Estimate APR from the money received and repaid
Enter the loan principal, stated annual interest rate, number of monthly payments and upfront finance charges. This calculator models a fixed-rate loan repaid in equal monthly installments, starting one month after the advance. It calculates the payment from the full principal and treats the entered fees as money paid or withheld at the start, reducing net proceeds.
The CFPB explains the difference between interest rate and APR: APR reflects financing costs beyond the stated rate. A lower payment or APR alone does not establish which loan is suitable; term, total cost and other conditions also matter.
Calculation and worked example
For principal P, monthly interest rate r and n payments, M = P × r / (1 − (1 + r)^−n). When the stated rate is zero, M = P / n. The calculator then finds the monthly rate i at which all payments have a present value equal to P − F, where F is the upfront finance charge. It reports 1,200 × i as the annual percentage rate. This is nominal annualization, not an effective annual yield.
For a principal of USD 10,000, a 6% annual rate, 60 payments and USD 500 in upfront fees, the unrounded monthly payment is approximately USD 193.328015. Net proceeds are USD 9,500. Discounting the 60 payments to those proceeds gives an estimated APR of 8.1543%, displayed as 8.15%. Total scheduled payments are approximately USD 11,599.68. Display rounding does not change the calculation.
Which fees belong in the input
Enter only upfront charges that are treated as finance charges for the comparison. Do not automatically enter every closing cost. Regulation Z's finance-charge rules contain inclusions and exclusions that depend on the transaction. This tool does not determine how a particular fee must be classified. Check the lender's itemized disclosure when deciding what to enter.
Assumptions and limits
The model follows regular monthly cash flows, consistent with the amount-and-timing principle in Regulation Z section 1026.22. It is an educational estimate, not a lender disclosure or a compliance calculation. The annual rate stays fixed, payments are unrounded internally and fees are not added to principal. There are no recurring charges, balloons, early repayments or odd-length first periods. It is not a credit-card or variable-rate APR model.
Use 1 to 1,200 whole monthly payments. Principal must be positive and upfront fees must be non-negative and smaller than principal. Extremely large amounts that cannot retain useful currency precision are rejected. A lender's dates, rounded payment schedule or included charges can produce a different disclosed APR.