Credit Card Interest Calculator

Last Updated:

See exactly how much interest your credit card balance is costing you per day, month, and year.

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Monthly Interest Charge

$0

Daily Interest$0
Annual Interest$0
Daily Periodic Rate0%

📐 Formula

Monthly Interest = Balance × (APR ÷ 12). Daily Interest = Balance × (APR ÷ 365). Daily Periodic Rate = APR ÷ 365

How to Use the Credit Card Interest Calculator

1

Enter your current balance

Input the outstanding balance shown on your statement. This is the amount on which interest accrues — not your credit limit.

2

Enter your APR

Input your card's Annual Percentage Rate from your statement or account portal. Average US card APR currently runs 20–24%.

3

Enter your monthly payment

Input your actual payment, not just the minimum. The calculator shows the dramatic difference in total interest between minimum payments and higher amounts.

4

Review total interest and timeline

These two numbers — total interest paid and months to payoff — are the true cost of carrying credit card debt.

How Credit Card Interest Is Calculated Daily

Credit card issuers use the Average Daily Balance method. Your APR is divided by 365 to calculate a daily periodic rate. This rate applies to your average outstanding balance each day of the billing cycle. For a card with 22% APR and a $3,000 balance: daily rate = 0.0603%, daily interest = $1.81, monthly charge ≈ $54. This calculation applies from the day a purchase posts if you carry a balance — there is no grace period on existing debt.

The Minimum Payment Trap

A card requiring 2% of balance as minimum payment on a $5,000 balance at 22% APR takes over 30 years to pay off at minimums-only — paying nearly $8,000 in interest on a $5,000 balance. Tripling the minimum to 6% of balance pays it off in under 4 years and costs approximately $1,200 in interest — a $6,800 saving. Minimum payments are designed to maximise issuer profit, not borrower outcomes. The calculator makes this visible: the gap between minimum and realistic payment is one of the most impactful numbers in personal finance.

How to Calculate Credit Card Interest by Hand: Worked Example

Card issuers charge interest daily, and you can reproduce the math on a receipt. Take a $5,000 balance at a 24.99% APR.

Step 1 — find the daily periodic rate (DPR). Divide the APR by 365: 0.2499 ÷ 365 = 0.00068466, about 0.068% per day.

Step 2 — compute one day's interest. $5,000 × 0.00068466 = $3.42 per day. That is what the balance costs you every single day it remains unpaid, including weekends.

Step 3 — extend across the billing cycle. Over a 30-day cycle: $5,000 × 0.00068466 × 30 = $102.70 of interest — before you have bought anything new. In practice issuers use your average daily balance, so mid-cycle payments shrink the base the daily rate applies to, which is why paying two weeks early genuinely costs less than paying on the due date.

Why did interest appear even though you paid the statement balance?

This is trailing or "residual" interest. If you carried a balance last cycle, interest kept accruing daily between the statement date and the day your payment arrived. The cure is to pay the current payoff amount (available from the issuer), not the statement balance, and then keep the card paid in full so the grace period is restored.

How Do You Stop a Balance From Growing? Three Levers, Ranked

Does paying twice a month actually reduce interest?

Yes, mechanically. Because interest is computed on the average daily balance, a $250 payment on day 1 and $250 on day 15 produces a lower average balance than a single $500 payment on day 28 — same cash, less interest. On the $5,000 example above, splitting payments typically saves a few dollars per cycle; small, but it compounds in your favor month after month.

Is a 0% balance transfer worth the fee?

Run the comparison with real numbers. Staying at 24.99% on $5,000 costs about $102 per month in interest. A transfer with a 3% fee costs $150 once. The fee pays for itself in under seven weeks, and every month of the promotional period after that is pure principal reduction — provided you make the payments that clear the balance before the promo rate expires.

Can you just ask for a lower APR?

Issuers grant rate reductions more often than most cardholders expect, particularly for accounts with on-time payment history. Even a cut from 24.99% to 19.99% reduces the daily cost on $5,000 from $3.42 to $2.74 — roughly $250 saved per year for a five-minute phone call.

Frequently Asked Questions

Credit card interest accrues daily using the Daily Periodic Rate (DPR = APR ÷ 365). Each day, interest is added to your average daily balance. This is why carrying a balance from month to month is so costly.
APRs below 15% are good. Most rewards cards range from 19–28% APR. If you pay your balance in full each month, the APR doesn't matter — you pay zero interest. The APR only applies to carried balances.
Pay your statement balance in full by the due date every month. Most cards have a grace period (21–25 days) where no interest accrues if you pay in full. Partial payments result in interest on the entire balance.
Daily Periodic Rate (DPR) = APR ÷ 365. On a 24% APR card: DPR = 0.0658%/day. If you carry a $5,000 balance, daily interest = $5,000 × 0.000658 = $3.29/day or about $99/month. Interest compounds daily on most US cards — which is why carrying a balance is extremely expensive at typical APRs.
The average credit card APR in the US reached historic highs in 2024–2025, hovering around 21–22% for existing accounts and 24–27% for new offers. Store cards often exceed 28–32% APR. The Fed's rate cuts in 2024–2025 only partially passed through to credit card rates.

Sources & Methodology

Calculations are based on the most current publicly available data from authoritative government and industry sources: