Is Credit Card Interest Compounded Daily?

What Is Compound Interest?

Compound interest is interest calculated on both the principal balance and any interest that has already accrued. In other words, you pay interest on your interest, which causes balances to grow faster over time.

Interest on debt can compound daily, monthly or annually. The more frequently it compounds, the faster a balance builds. For credit cards, daily compounding is the standard, which is why carrying a balance can get expensive quickly.

Be aware: Compounding isn't always a bad thing. When it applies to a savings account or an investment, more frequent compounding means you earn returns on your returns, accelerating growth over time. On a credit card, however, that same dynamic works against you.

Simple Interest vs. Compound Interest

The difference between simple and compound interest comes down to what the interest is calculated on.

With simple interest, you pay a fixed percentage of the principal balance each period and nothing more. With compound interest, each period's interest is added to the balance, and future interest is then calculated on that new, higher total.

On a credit card with daily compounding, this effect is even more pronounced. Interest accrues every single day, and your balance grows a little larger with each passing day you don't pay it off.

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How Often Does Credit Card Interest Compound?

In most cases, credit card interest is compounded daily using a daily interest rate and your account's average daily balance.

Your daily interest rate is derived from your card's annual percentage rate (APR). To find it, divide your APR by 365—though some card issuers use 360 instead. A card with a 20% APR, for example, carries a daily rate of roughly 0.055%.

That daily rate is applied to your average daily balance each day throughout your billing cycle. Your average daily balance is calculated by adding up your balance for each day in the statement period and dividing by the number of days in that period.

Each day's accrued interest is added to your balance, which becomes the starting point for the next day's calculation. Over the course of a month, these daily charges compound into the total interest charge that appears on your statement.

Be aware: For credit cards, APR and interest rate refer to the same thing. That's not always true for installment loans like mortgages or student loans, where the APR may also factor in origination fees and other costs.

How to Calculate Interest

Calculating your monthly interest charge takes a few steps, but the math is manageable:

1. Find your daily interest rate. Divide your APR by 365. For a card with a 20% APR, the daily rate is 20 / 365 = 0.0548%, or 0.000548 as a decimal.
2. Calculate your average daily balance. Add up your balances for each day in the billing cycle, then divide the total by the number of days in the cycle. If your balance was $800 for 15 days and $600 for the remaining 15 days of a 30-day cycle, your average daily balance would be [($800 x 15) + ($600 x 15)] / 30 = $700.
3. Multiply your average daily balance by your daily rate. Using the example above: $700 x 0.000548 = $0.3836 in interest per day.
4. Multiply by the number of days in the billing cycle. $0.3836 x 30 = $11.51 in interest for the month.

Keep in mind this is a simplified calculation. Actual charges can vary depending on whether you made purchases or payments during the cycle, which affect your daily balance.

Tip: You can also use Experian's credit card payoff calculator to better understand how interest can affect your balance over time.

How Do You Avoid Interest on Credit Cards?

The most effective strategies for avoiding credit card interest are straightforward, but they require consistency. Here's what you can do:

• Pay your full statement balance every month. Credit card issuers won't charge you for accrued interest if you pay your statement balance in full by the due date. Most cards include a grace period of at least 21 days between the end of your billing cycle and your payment due date. Be sure to stick to a budget to avoid spending more than you can afford to repay.
• Use a 0% intro APR card. Some credit cards offer an introductory 0% APR period during which no interest is charged on purchases, balance transfers or both. Just make sure to pay off the balance before the promotional period ends, which is when the card's standard variable APR takes effect.
• Transfer a balance to a 0% balance transfer card. If you're carrying a balance on a high-interest card, moving it to a card with a 0% introductory APR on balance transfers lets you pay down the principal without accumulating additional interest. Balance transfer cards typically charge a fee of 3% to 5% of the transferred amount.
• Avoid cash advances. Unlike purchases, cash advances typically start accruing interest immediately with no grace period, making them one of the fastest ways to accumulate interest charges. Using your card only for purchases keeps you within the grace period structure.
• Set up autopay for your full statement balance. Scheduling automatic payments for the full statement balance each month removes the risk of accidentally carrying a balance or missing a due date.

Frequently Asked Questions

The Bottom Line

Understanding how daily compounding works is the first step toward minimizing what you pay. Even a modest balance can grow faster than expected when interest is added every day, which is why paying your full statement balance each month is the most powerful tool in your arsenal.

If you're working to reduce existing credit card debt, Experian's free credit monitoring service can help you track your progress and spot opportunities to improve your credit and qualify for lower-rate cards over time.