Cash Back vs Low Interest Credit Card Calculator
Compare a cash back credit card against a low interest rate card.
Find which saves you more based on spending habits and carried balance.
Cash Back vs. Low Interest: The Real Math
Choosing between a cash back credit card and a low-interest card depends almost entirely on one question: Do you carry a balance each month?
How Cash Back Cards Work
A cash back card gives you a percentage of every purchase back as a reward. Common rates:
- Flat-rate cards: 1.5% – 2% on all purchases
- Category cards: 3% – 5% on groceries, gas, dining; 1% elsewhere
- Premium cards: Up to 6% in specific categories (often with an annual fee)
However, these cards typically carry high APRs — often 19% – 29% — which can easily erode your rewards if you carry a balance.
How Low-Interest Cards Work
Low-interest cards offer a reduced APR — typically 8% – 18% — at the cost of little or no rewards. They are designed for people who regularly carry a balance and want to minimize interest charges.
The Key Formula
Monthly interest cost = Carried Balance × (APR / 12)
Monthly rewards earned = Monthly Spending × Cash Back Rate
Net monthly benefit of cash back card = Rewards Earned − Interest Cost on Cash Back Card
Net monthly benefit of low-interest card = Rewards Earned − Interest Cost on Low-Interest Card
Who Should Choose Each Type?
| Situation | Best Card |
|---|---|
| You pay in full every month | Cash back card |
| You carry any balance regularly | Low-interest card |
| You carry a large balance | Low-interest card (by far) |
| You have high spending but low balance | Cash back card |
The Breakeven Balance
There is a specific carried balance at which both cards cost the same. Below that balance, the cash back card wins; above it, the low-interest card wins. This calculator shows you that exact breakeven point.
The Real Cost of Rewards
For every 2% cash back card with a 24% APR, carrying just $100 of balance costs $2/month in interest — erasing a cash back reward on $100 of spending. At $1,000 carried balance, the interest ($20/month) easily outweighs most rewards earned.
Always treat credit cards as a convenience tool, not a financing tool, to maximize the value of rewards.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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