Credit Cards
APR vs Rewards: Worked Example When Interest Wins
Quick answer
Rewards are paid on spending; interest is charged on balances you carry. When you pay in full, rewards are pure gain. When you carry a balance, interest usually wins — fast. The worked examples below use labeled hypothetical rates (not any card's actual offer) so you can see the math and then run your own card's real numbers.
Key takeaways
- Rewards are paid on spending; interest is charged on balances you carry — the two run on different bases.
- Pay in full and rewards are pure gain; carry a balance and interest usually eats the rewards fast.
- Paying only the minimum keeps a balance alive for years and can push total interest into four figures on a modest balance.
- Before choosing a card for rewards, run your own numbers from the card agreement: real APR, penalty APR, fee, reward rate and caps.
The core math (hypothetical illustration)
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What this page does not state: No market APR or reward rate is stated. Hypotheticals are labeled as such and must not be quoted as offers.
Assume, hypothetically: a card pays 1.5% cash back and charges 24% APR. These are round teaching numbers, not a market claim.
• Spend $1,000 in a month and pay in full: rewards = $1,000 × 1.5% = $15, interest = $0 (grace period kept). Net: +$15.
• Spend $1,000, then carry a $1,000 balance for one month: rewards still $15, but one month's interest ≈ $1,000 × 24% ÷ 12 = $20. Net: −$5 — and the balance is still $1,000.
• Carry that $1,000 for six months at the same hypothetical APR (simplified, ignoring compounding and payments): interest ≈ $120, rewards on the original spend $15. Net: −$105.
That is the whole lesson in three lines: one month of carried interest can erase months of rewards.
Worked example 2: the minimum-payment trap meets rewards
Hypothetical: $2,000 balance, 24% APR (illustrative), minimum payment set as a small percentage of the balance. Paying only the minimum each month keeps the balance alive for years; total interest runs into four figures while rewards on the original $2,000 of spending were a one-time ~$30 at 1.5%. Rewards are earned once, on spending. Interest is charged repeatedly, on the balance, until it is gone. No reward rate on an ordinary card closes that gap.
Worked example 3: when rewards DO win
Hypothetical: $800/month spending, always paid in full, 2% rewards on one category. Annual rewards ≈ $800 × 12 × 2% = $192 (if all spending were in that category — in reality, category caps and mixed spending lower it). Interest: $0. Annual fee: $0 on a no-fee card. Net: +$192 (before any redemption limits). This is the only scenario where chasing rewards is rational: full payment, every month, no exceptions.
Run your own numbers (do this before choosing a card for rewards)
1. Find your card's real purchase APR, penalty APR, annual fee, and reward rate/caps in its agreement.
2. Estimate monthly spending by category, and rewards after caps.
3. Estimate the balance you actually carry (be honest — use last year's statements, not intentions).
4. Monthly interest ≈ carried balance × APR ÷ 12 (simplified; daily compounding and average-daily-balance methods vary by issuer — your statement's interest charge is authoritative).
5. If (3) × APR ÷ 12 exceeds monthly rewards, the card loses money as a rewards tool — regardless of its headline rate.
At a glance
| Pay statement balance in full | Carry a balance | |
|---|---|---|
| Grace period | Kept — purchases accrue $0 interest | Usually lost — new purchases accrue interest from purchase date |
| Rewards | Pure gain (minus any annual fee) | Quickly outweighed by interest |
| Payoff date | Every month | Undefined — set by your payment, not the card |
| Credit effect | On-time payments + low reported utilization (if timed well) | Higher utilization + interest burden; missed payments damage further |
Comparison table: pay in full vs carry a balance
What this means for you
Rewards are a rebate on spending; interest is rent on debt. The moment you carry a balance, the rent outruns the rebate — so the only rewards strategy that reliably wins is paying in full, every month, without exception.
FAQ
Are travel points different?
No — the math is the same, with point value added as a conversion step. A mile worth, hypothetically, 1 cent is just a 1% reward in disguise. Interest still wins if you carry a balance.
What about 0% intro periods?
A 0% intro period suspends interest only if you meet its terms and clear (or nearly clear) the balance before it ends, and only for the balances it covers. New purchases may not share the intro terms, and carrying an intro balance can cost you the grace period on new purchases. Read the intro terms; do not assume '0% on everything'.
Should I ever choose a card for rewards while carrying debt?
Pay off the debt first (see the debt-payoff guides and calculators). Rewards optimisation is a second-order game for people with no carried balance.
Sources
- CFPB credit-card interest and grace-period guidance (concept verified 2026-10-28).
- All APR/reward figures in this page are labeled hypothetical illustrations, not verified market offers.
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