Calculator
Credit Card Interest Calculator
Calculate daily and monthly interest on your outstanding credit card balance.
Last updated 18 June 2026
How this works
Calculate daily and monthly interest on your outstanding credit card balance.
The calculator takes 3 inputs (outstanding, apr %, days in cycle) and produces 2 outputs (monthly interest, daily interest). All formulas are published below — no hidden assumptions, no sign-up wall, no data sent to a server.