The Finance Algorithm
§ Tool · tier 1 · independent

Credit Card Interest Calculator.

Calculate how much interest you're paying on your credit card balance

CalculatorFree, no signupOn-deviceupd May 2026
Inputs
Your numbers
$
$5k
%
20%

Purchase rate on your card (typical 18-22%)

$
$200

Amount you pay each month

$
$0

New purchases added monthly (extends payoff time)

Math updates live as you change inputs · AI runs on submit

Awaiting inputs

Move the sliders or type in the form on the left — the math updates live as you go. Click Get AI verdict when you want a written analysis.

Credit card interest compounds daily and adds up fast. This calculator shows you exactly how much you're paying in interest and how long it will take to become debt-free.

§ Worked examples

Real-world scenarios

$5,000 Balance at 20%

$5,000 balance at 20% APR, paying $200/month with no new purchases.

Inputs

balance:5,000rate:20payment:200

Time to payoff: 32 months. Total interest: $1,364. If you only paid minimum ($100): 9+ years and $5,840 interest!

§ FAQ

Questions Australians ask

§ Glossary

Plain-English definitions

Purchase Rate
The interest rate charged on purchases when you don't pay your balance in full.
Daily Interest
Credit card interest is calculated daily (rate ÷ 365) and compounds.
Minimum Payment
Usually 2-3% of balance or $25, whichever is higher. Designed to maximize interest paid.