About the Balance Transfer Calculator
A 0% APR balance transfer advertises 12–24 months of interest-free payments — for a one-time transfer fee of around 3–5% of the balance. Both parts of that comparison matter: the promo interest saved, and the fee that caps the theoretical savings.
This tool models both timelines. The old path: current APR compounding on the balance at your payment. The new path: fee charged up front, no promo interest, then the standard APR applies once the promo ends. It reports months-to-payoff, total cost, and the savings.
The formula behind it
Two payoff simulations, same payment, different rate paths:
Old: am=curAPR from month 1 • New: promo APR for N months, then current APR; fee = balance × fee% added at startPromo interest saved (old plan interest − new plan interest minus fee). Payoff dates and total costs compare both the paths. If new plan isn’t paid off by promo end, the difference is the waived promo interest alone (or forgiven wait until the standard APR applies).
Worked example
Defaults — $8,000 at 21% APR, paying $250/month, 18-month 0% promo with a 3% fee:
- Old plan: interest total about $3,831; payoff at month 48.
- New plan: transfer fee $240, promo interest $0, then the remaining balance clears at 21% — total interest+fee ≈ $875.
Takeaway: Savings ≈ $3,200 — the $240 transfer fee is about 7% of the saving. Had the promo been 12 months instead, the remaining balance would attract promo-end interest and the savings would shrink — the exact trade-off the tool details on a per-month basis.
What moves the result
- Transfer fee — a 3–5% fee is the cost of entry that charges against all of the saving; fee-free offers are rare and priced accordingly.
- Payment discipline — doubling your monthly payment accelerates both timelines; the low interest dominates the promo period.
- Promo length — the amount the promo ends before payoff of the transferred balance can leave remaining high-APR balances to carry at the promo-end rate.
- Where the promo applies — a 0% balance-promo promo sometimes applies only to the transferred portion, not to new purchases inside your line.
Practical tips
- Do not add new charges to either card — the promo often covers the transfer only, and you can undo the savings that way.
- Do not miss a payment during the promo; one late payment can void the 0% offer and the rate you never see.
- Plan to pay off the transferred balance before the promo ends; the tool plots it.
- Run the same numbers if you can qualify for a personal-installement or 0%-promo-extended-card instead — each has different fee/promo trade-off conditions.
- For a thorough equilibrium view, the debt-consolidation calculator shows a loan-structured comparison against continuing your cards.
Frequently asked questions
Is the fee worth it?
Almost always on high-APR card balances: a 3% fee on $8,000 is $240, replacing a year+ of interest at $100+ per month. Where it gets close to break-even is when the calendar disagreement, the promo is short, and the amount is small.
What if I can’t finish paying the balance by the promo end?
The remaining balance then attracts the standard rate. The tool models that rate exactly like a normal card: the savings are sized against the time the promo covers.
Do balance transfers affect your credit score?
Usually a positive effect over time: a lower utilization rate, plus no credit pull in many cases. The initial inquiry impact is typically small for most people.