Credit Card Interest Calculator
Estimate approximate daily, monthly, and annual interest on a revolving credit card balance. This is an educational, simplified calculation — not an exact reproduction of your issuer’s statement math.
Inputs
Daily periodic rate
0.0630%
APR ÷ 365
Approximate daily interest
$3.15
On average balance $5,000.00
Approximate cycle interest
$94.48
30 days
Approximate monthly interest
$95.79
APR ÷ 12 method
Estimated annual interest
$1,149.50
If balance stays unchanged
Estimated ending balance
$5,094.48
Balance + charges − payment + interest
How this calculation works
- Daily periodic rate =
APR ÷ 365 ÷ 100. - Daily interest = average balance × daily rate.
- Cycle interest ≈ daily interest × days in cycle (no compounding).
- Average balance = starting balance + (new charges − payment) ÷ 2.
- Ending balance = starting balance + new charges − payment + cycle interest.
Important limitations
- Real issuers use the average-daily-balance method with daily compounding.
- Different balance categories (purchases, transfers, cash advances) may accrue at different rates.
- Grace periods, promotional APRs, and payment timing are not modeled.
- This is an educational estimate — your statement will differ.
Frequently asked questions
- What is APR?
- Annual Percentage Rate is the yearly interest rate a card charges on a revolving balance. It is disclosed on your statement and cardholder agreement.
- What is the daily periodic rate?
- Most U.S. issuers convert APR to a daily rate by dividing by 365 (or sometimes 360). The daily rate is applied to your balance to compute daily interest.
- What is a grace period?
- If you pay your statement balance in full by the due date, most cards do not charge interest on new purchases from that cycle. Carrying any balance usually eliminates the grace period until it is paid off.
- Why does my actual statement interest differ from this estimate?
- Real issuers usually use the average daily balance method with daily compounding, and treat purchases, payments, cash advances, and promotional balances separately. This calculator uses a simplified average.