The Finance Algorithm

Credit Card Interest Calculator

Calculate how much interest you're paying on your credit card balance

Updated October 2026Built and checked by MaverickHow it's calculatedReport an error

Your numbers

Updates as you type
$
$5k
%
21.24%

Purchase rate from your statement. RBA average: 21.24% standard cards, 13.49% low-rate cards

$
$200

Amount you pay each month

$
$0

New purchases added monthly (extends payoff time)

%
2%

From your statement. Used for the minimum-only comparison, with $20 as the floor

The button asks our AI to explain these figures in words.

Credit card interest

Time to pay off

34 mo

2.8 years

Total interest

$1,661

$6,661 total cost

Min-only path

Never

$26,576 interest

Saved vs min

$24,916

566 months faster

Interest cost at different monthly payments

Compare minimum-only to your current amount and small increases, even $50 extra has a big impact.

$26,576Minimum onlynever pays off$1,661Current34 mo at $200/mo$1,226+$5025 mo at $250/mo$977+$10020 mo at $300/mo$702+$20015 mo at $400/mo

Paying $200/month

Each payment chips away at the balance, but interest accrues daily, so the curve flattens early.

$0$1,250$2,500$3,750$5,000Mo 0Mo 7Mo 14Mo 20Mo 27Mo 34
Stop revolving. Credit card interest at 18-22% is one of the most expensive debt in the economy. Any spare cash earning <5% in a savings account is losing money compared to clearing the card. If you can't pay it off quickly, a balance transfer or personal loan at 8-10% usually wins.

How it works

Interest on a credit card balance adds up while the balance is unpaid. Enter your balance, rate and monthly payment to see how long it takes to clear the card, the interest you'd pay along the way, and how that compares with paying only the minimum.

  1. 1Enter your current credit card balance
  2. 2Add your card's purchase rate (check your statement)
  3. 3Input your monthly payment amount
  4. 4Optionally add ongoing monthly spending and your card's minimum repayment percentage
  5. 5See your interest cost and payoff time

The figures today

As of 7 November 2026, the lowest credit card purchase rate is 7.49%, from Unity Bank's Low Rate Visa Credit Card, while the typical best across 51 institutions is 12.49%.

Worked examples

$5,000 Balance at 20%

$5,000 balance at 20% a year, paying $200 a month with no new purchases. The card's minimum is 2% of the balance or $20.

Current balance
$5,000
Annual interest rate
20%
Monthly payment
$200
Monthly spending on card
$0
Minimum repayment (% of balance)
2%

Paid off in 33 months with $1,522 in interest. Paying only the minimum (about $102 to start, falling as the balance falls) would take 547 months, over 45 years, and cost $19,345 in interest.

Questions people ask

How is credit card interest calculated?
Interest is charged on the balance you haven't paid off, at the card's annual rate. Card terms set the method, and interest added to the balance then attracts interest itself. This calculator applies a twelfth of the annual rate each month.
Why does paying the minimum take so long?
Because the minimum is a small share of the balance, most of it goes on interest, and it shrinks as the balance shrinks. At 20% a year, a $5,000 balance paid at 2% of the balance (or $20 if more) takes over 45 years to clear.
Do I pay interest if I pay in full each month?
Not on purchases, if your card has interest-free days and you pay the full closing balance by the due date. Cash advances are usually charged interest from the day you take them.

The terms, in plain English

Purchase Rate
The interest rate charged on purchases when you don't pay your balance in full.
Interest-Free Days
Days on which purchases aren't charged interest, available only if you pay the full balance by the due date.
Minimum Repayment
The least you must pay each month, usually a percentage of the closing balance or a set dollar amount, whichever is more.

Official sources