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The interest you pay on your credit card is calculated based on the APR of the account and your account balance. But the balance your card issuer uses in the interest calculation isn't the balance shown on your statement. Instead, it's the average daily balance for the billing period.
The credit card issuer calculates the average daily balance by taking your balance on each day in the period, adding them together, then dividing by the number of days in the period. The issuer has computers to do this, but you could if you wanted to figure it out by hand.
The more often you use your credit card, the more challenging it can be to keep track of your exact daily balance, let alone the average daily balance. That's why we've devised the following average daily balance calculator.
Start by entering the balance on the first day of your billing period and selecting the date of that first day. Then, enter any purchases or payments made for each day in the billing period. The calculator will track your daily balances and show you the average daily balance for the period.