Average Daily Balance Calculator
See how your card issuer likely calculated this month’s interest.
Enter your starting balance, APR, and the purchases and payments from your billing cycle. We’ll estimate your average daily balance, show what drove it, and explain how timing changed your cost.
- Built around the average daily balance method many credit cards use
- Shows how purchases and payments changed your balance over time
- Explains what may lower your next finance charge
What this helps you understand
Why your interest charge may have felt higher than expected
Why an early purchase usually costs more than a late one
Why a payment made earlier in the cycle often helps more
How this calculator works
Your balance can change every day. Many card issuers look at each day’s balance during the billing cycle, add those daily balances together, and divide by the number of days to get your average daily balance. Then they apply your daily interest rate to estimate the charge.
Estimated interest = Average daily balance × Daily periodic rate × Billing-cycle days
For example, if you carried a higher balance for most of the month and only made a payment near the end, your average daily balance would stay relatively high — even if the ending balance looks fine.
FAQ
This is an estimate. Card issuers may apply transactions, posting timing, grace periods, fees, and interest categories differently. Use this tool as a planning and explanation aid, not as a replacement for your official statement. Cash advances, penalty APRs, and promotional balances are not modeled here.