Finance Charge Calculator
Calculate the finance charge on a credit card or loan using the average daily balance method, showing how much interest accrues over a billing cycle.
How to use this tool
- Enter average daily balance, annual percentage rate (apr) and billing cycle length in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your finance charge and the full breakdown beneath it.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Daily Periodic Rate = APR / 365
Finance Charge = Average Daily Balance × Daily Periodic Rate × Billing Days
= ADB × (APR / 365) × Days
How it works
Most credit card issuers use the average daily balance method: the outstanding balance is recorded each day, summed, and divided by the number of days in the billing cycle to compute the average daily balance. The finance charge equals this average multiplied by the daily periodic rate (APR ÷ 365) and the number of days. This is the method required to be disclosed under the Truth in Lending Act (TILA).
Worked example
$2,000 Balance at 18% APR over 30 Days
- Average daily balance = $2,000; APR = 18%; billing cycle = 30 days.
- Daily periodic rate = 18% / 365 = 0.049315% per day.
- Finance charge = $2,000 × (0.18 / 365) × 30 = $2,000 × 0.000493151 × 30.
- Finance charge = $2,000 × 0.014795 = $29.59.
Finance charge is $29.59 for the 30-day billing cycle.
Common mistakes to avoid
- Using the statement balance instead of the average daily balance — finance charges on most credit cards are calculated on the average of daily balances throughout the billing cycle, not the closing balance.
- Dividing the APR by 12 (monthly rate) instead of 365 (daily periodic rate) for a daily-balance method card, which understates the finance charge.
- Forgetting that paying the full statement balance by the due date avoids the finance charge entirely — this calculation applies only when a balance is carried from the previous cycle.
Key terms
- What is a finance charge?
- A finance charge is the total dollar amount paid to borrow money, including interest and any applicable fees, expressed as a cost of the billing period.
- What is the average daily balance method?
- The issuer tracks your balance each day, sums the daily balances, divides by the number of days in the cycle to get the average, then multiplies by the daily rate.
- How can I avoid finance charges?
- Pay your full statement balance by the due date each month; most credit cards offer a grace period during which no interest is charged on new purchases.
- What is APR vs. interest rate?
- APR (Annual Percentage Rate) includes interest plus certain fees and is the standardized rate used in TILA disclosures; the nominal interest rate may be lower.
Frequently asked questions
- How does the average daily balance method work?
- The card issuer sums the ending balance for each day in the billing cycle and divides by the number of days. Purchases and payments shift the daily balance, affecting the average and therefore the finance charge.
- What happens to the finance charge if I make a payment mid-cycle?
- A mid-cycle payment reduces the average daily balance from the payment date forward, lowering the finance charge for that billing period proportionally.
- Is the finance charge the same as APR?
- No. APR is an annualized rate. The finance charge is the actual dollar amount of interest charged for a specific billing period, derived by applying the daily periodic rate to the average daily balance over the billing days.