Free tool

Credit card interest calculator

Enter your balance, the card's APR and what you pay each month. The sheet works out the interest and how long the balance lasts, with the same financial functions a spreadsheet uses.

fx=B2*B7
AB
1Your card
2Balance
3APR (%)
4Monthly payment
5
6Results
7Monthly interest rate1.83%
8Interest this month91.67
9Months to pay it off33.7
10Total interest (about)1,749.54
11Payment to clear it in 12 months467.97

Blue cells are inputs: type a new value and the sheet recomputes. Click a result to see its formula.

The formulas

How it works, step by step

=B3/100/12
The monthly rate. Cards quote a yearly rate (APR) but charge interest monthly, so divide by 12: 22% a year is about 1.83% a month. Most issuers actually charge a daily rate (APR / 365) on the average daily balance, which lands very close to this.
=B2*B7
Interest this month. The balance times the monthly rate: 5,000 × 1.83% = 91.67. That part of your payment goes to the bank; only the rest reduces the balance.
=NPER(B7,-B4,B2)
Months to pay it off. NPER returns the number of payments needed to bring a balance to zero at a fixed rate. The payment is negative because it is money going out. If the payment is not more than the monthly interest, the balance never goes down and NPER returns an error.
=PMT(B7,12,-B2)
The payment for a deadline. PMT turns the question around: the fixed payment that clears the balance in 12 months. Change 12 to 24 or 36 to compare plans.

Functions used here

NPERNumber of periods of an investmentPMTPeriodic payment of a loan or annuityIPMTInterest part of a paymentCUMIPMTInterest paid between two periods

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FAQ

Questions

How is credit card interest calculated?

The issuer divides the APR into a daily or monthly rate and charges it on the balance you carry. At 22% APR the monthly rate is about 1.83%, so a 5,000 balance costs about 91.67 in interest for the month.

How long will it take to pay off my credit card?

Use NPER with the monthly rate, your payment and the balance. 5,000 at 22% APR with 200 a month takes about 34 months, and about 1,750 of what you pay is interest.

Why does my balance barely go down?

Early on, a large part of each payment is interest. With 200 a month on 5,000 at 22%, about 92 of the first payment is interest and only about 108 reduces the balance.

What if my payment is lower than the interest?

Then the balance never goes down: interest adds at least as much as you pay. The calculator shows an error for the payoff months in that case. Raise the payment above the monthly interest.

Is this exact?

It is a close estimate. Real statements use a daily rate, the dates of your purchases and payments, and fees. New purchases on the card also add to the balance.

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