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Gas Rewards Calculator: How Much Will You Earn Back on Fuel?

Compare two gas rewards cards side by side. Enter your monthly gas spend and see exactly which card returns more after fees, caps, and point valuations.

Gas Rewards Calculator

Compare two cards side by side. See your exact annual return.

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Citi Custom Cash earns $24 more per year at $200/month gas spend

WINNER

Citi Custom Cash

Gas rate5% cash back
Annual gas rewards$120.00
Annual fee$0
Net annual return$120.00
Effective cents per gallon17.5 cents
Break-even on feeN/A

Costco Anywhere Visa

Gas rate4% / 5% at Costco gas
Annual gas rewards$96.00
Annual fee$0
Net annual return$96.00
Effective cents per gallon14.0 cents
Break-even on feeN/A

Gas price assumed at $3.50/gal for cents-per-gallon calculation. PenFed points valued at 0.85 cents each (travel redemption).

How to Estimate Your Monthly Gas Spend

If you are not sure what you spend on gas each month, use this formula based on your daily commute:

Monthly gas cost = (Round-trip miles / MPG) x Gas price x 22 work days

Daily round trip20 MPG25 MPG30 MPG
20 miles$77/mo$62/mo$51/mo
40 miles$154/mo$123/mo$103/mo
60 miles$231/mo$185/mo$154/mo
80 miles$308/mo$246/mo$205/mo
100 miles$385/mo$308/mo$257/mo
120 miles$462/mo$370/mo$308/mo

Based on $3.50/gal and 22 work days/month. Add 20-30% for weekend/errand driving.

Reading the Results

Net annual return

This is the number that matters most. It is your total gas rewards minus the annual fee. A card earning $120 in gas rewards with a $95 fee nets only $25. A free card earning $90 nets $90. The higher net return wins.

Effective cents per gallon

Your net annual return divided by total gallons purchased. This tells you the real per-gallon discount you are earning. Compare this to station loyalty discounts (typically 3-10 cents/gallon) to see how they stack.

Break-even month

For cards with an annual fee, this shows when your gas rewards have paid off the fee. If the break-even is beyond month 12, the fee card is not worth it for your gas spend alone. Consider whether other bonus categories (groceries, travel) justify the fee.

Methodology

All card data is sourced from public issuer disclosure pages as of April 2026. Reward rates, caps, and fees reflect the most current published terms.

PenFed Platinum Rewards points are valued at 0.85 cents each, based on travel redemption value. Statement credit redemption is lower (approximately 0.70 cents). Gift card values vary by retailer.

Rotating category cards (Chase Freedom Flex, Discover it Cash Back) assume gas is a bonus category in 2 out of 4 quarters per year, which aligns with historical patterns. The $1,500 per-quarter cap is applied during bonus quarters.

Gas price is assumed at $3.50/gallon for cents-per-gallon calculations. BP Rewards Visa is calculated as a fixed 15 cents per gallon discount.

The calculator does not factor in welcome bonuses (one-time), sign-up requirements, credit score eligibility, or rewards earned on non-gas spending. It focuses purely on gas rewards to provide a fair card-to-card comparison at the pump.

Frequently Asked Questions

How do I estimate my monthly gas spend?+
The average US household spends about $150 to $200 per month on gas. To estimate yours more precisely: take your daily commute miles (round trip), divide by your car's MPG, and multiply by the local gas price. For example, at 25 MPG and $3.50/gal, a 30-mile round-trip commute costs about $4.20/day or $92/month in gas. Add weekend driving and errands, which typically adds 20-30% more.
What does 'effective cents per gallon' mean?+
Effective cents per gallon is your net annual reward (after subtracting any annual fee) divided by the total gallons you purchase in a year. It shows you the real per-gallon discount you are getting from your credit card. A card earning 5% at $3.50/gal gives you about 17.5 effective cents per gallon. A card with a $95 annual fee might only give you 8 cents per gallon after the fee is subtracted.
Should I include the welcome bonus in my calculation?+
Welcome bonuses are one-time rewards for new cardholders. If you are comparing cards as a new applicant, factor the welcome bonus into your first-year return. For example, a $200 welcome bonus adds $200 to your year-one total. But do not count on it for long-term value. The ongoing reward rate and annual fee are what matter after year one.
Why does the calculator show different results than the card's advertised rate?+
The advertised rate is the headline number (e.g., 5% cash back). The calculator factors in reward caps, annual fees, and point valuations that affect your actual return. For example, PenFed's 5x points are worth about 4.25% in real value because points redeem at 0.85 cents each. Rotating category cards like Chase Freedom Flex earn 5% only in bonus quarters, so the effective annual rate is much lower.

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