tools
Checked August 16, 2026
What APR Calculator does, with a checked example
A loan's advertised interest rate ignores origination fees, discount points, and closing costs charged to get that rate, so two offers with identical rates can cost differently. This calculator takes the loan amount, note rate, term, and total fees, computes the scheduled payment from the note rate, then solves for the discount rate that equates the present value of those payments to the amount actually disbursed after fees. That solved rate is the APR. The common surprise: on short-term loans a small fee inflates APR far more than the same fee does on a 30-year mortgage, because there are fewer payments to spread it across.
Worked example
A concrete input and expected output from the current implementation.
Input
Loan amount $10,000, note rate 6%, term 12 months, fee $100 deducted from proceeds
->
Expected output
Monthly payment: $860.66. APR: approximately 7.88%
The $860.66 payment is set by the $10,000 face amount at 6% over 12 months; solving for the rate that discounts those same 12 payments down to the $9,900 the borrower actually receives (after the $100 fee) yields about 7.88%, well above the 6% note rate because only 12 payments absorb the fee.