Credit Card Interest Calculator
See what a credit card balance really costs. Enter your balance and APR to get the interest per day, per billing cycle, and per year.
Enter a balance and APR to see your interest cost.
What your result means
Credit card interest is charged only on a balance you carry past your due date. If you pay your statement balance in full each month, you generally will not be charged interest on purchases at all. When you do carry a balance, the cost adds up daily, and because most issuers compound daily, an unpaid balance grows a little faster each day it sits there.
How credit card interest is calculated
Three steps get you from an APR to a dollar figure:
- Find the daily periodic rate. Divide your APR by 365 (some issuers use 360). A 24.99% APR becomes about 0.06847% per day.
- Apply it to your balance. Multiply the daily rate by your balance to get one day of interest.
- Multiply by the days in your cycle. That gives the interest for the whole billing cycle.
Real issuers usually use the average daily balance method, which averages your balance across every day of the cycle before applying the rate. This calculator uses a simplified constant-balance version, so the number is close but not the exact figure on your statement. For a fuller walkthrough with examples, see the about page for how this tool works.
Worked example
Say you carry a $3,000 balance at 26.99% APR over a 30-day cycle:
- Daily periodic rate: 26.99% ÷ 365 = 0.07394% per day
- Interest per day: $3,000 × 0.0007394 = $2.22
- Interest for the cycle: $2.22 × 30 = about $66.55
That is why a "How much is 26.99% APR on $3,000?" question comes out to roughly $66 a month in interest alone, before you have paid down a cent of the balance.
Frequently asked questions
How is credit card interest calculated?
Issuers convert your APR into a daily periodic rate by dividing it by 365 (some use 360), then apply that rate to your balance each day of the billing cycle. This calculator uses a simplified constant-balance version: balance × daily periodic rate × days in the cycle.
Is credit card interest charged daily or monthly?
It accrues daily using the daily periodic rate, and most issuers compound it daily. The total then posts as a single finance charge on your monthly statement.
How much is 26.99% APR on a $3,000 balance?
The daily rate is 26.99% ÷ 365, about 0.07394% per day. On $3,000 that is roughly $2.22 a day, or about $66.55 over a 30-day cycle if the balance stays the same.
Is 20% APR high for a credit card?
It is close to the recent U.S. average. The Federal Reserve reported an average credit card APR of about 21% in the second quarter of 2026. A rate in the low twenties is typical; noticeably lower is good, and noticeably higher is expensive when you carry a balance.
How do I avoid paying credit card interest?
Pay your statement balance in full by the due date each month. Interest is charged only on balances carried past the due date, so paying in full within the grace period generally avoids interest on purchases.
Does this calculator match my statement exactly?
Not exactly. Real issuers use the average daily balance method with daily compounding, and your balance changes as you spend and pay. This tool gives a simplified constant-balance estimate, so treat it as a close approximation. If you want your real average daily balance from your actual purchases and payments, use the average daily balance calculator instead.
Disclaimer. This calculator is for educational and planning purposes only and is not financial advice. Actual interest depends on your card's terms, billing cycle length, and payment posting dates, and issuers commonly use the average daily balance method with daily compounding while this tool uses a simplified model. For decisions about debt, consult a qualified financial advisor or a nonprofit credit counselor.
Sources: daily periodic rate and calculation method confirmed against the Consumer Financial Protection Bureau, Citi, and Experian. Average APR figure (about 21%, Q2 2026) reported by the Federal Reserve via Forbes Advisor.