APR as a comparison language
Annual percentage rate exists so borrowers can compare offers that hide costs in different places. A lower sticker interest rate can still be expensive once fees are annualized. This APR calculator is a small model for intuition—helpful before you open five lender tabs—not a statutory disclosure generator.
How to think about inputs
Start with the amount borrowed, the rate you were quoted, and any upfront finance fees you can identify. Compare total interest and payment feel next to a plain loan calculator. For revolving cards, payoff behaviour often matters more than the headline APR alone.
US and UK labelling
US consumer loans often emphasise APR under federal advertising rules; UK regulated credit leans on representative APR and total cost of credit. Packaging differs; the need to read fees carefully does not. Treat outputs as estimates for learning and planning only.