What this calculator does
Find out whether moving your card balance would really save you money. Enter what you owe, your current APR and what you can pay each month. Then enter the new card's fee and intro offer. You'll see your savings after the fee, and how much you'd need to pay to clear it in time.
A balance transfer moves your debt to a new card with a low intro rate for a set time. It usually comes with a fee, which is added to your balance. The savings are often real, but the clock matters. Whatever is left when the intro period ends goes to the card's regular APR.
Where it's used
Why this math matters outside the classroom:
- Choosing an offer. A cardholder compares a 3% fee with 18 months at 0% against staying at 24.99% and saves about $2,592.
- Setting a target. A borrower splits $8,240 over 18 months to set a payment goal of about $457.78.
- Planning the leftover. A teacher paying $350 a month sees $1,940 left when the intro ends and plans for it.
- Classroom finance. Students build a monthly balance table on a spreadsheet to compare two payoff paths.
Grade level and standards: Grades 11–12; Common Core State Standards for Mathematics HSA.SSE.B.4. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter your balance, your current APR and the monthly payment you can manage.
- Enter the transfer fee, the intro APR and how many months it lasts.
- Enter the APR the new card charges after the intro period.
- Read your savings, then check the payment that clears the debt in time.
What the inputs mean
- Monthly payment you can make
- The same payment is used for both cards, so the comparison is fair. It's what you can really pay each month, not your minimum.
- Transfer fee
- Check the offer's terms. The fee is added to your new balance on the first day.
- New card APR after the intro
- The rate after the intro period. It's the APR the card's terms list as your regular rate.
Formula and method
fee = balance × fee % starting balance = balance + fee each month: interest = balance × APR ÷ 12; new balance = balance + interest − payment payment to clear in the intro = starting balance ÷ intro months (at 0%) savings = interest if you stay − interest if you transfer − fee
The calculator plays out both choices one month at a time. Each month it adds interest, then takes off your payment, until the balance reaches zero. It then adds up the interest for each path.
When the intro APR isn't 0%, the payment to clear it uses the standard loan formula instead of a simple split. That's because some interest is still charged during the intro period.
The savings figure counts the fee. A transfer can show a negative number if the fee or the later APR costs more than you'd save.
Worked example
You owe $8,000 at 24.99% and can pay $350 a month. A new card offers 0% for 18 months with a 3% fee, then 24.99%.
- Fee: $8,000 × 3% = $240.
- Starting balance: $8,000 + $240 = $8,240.
- Payment to clear it in the intro: $8,240 ÷ 18 ≈ $457.78 a month.
- Staying put: 32 months and about $2,975.11 of interest.
- Transferring at $350 a month: 18 × $350 = $6,300 paid, leaving $1,940 when the intro ends.
- That $1,940 takes 6 more months at 24.99%, with about $142.96 of interest.
- Savings: $2,975.11 − $142.96 − $240 ≈ $2,592.14.
Result: The transfer saves about $2,592.14 after the fee. Paying about $457.78 a month would clear it before the intro ends.
Understanding the result
Aim for the payment to clear it, if you can. In the example, adding about $107.78 a month means no interest at all.
If you can't reach that payment, a transfer can still help, as the example shows. Just plan for the balance left over.
The savings only hold if you stop adding to the debt. New spending isn't counted here. On many cards it can also lose the intro rate or cost extra interest, so read the terms.
Assumptions and limitations
- You move the full balance and make the same payment every month, on time.
- You make no new purchases on either card.
- Interest is charged monthly at APR ÷ 12. Real cards usually work it out daily, so statements can differ a little.
- Your payment arrives at the end of each month.
- It doesn't check whether you'd be approved, or what credit limit you'd get. A low limit may not fit your whole balance.
- It doesn't include annual fees, or the loss of a promo after a late payment.
- Rates and offers vary. Enter the terms you've actually been offered.
Frequently asked questions
Is a balance transfer worth the fee?
Usually, if you're paying a high APR and can clear most of the debt in the intro period. In the example, a $240 fee saves about $2,832 of interest. Run your own numbers to check.
What happens when the intro period ends?
Whatever is left starts being charged the card's regular APR. That's why this page shows the balance left at the end of the intro period.
How do I work out the monthly payment to clear it?
At 0%, add the fee to your balance and divide by the intro months. The calculator does this for you, and uses the loan formula if the intro APR isn't 0%.
Can a transfer cost more than staying put?
Yes. It can happen with a high fee, a short intro period, a low current APR or a high later APR. The savings figure turns negative when that happens.
How this calculator is checked
Method: Month-by-month balance simulation with interest at APR ÷ 12; fee added to the opening balance; standard level-payment formula for the clearing payment. Tests use a separate decimal simulation. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-31. Found a problem? Tell us.
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