APR Calculation Methodologies & Truth in Lending Act (TILA) Compliance

The Truth in Lending Act (TILA), enacted in 1968 and implemented via Regulation Z, standardizes how lenders must disclose borrowing costs to consumers.

The Formula for Calculating APR

To convert a short-term finance charge into an annualized percentage rate:

APR = ( (Finance Charge / Principal) / Loan Term in Days ) * 365 * 100

For example, a $15 fee on a $100 loan for a 14-day term produces:

APR = ( ($15 / $100) / 14 ) * 365 * 100 = 391.07%

Nominal vs Effective Annual Rate (EAR)

While standard TILA APR represents a nominal annual rate without compounding, the Effective Annual Rate (EAR) accounts for compounding if a loan were rolled over 26 consecutive bi-weekly periods, demonstrating why avoiding rollover debt traps is mathematically imperative.