Finance Charge Calculator

What this calculator does

When you carry a balance on a credit card, it costs you money. The finance charge is that cost, put as a figure you could hand over: the actual amount the borrowing adds up to over a period. This calculator works it out. You enter the balance you owe and the card's rate, and it tells you the finance charge, and what your balance grows to once the charge is added on.

It can do this for a single billing cycle or for any stretch of days you choose, whether you type the number of days or pick two dates. Either way, the thing it is measuring is the same: the price, in money, of not paying the balance off yet.

A finance charge is an amount of money, not a rate

This is the distinction that makes everything else click. People tend to blur the finance charge together with the APR, but they are different kinds of thing. The APR is a rate, a percentage, the speed at which interest builds. The finance charge is a sum of money, the distance you actually travelled at that speed over a given time.

An APR of 22 percent tells you nothing on its own about what you will pay. Pay for what balance, over how many days? Only once you attach a balance and a length of time does the rate turn into a real, spendable figure, and that figure is the finance charge. This is not just a casual definition, either. In lending law the finance charge is a formal term: the cost of credit expressed as a dollar amount, which is meant to capture what borrowing truly costs you rather than hide it inside a percentage. So when you compare the APR and the finance charge, you are comparing a speed with a distance. This tool converts the one into the other.

How to use it

1. Current balance owed. The balance the charge will be calculated on.
2. APR. The card's annual percentage rate, as a percent.
3. Calculate for. Choose a billing cycle, and give its length in days, or choose a given term, where you either set a number of days, weeks, or months, or pick a first and last date and let the calculator count the days between them.

Press Calculate. For a billing cycle it returns the finance charge and your new opening balance for the next cycle. For a given term it returns the charge for the period you chose. Press Reset to clear the fields.

How a yearly rate turns into a daily bite

Credit card interest is quoted by the year but charged by the day, and that is the key to how the finance charge is built. The calculator takes the APR and divides it by 365 to get the daily periodic rate, the small slice of interest that applies for a single day:

Daily periodic rate = APR ÷ 365

Then it charges that daily rate on your balance for every day in the period. So the finance charge is simply your balance, times the daily rate, times the number of days you carried it:

Finance charge = Balance × (APR ÷ 365) × Days

Two things fall out of this. First, days are the real currency here: the longer you carry a balance, the more days of interest stack up, which is why paying sooner rather than later genuinely costs less. Second, for a billing cycle the calculator adds the finance charge to your balance to give next cycle's opening figure, and that is interest quietly being charged on top of interest, since the following cycle's charge is worked out on the higher balance.

A worked example you can check

Say you owe 2,000, your card's APR is 22 percent, and the billing cycle is 30 days. Let us run it.

• Daily periodic rate: 22 ÷ 365 = 0.06027 percent a day
• Finance charge: 2,000 × 0.0006027 × 30 = 36.16
• New opening balance: 2,000 + 36.16 = 2,036.16

So carrying that 2,000 for one 30-day cycle costs about 36. Modest for a month, but notice the new balance: next cycle's interest is charged on 2,036.16, not 2,000. Leave it running month after month, paying little or nothing, and each cycle's charge is slightly larger than the last. That is the quiet arithmetic that makes a lingering balance so expensive over time.

The way to owe nothing: the grace period

Here is the part that can save you the entire charge, so it is the most useful thing on this page. Most credit cards give you a grace period, a window between the end of your billing cycle and your payment due date. Pay your statement balance in full within that window, and you are charged no interest at all on your purchases. The finance charge this calculator shows you simply does not apply.

The catch is what happens when you do not. If you carry a balance past the due date rather than clearing it, you lose the grace period, and interest starts applying, not only to the old balance but often to new purchases straight away, with no interest-free window at all until you are paid up again. That is the difference this tool is really illustrating. The finance charge is what a carried balance costs, and the grace period is the escape hatch that lets you avoid it entirely by paying in full. If you can clear the statement each month, the number here stays hypothetical, which is exactly where you want it.

One thing real card statements do differently

This calculator charges the rate on the balance you enter, held steady across the days. It is a clear and close way to see what a carried balance costs, and it is worth knowing that a real card statement usually adds one more wrinkle. Most issuers apply the daily rate to your average daily balance, the average of what you owed on each day of the cycle, rather than a single fixed figure.

The reason they do it is that your balance moves during a month, as purchases and payments land on different days. Averaging those daily balances means a payment made early in the cycle lowers the average, and so lowers the charge, while a big purchase early in the cycle raises it. So treat the figure here as an accurate estimate for a steady balance, and as a very good guide to the mechanics, while remembering that your statement fine-tunes it day by day. The core lesson does not change: the rate, the balance, and above all the number of days are what drive the cost.

Questions people ask

What is the difference between the finance charge and the APR?

The APR is a rate, a yearly percentage. The finance charge is an amount of money, what that rate actually costs on a given balance over a given number of days. The tool turns the rate into the charge.

How do I avoid a finance charge altogether?

Pay your statement balance in full by the due date, within the grace period most cards offer. Do that and no interest is charged on your purchases. Carry a balance past the due date and you lose that window.

Why divide the APR by 365?

Because interest is charged daily. Dividing the yearly rate by 365 gives the daily periodic rate, the amount applied for each day you carry the balance. Some issuers use 360 instead, but 365 is the common choice.

Why is my new balance higher than what I owed?

Because the finance charge is added to the balance. Next cycle's interest is then calculated on that larger figure, which is how interest ends up being charged on interest when a balance lingers.

References

The daily periodic rate, defined as the APR divided by 365 (or in some cases 360) and applied to the balance each day so that interest compounds daily, and the grace period, within which paying the balance in full avoids interest, both follow the US Consumer Financial Protection Bureau.

1. U.S. Consumer Financial Protection Bureau, What is a "daily periodic rate" on a credit card? https://www.consumerfinance.gov/ask-cfpb/what-is-a-daily-periodic-rate-on-a-credit-card-en-46/
2. U.S. Consumer Financial Protection Bureau, What is a grace period for a credit card? https://www.consumerfinance.gov/ask-cfpb/what-is-a-grace-period-for-a-credit-card-en-47/