The Gas Price Where an EV Stops Being Cheaper to Fuel

The gas price where a gas car and an electric one cost exactly the same to fuel is one formula: gas price ($/gal) = gas MPG × (electricity price ($/kWh) ÷ EV efficiency (mi/kWh)). Below that price, the gas car is cheaper to fuel. Above it, the EV is. Run a common pairing — 32 MPG, 3.5 mi/kWh, $0.16/kWh, all illustrative — and the crossover lands at $1.46 a gallon. Run a more efficient gas car against a pricier electric rate and the crossover can sit above $5 a gallon. How far apart those two numbers land — and which side of a real gas price they fall on — depends entirely on which vehicles and which rates you put in. The EV vs. Gas Cost Calculator runs this arithmetic on your own numbers; this guide is the formula behind it, plus four things that move the crossover price after you've computed it.

Where the formula comes from

The calculator's cost-per-mile arithmetic is one division on each side: gas cost per mile is price per gallon divided by MPG, and electric cost per mile is price per kWh divided by mi/kWh. The two sides are equal exactly when

gas price = gas MPG × (electricity price ÷ EV mi/kWh)

Everything below that price, gasoline is cheaper per mile. Everything above it, electricity is. Because MPG and mi/kWh sit on opposite sides of a division, a more efficient gas car needs a higher gas price to lose — and a less efficient EV needs a higher electricity price to win. The crossover isn't a property of electric cars in general; it's a property of the specific pair of vehicles and the specific prices you enter.

Two worked examples

All figures below are illustrative inputs — substitute your own gas price, electricity rate, and rated efficiencies.

Pairing 1 — a common compact gas car against a common EV: 32 MPG combined, 3.5 mi/kWh, $0.16/kWh. Crossover = 32 × (0.16 ÷ 3.5) = $1.46 a gallon.

At a more ordinary gas price of $3.29/gal, the gas car costs $3.29 ÷ 32 = 10.28 cents a mile, and the EV costs $0.16 ÷ 3.5 = 4.57 cents a mile — a gap of 5.71 cents a mile. Over 12,000 miles a year (illustrative), that's about $685 a year cheaper to fuel with the EV.

Pairing 2 — an efficient gas car against a less-efficient, pricier-to-charge EV: a 45-MPG hybrid-class gas car against an EV rated 2.7 mi/kWh on a $0.32/kWh electricity rate (illustrative — some residential rates run that high). Crossover = 45 × (0.32 ÷ 2.7) = $5.33 a gallon.

In this pairing, whether the EV wins depends on the local gas price on the day you're asking, not just on "EVs are cheaper to fuel."

Four things that move the crossover after you've computed it

1. Aggressive driving and speed raise your real gas cost, not your real gas price

The Department of Energy frames speeding as an effective price increase: "you can assume that each 5 mph you drive over 50 mph is like paying an additional $0.29 per gallon for gas." Ten miles an hour over 50 is two of those increments — on the $3.29/gal example above, that's an effective $3.87/gal. At 32 MPG, that's 12.09 cents a mile against the EV's unchanged 4.57 cents, a 7.52-cent gap — about $903 a year, roughly $218 more than the posted-price example. DOE separately puts aggressive driving's toll at "roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic." Either way, this moves the same direction: it widens the EV's fuel-cost edge, because it's the gas car's real-world number that degrades, not the EV's.

2. Cold weather cuts both vehicles — but not by the same amount

DOE also publishes cold-weather penalties, and they aren't symmetric. In city driving, a conventional gas car's mileage is "roughly 15% lower at 20°F than it would be at 77°F"; an EV in mixed city and highway driving runs "roughly 39%" lower, with range down about 41%. Apply both to Pairing 1: the gas car's 32 MPG becomes 27.2 MPG (12.10 cents a mile), and the EV's 3.5 mi/kWh becomes about 2.14 mi/kWh (7.49 cents a mile). The gap narrows to 4.60 cents a mile — about $552 a year, roughly $133 less than the mild-weather example. The EV is still cheaper to fuel in this pairing; it's just a smaller edge in winter than the sticker-rating math implies, because the EV's cold-weather penalty is the larger of the two.

3. The fuel blend at the pump isn't always what a spec figure assumed

DOE states that vehicles "will typically go 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on 100% gasoline." If the MPG figure you're using came from a source that tested on ethanol-free gasoline rather than from your own tank, and the gas you actually buy is a 10% ethanol blend, your real number runs a few percent lower. Applying a 3.5% cut to Pairing 1's 32 MPG gives 30.9 MPG and 10.65 cents a mile — about $45 a year more in gas cost than the figure computed on an ethanol-free assumption, again widening the EV's edge slightly.

4. This is a fueling-cost crossover, not a buying decision

Everything above answers one question: which car costs less per mile in energy. It says nothing about which car cost more to buy, and a fuel-cost win doesn't automatically repay a purchase-price gap. The federal credit that used to help close that gap — the New Clean Vehicle Credit, worth up to $7,500 under IRC section 30D — no longer applies: the IRS states it "is not available for vehicles acquired after Sept. 30, 2025." Whether a given EV's fuel saving actually repays what it cost extra to buy is a separate calculation, covered in Does a Hybrid or EV Pay for Itself? and the Break-Even Mileage Calculator it funnels to — not this one.

One more caution worth stating plainly: the mi/kWh figure that belongs in this formula is the EPA-rated one, measured at the wall outlet, not the number on the car's own dashboard, which is measured at the battery and excludes charging losses. Using the dashboard figure overstates the EV's efficiency and understates its real cost per mile. That distinction, and three others like it, is covered in full in EV vs. Gas: What a Mile Really Costs.

Frequently asked questions

What's the formula for the crossover gas price?

Gas price ($/gal) = gas MPG × (electricity price ($/kWh) ÷ EV efficiency (mi/kWh)). It comes directly from setting the two cost-per-mile divisions — price per gallon over MPG, and price per kWh over mi/kWh — equal to each other and solving for the gas price.

Does a lower crossover price mean the EV always wins?

It means the EV wins whenever the actual gas price is above the crossover. A $1.46/gal crossover, as in Pairing 1 above, means gas has to fall a long way below typical prices for the gas car to win. A $5.33/gal crossover, as in Pairing 2, sits close enough to real-world prices that the outcome depends on the actual price of gas where and when you're asking.

Why does cold weather change the crossover, and which direction?

Because the two vehicles don't lose efficiency by the same percentage in the cold. DOE's published figures put a conventional gas car's city-driving penalty at roughly 15% at 20°F, versus roughly 39% for an EV in mixed driving. Since the EV's percentage loss is larger, cold weather narrows the EV's fuel-cost advantage — it doesn't erase it in the examples above, but it moves the number.

Does the tank's ethanol content matter to this calculation?

Yes, to the MPG side of it. DOE says vehicles typically run 3% to 4% fewer miles per gallon on a 10% ethanol blend (E10) and 4% to 5% fewer on E15, compared with 100% gasoline. If an MPG figure you're using came from an ethanol-free test rather than a real pump fill-up, your actual gas cost per mile will run a bit higher than that figure implies.

Is a lower crossover price the same as the EV being the better financial decision?

No. The crossover is about energy cost per mile only — it doesn't account for what either car cost to buy. An EV that wins comfortably on fuel can still take years to repay a higher purchase price, especially since the federal $7,500 New Clean Vehicle Credit ended for vehicles acquired after September 30, 2025. That's a break-even-on-purchase-price question, not a cost-per-mile one.

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This guide is informational only and is not professional financial or tax advice. Last reviewed: September 2026.