Cash Back or Low Interest Calculator

Compare a cash back offer vs a low APR offer for the same spending and payoff plan. See the break-even point and which option costs less.

How to Use

  1. Enter your purchase amount (or expected spend).
  2. Enter the cash back rate and any sign-up bonus (optional).
  3. Enter the APR for the low-interest option and your payoff plan.
  4. View the winner, estimated interest cost, cash back value, and break-even spend.

Note: This tool estimates interest using a simple monthly balance approximation (fast + deterministic). Your issuer’s exact daily-compounding method can differ slightly.

Inputs
All amounts in USD. APR is annual percentage rate.
If you’re comparing promos for a specific purchase, use that total.
Used to estimate average balance and interest cost.
Example: 2% cash back on all purchases.
If you’ll definitely qualify. Leave blank if not sure.
APR used for estimated interest if you carry the balance while paying it off.
Optional. If blank, tool assumes you pay no interest on the cash back option (pay in full).
If “No”, the cash back option will estimate interest using the cash back APR.
“Even” assumes a straight-line paydown. “Interest-only” estimates interest with constant balance.
Show Work (step-by-step)
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Interest estimate uses a simple monthly approximation for speed: monthly_rate = APR/12. “Even payments” uses an average balance approximation; “Interest-only” uses full balance.

Reference

  • Cash back value: spend × (rate/100) + bonus
  • Monthly APR rate (approx): (APR/100) ÷ 12
  • Even payoff interest (approx): average_balance × monthly_rate × months
  • Average balance (even payoff): spend ÷ 2
  • Interest-only interest (approx): spend × monthly_rate × months
  • Break-even spend: where cash back value ≈ interest saved by low APR

FAQ

When does cash back win?

Usually when you pay in full (no interest) or when the APR difference is small and the cash back rate/bonus is meaningful.

When does low-interest win?

When you’ll carry the balance for months and the APR difference is large enough that interest saved beats the cash back.

Is this exact to my card statement?

No—cards typically use daily compounding and statement-cycle rules. This is a fast, transparent estimate for comparing promos.

Tool Info

Last updated:

Updates may include additional payoff models and edge-case handling.