How does the calculator model a promotional transfer?
It starts by adding the transfer fee to the balance, since that is how issuers charge it. For each month inside the promotional period, it charges interest at the promo rate, which is zero on most offers, and subtracts your fixed payment. At 0%, the full payment reduces the balance.
When the promo months run out, the calculator records the remaining balance, then switches to the regular APR divided by 12 for every month after that. It keeps applying your payment until the balance is gone. Total interest covers both phases, and total cost adds the fee.
If the promo rate is not zero, say a reduced rate rather than 0%, the same approach applies with that rate during the intro months. The key output is the balance when the promo ends: zero means the plan clears the debt in time; anything above zero is the amount that will be exposed to the higher rate.
Starting balance = Balance × (1 + fee %) Payment to clear by promo end (0%) = Starting balance ÷ promo months After promo: interest = Remaining balance × (regular APR ÷ 12)
- fee %
- one-time transfer fee rate
- promo months
- length of the introductory rate period
- regular APR
- ongoing rate applied after the promotion ends
Example: $9,200 on a 15-month 0% offer
Scenario: You move $9,200 to a card offering 0% for 15 months with a 4% fee. After the promotion the rate becomes 26.99%. You plan to pay $500 a month and make no new purchases on the card.
- Fee and starting balance$9,200 × 4% = $368.00; starting balance $9,568.00
- Promo phase15 payments of $500 at 0% reduce the balance by $7,500.00
- Balance when promo ends$9,568.00 − $7,500.00 = $2,068.00
- First month at the regular rate$2,068.00 × 26.99% ÷ 12 = $46.51 of interest
- Payoff and costPayoff takes 20 months in total; interest $128.24 + fee $368.00 = $496.24
- Payment that beats the deadline$9,568.00 ÷ 15 = about $637.87 a month, which leaves nothing for the 26.99% rate to touch
At $500 a month you owe $2,068.00 when the promo ends and pay $496.24 in total cost; raising the payment to about $637.87 cuts the cost to just the $368.00 fee.
For comparison, paying $500 a month on the original 26.99% card would take 25 months and cost $2,808.04 in interest.
When is a promo-rate transfer worth modeling?
Before accepting a 0% offer
Check whether the payment you can afford clears the balance before the deadline. If it does not, you know in advance how much will roll into the regular rate.
Comparing offers with different lengths and fees
A longer promo with a higher fee may suit a larger balance; a shorter promo with a lower fee may be cheaper if you can pay aggressively. Run each one with your real payment.
Partway through a promotion
Enter your current balance and the months left as a fresh scenario, with the fee set to zero since it is already paid. You will see whether you are on pace or need to raise the payment.
Planning a second transfer
If a balance will remain at the deadline, some people plan another transfer. Modeling it shows whether a second fee is cheaper than the regular rate on what remains.
What mistakes turn a 0% offer into an expensive one?
Paying only the minimum during the promo
Minimums on a 0% balance are small, which feels comfortable but leaves most of the balance in place when the regular rate arrives. Set your own payment based on the deadline instead.
Missing a payment
A late payment can bring a fee and, depending on the agreement and how late it is, can cost you the promotional rate. Automating at least the minimum and paying extra by hand protects the offer.
Running the old card back up
Clearing the old card frees its credit line. Spending on it again means you carry the transferred balance and a new balance, which can leave you deeper in debt than before.
Confusing 0% intro APR with deferred interest
Some store and retail financing offers defer interest: if the full balance is not paid by the deadline, interest is charged back to the start. A true 0% intro APR does not do that. Read which kind your offer is.
Buying on the transfer card
New purchases may carry a regular purchase rate and, while a balance is carried, may accrue interest immediately. Use a different card or cash for spending during the promotion.
How does your payment change what you owe at the deadline?
During a 0% promotion, the arithmetic is linear: every dollar of payment removes a dollar of balance. That makes it easy to aim for zero. After the deadline, the regular APR turns any remaining balance back into a compounding problem.
The table runs the same $9,568 starting balance through five payment levels. At $300 a month, $5,068.00 is still owed when the promotion ends, and the interest that follows is more than three times the fee. At about $637.87 or more, the regular rate never applies.
| Monthly payment | Balance when promo ends | Payoff time | Interest | Total cost (fee + interest) |
|---|---|---|---|---|
| $300.00 | $5,068.00 | 37 months | $1,379.56 | $1,747.56 |
| $400.00 | $3,568.00 | 26 months | $459.30 | $827.30 |
| $500.00 | $2,068.00 | 20 months | $128.24 | $496.24 |
| $637.87 | $0.00 | 15 months | $0.00 | $368.00 |
| $700.00 | $0.00 | 14 months | $0.00 | $368.00 |
What protections apply to promotional rates?
Federal card rules set some guardrails. A promotional rate generally must last at least six months, and the terms must disclose the rate that will apply afterward. When you pay more than the minimum, the excess generally goes to the balance with the highest rate first, which helps if you also carry purchases at a higher APR.
The rules do not stop a promotion from ending on schedule, and a payment more than 60 days late can allow the issuer to apply a higher rate to existing balances. Your agreement spells out exactly what can end the promotion early. The safest plan is a payment large enough to clear the balance in time, made on time every month.
Terms used on this page
- Promotional APR
- A promotional APR is a temporary, reduced interest rate, often 0%, that a card issuer offers for a set period on purchases, balance transfers or both. When the promotion ends, any remaining balance is charged the card's regular APR. It can save real money if you plan to pay the balance off within the window.
- Balance Transfer Fee
- A balance transfer fee is a one-time charge for moving debt onto a credit card, usually a percentage of the amount transferred, often with a dollar minimum. The fee is added to your new balance right away, so it is the upfront price of a lower promotional rate and must be weighed against the interest you save.
- Balance Transfer
- A balance transfer moves debt from one credit card or loan to another card, usually to take advantage of a low or 0% promotional APR. It can cut interest sharply while you pay down the balance, but most transfers carry a fee, and any amount left when the promotion ends is charged the regular rate.
- APR (Annual Percentage Rate)
- APR is the yearly cost of borrowing expressed as a single percentage that includes the interest rate plus certain required fees, such as origination charges. Because lenders must calculate it the same way under federal Truth in Lending rules, APR lets you compare loan offers on an even footing.
- Minimum Payment
- The minimum payment is the smallest amount a credit card issuer or lender requires each billing cycle to keep the account in good standing. On cards it is often a small percentage of the balance plus interest, so paying only the minimum keeps you current but can stretch repayment over many years and multiply interest.
0% Balance Transfer Calculator: common questions
What happens when a 0% balance transfer ends?
Any balance still on the card starts accruing interest at the regular APR from that point. Interest is not charged retroactively on a true 0% intro APR. Your payment and minimum may rise as interest is added, so checking the balance a few months before the deadline gives time to adjust.
Is the transfer fee worth paying for 0% APR?
Usually, if you clear most of the balance during the promotion. The fee is a one-time cost, while high-rate interest continues every month. In the example, the $368.00 fee compares with $2,808.04 of interest at 26.99% on the same payment. If you can pay the balance off in a few months anyway, the fee may not be worth it.
How is deferred interest different from a 0% intro APR?
With deferred interest, interest accrues in the background from day one and is charged in full if any balance remains at the deadline. With a 0% intro APR, no interest accrues during the promotion and only the leftover balance is charged the regular rate going forward. Deferred interest is common on store financing.
Can I do another balance transfer when the promo ends?
Possibly, if you qualify for a new offer. You would pay another transfer fee, and a new application can affect your credit. Compare that fee with the interest the remaining balance would cost at the regular rate. Planning to clear the balance the first time is more reliable. Approval for a new card is never guaranteed, especially if your utilization is still high, so it is risky to build a plan that depends on it.
Does paying late cancel a 0% promotional rate?
It can, depending on the agreement and how late the payment is. Federal rules allow an issuer to raise the rate on existing balances once a payment is more than 60 days past due, and even one late payment can bring a fee. The card agreement lists what can end the promotion. Autopay for at least the minimum is the simplest safeguard.
Why is my minimum payment so low on a 0% transfer?
Minimums are usually based on a small percentage of the balance plus interest, and with no interest the minimum is small. Paying only that leaves most of the balance at the deadline. Set your payment using the balance plus fee divided by the promo months instead. The calculator above shows how much would remain at the deadline if you paid less than that amount.
Should I use the 0% card for new purchases?
It is usually better not to, unless the offer also includes a 0% purchase rate and you plan to pay those purchases off within the promotion too. Mixed balances at different rates make the payoff harder to track and can bring interest on purchases. Using a separate card for spending, and paying it in full each month, keeps the transfer balance shrinking on schedule.
What if I can't afford the payment that clears the balance in time?
Pay as much as you can and plan for the remainder. The calculator shows the balance at the deadline, so you know how much will face the regular rate. Directing any windfalls to the card before the deadline, or trimming other spending for those months, can close the gap. Running the calculator a few months before the deadline shows exactly how large the leftover balance will be.
Does the regular APR after the promo stay fixed?
Usually not. Most regular card APRs are variable and move with a benchmark rate, so the rate when the promo ends may differ from the one disclosed when you applied. Use a slightly higher rate in the calculator to see how sensitive your plan is. Issuers generally must give advance written notice before raising the rate on an account, which gives you time to adjust your plan.
Sources
- Regulation Z (Truth in Lending), 12 CFR Part 1026 — Consumer Financial Protection Bureau. Accessed October 17, 2026.
- Credit cards — Consumer Financial Protection Bureau. Accessed October 17, 2026.
- Credit reports and scores — Consumer Financial Protection Bureau. Accessed October 17, 2026.
We cite primary sources: regulators, central-bank data and federal agencies. Worked examples on this page are our own calculations, last checked October 17, 2026. See our methodology.