Balance Transfer Calculator
Find out whether a 0% APR balance transfer offer actually saves you money once the transfer fee — and what happens if the balance isn't paid off in time — are factored in.
Your Balance & Transfer Offer
How balance transfer math actually works
A balance transfer moves debt from one card to another, usually to take advantage of a promotional 0% (or low) introductory APR. The catch is that most issuers charge a one-time transfer fee — typically 3% to 5% of the amount moved — which is added directly to your new balance the moment the transfer happens. That fee is the "cost of entry," and your promo-period interest savings need to outweigh it for the move to make sense.
The second, and more important, variable is time. If you don't pay off the transferred balance before the promotional window closes, whatever remains starts accruing interest at the card's standard "go-to" APR — often 20% or more. Some cards go further and use deferred interest, which retroactively charges you for interest on the entire original balance from day one if it isn't paid off in full by the deadline. Always read your specific offer's terms before transferring.
Months 1–N (promo): Interest = Principal × Promo APR ÷ 12
Months N+1 onward: Interest = Principal × Go-to APR ÷ 12
When a balance transfer makes sense
- You can realistically pay off the balance — or the vast majority of it — before the promo period ends.
- The fee is smaller than your projected interest savings. Run the numbers above before applying.
- You won't run up the old card again. A transfer only helps if you stop adding new charges to the balance you just moved.
- Your credit is strong enough to qualify for a card with a meaningful promotional window (12–21 months is common).
If your numbers show you won't pay off the balance in time, a fixed-rate consolidation loan may be a steadier alternative, since the rate won't jump partway through. And if you're deciding between a transfer and simply paying down your current card faster, check the Credit Card Payoff Calculator to see your payoff time at the current APR.
Frequently Asked Questions
Not always. A balance transfer only saves money if the interest you avoid during the promotional period is greater than the transfer fee, and if you can pay off (or make major progress on) the balance before the promo APR expires and reverts to the go-to rate.
Any remaining balance starts accruing interest at the card's standard go-to APR, which is often 20% or higher. Some cards also apply deferred interest, charging you retroactively for the entire promotional period if the balance isn't paid in full by the deadline — always check your card's specific terms.
Most balance transfer offers charge a fee of 3% to 5% of the transferred amount, either as a flat percentage or a minimum flat dollar fee, whichever is greater. This fee is usually added to your new balance immediately.
Opening a new card causes a small, temporary dip from the hard inquiry and a lower average account age. However, paying down revolving debt and lowering your credit utilization ratio can meaningfully improve your score over the following months.