EV Battery vs Gas Tank: What’s the Difference?

Built from fueleconomy.gov and EPA figures (the 33.705 kWh gallon-equivalent and official energy-flow data), EIA price data for November 2026, DOE Fact of the Week releases, and Paren’s Q2 2026 fast-charging price index. Prices are dated where they appear.

Here is the comparison in one number: a gallon of gasoline holds 33.7 kilowatt-hours of energy, so the 75 kWh battery in a typical long-range EV carries the raw energy of about 2.2 gallons of gas. Judged on stored energy alone, the contest looks absurd — a family SUV’s 14.5-gallon tank holds roughly 489 kWh, about six and a half times as much. Yet the EV goes about as far on its ‘2.2 gallons’ as the SUV goes on a full tank, because the two machines waste wildly different amounts of what they carry.

That gap — storage versus efficiency — is the whole subject of this page. Below: where the 33.7 figure comes from and why it is 33.7 and not a rounder number, how far real EVs and their gasoline counterparts actually go per fill, what a fill costs on each side at November 2026 prices (including the one case where charging costs more), how long each refill takes, and what the weight difference really consists of.

Quick answer
One gallon of gasoline = 33.7 kWh (the EPA’s official conversion), so a 60–100 kWh EV battery holds the raw energy of roughly 1.8–3.0 gallons. The EV still travels 250–320 miles on that because it turns about 77–82% of the energy from the wall into motion, against 12–30% for a gasoline car — about 3.9× less input energy per mile in a like-for-like comparison.

Key figures: 75 kWh battery ≈ 2.2 gallons of raw energy · 14.5-gallon SUV tank ≈ 489 kWh · Cost per mile (Nov 2026): home charging 5.3¢ vs gasoline 13.8¢ — but public fast charging 15.6¢ · Refill: ~5 min (gas) vs 18–36 min (fast charge, 10–80%)

The Official Conversion: One Gallon Equals 33.7 kWh

The 33.7 kWh figure is not an approximation invented by journalists — it is the EPA’s official gasoline-gallon equivalent, and it has a precise basis.

Where does the 33.7 kWh figure come from?

The EPA sets one gallon of gasoline equal to 33.705 kWh for its fuel-economy calculations, and fueleconomy.gov prints 33.7 kWh on every EV’s listing as the yardstick behind MPGe. The number is a lower-heating-value figure: 33.705 kWh corresponds to exactly 115,000 Btu, inside the official 112,114–116,090 Btu-per-gallon LHV range for gasoline. That basis matters because a different figure circulates widely — about 120,000 Btu per gallon — and gets paired with 33.7 kWh as if they matched.

They do not: 120,286 Btu is the gross (higher) heating value, and it converts to about 35.25 kWh. So when a page says a gallon ‘contains 120,000 Btu, or 33.7 kWh’, it has mixed two different measurements; the EPA’s 33.7 is the consistent one, and it is the one used throughout this page.

What should you watch for in the table?

Two cautions belong with this table. First, it uses usable capacity — the energy the car can actually spend — because gross (total) capacity includes a protective buffer the driver never touches; mixing the two is the most common arithmetic error on this topic, and it is how a widely copied comparison table came to pair one truck’s smaller battery with its bigger battery’s range. Second, raw energy is only the storage side of the story. What each machine does with its store is the next section — and it reverses the conclusion.

Why the Small “Tank” Still Goes 300 Miles: Efficiency

A gasoline car throws away roughly three-quarters of its fuel’s energy before it reaches the road; an EV wastes about a fifth of what it draws from the wall.

How much energy reaches the wheels?

Fueleconomy.gov’s energy-flow accounting puts the share of a gasoline car’s fuel energy that actually reaches the wheels at 12–30%, depending on driving pattern — the rest leaves as engine heat, exhaust, driveline friction and idling. An EV measured the same honest way — from the wall outlet, including the roughly 16% lost in charging — delivers 77–82% of its input energy to the road when regenerative braking is counted. (An even higher figure, 87–91%, describes battery-to-wheel efficiency alone, before charging losses; pages that set it against a gasoline car’s tank-to-wheel number are comparing two different measurements.)

The like-for-like arithmetic: a 2025 Tesla Model Y Long Range AWD draws 0.290 kWh from the wall per mile (29 kWh/100 mi, 117 MPGe, EPA). A 2025 Toyota RAV4 AWD burns 1.124 kWh of fuel energy per mile (30 mpg × 33.705 kWh). The gasoline SUV consumes about 3.9× more input energy for every mile — which is why 2.2 ‘gallons’ of battery matches a 14.5-gallon tank.

What about the ‘two gallons’ objection?

This is also the correct answer to the most common objection to the 33.7 figure — ‘if a battery only holds two gallons, EVs must be a scam’. The battery does hold two gallons’ worth of energy. It simply spends it at roughly four times the efficiency, and it recovers some of it again every time the car slows down, something no gasoline tank can do. Range comparisons that ignore the efficiency leg are not scepticism; they are half an equation.

Real Cars, Real Tanks: Range per Fill

Put the two stores into comparable vehicles and the range gap nearly vanishes — except at the heavy-truck end, where gasoline’s storage advantage is real.

What do the truck rows show?

Read the truck rows carefully, because they are the honest exception. The gasoline F-150 stores about 9.3 times the Lightning’s raw energy and goes about 2.1 times as far — for towing and long rural hauls, that stored-energy advantage is genuine and no efficiency figure makes it disappear. In the car and crossover rows, by contrast, the EV’s efficiency closes almost all of a six-fold storage gap.

What about cars, hybrids and the real world?

The hybrid row is the reality check in the other direction: a good hybrid stretches its tank furthest of all per fill, while still consuming about three times the EV’s input energy per mile. Real-world range runs below these EPA figures for both technologies — our EPA range vs real-world range guide works through how far below, and why.

What a Fill Costs: Per Tank and Per Mile

At November 2026 prices, filling an EV at home costs about a quarter of filling its gasoline counterpart — and filling it on a public fast charger can cost slightly more than gasoline.

What does a fill cost at home?

The inputs, dated so you can redo the maths whenever prices move: the EIA’s US average for regular gasoline was $4.153 per gallon in the week ending 2 November 2026, and the average residential electricity price was 18.16 cents per kWh (August 2026, the latest published). On those prices, filling the RAV4’s 14.5-gallon tank costs about $60.22.

Filling the Model Y’s battery from empty at home costs about $16.38 — and almost nobody does either from empty, so the per-mile figures are the fairer comparison: 5.3 cents per mile for the home-charged Model Y against 13.8 cents per mile for the RAV4. Over 12,000 miles a year, that is roughly $640 against $1,660 — a saving of about $1,020 a year.

What changes at a public fast charger?

Now the caveat no brochure prints. Public DC fast charging in the US averaged 53.8 cents per kWh in Q2 2026 (Paren’s measured index; there is no official one). At that price the same Model Y costs about 15.6 cents per mile — slightly MORE than the gasoline RAV4. Home charging is where the EV’s running-cost advantage lives; a driver who relies entirely on public fast chargers gives most of it back. Any version of this comparison that quotes only the home rate — or only the fast-charge rate — is selling something.

Refill Time: Five Minutes Against the Clock — and the Overnight Answer

Gasoline’s refill speed is its most durable advantage: a pump moves energy at a rate no charger approaches — but the comparison changes when the car fills while you sleep.

How fast is each refill?

A gasoline fill takes roughly five minutes for a full tank — call it 400-plus miles of range at up to about 200 miles of range per minute of pumping, an estimate no charging technology matches. The fastest EVs charge 10–80% in about 18 minutes (Hyundai and Kia’s 800-volt cars, manufacturer figures), adding range at roughly 12 miles per minute; a 400-volt car such as the Ford Mustang Mach-E takes around 32–36 minutes for the same window on Ford’s figures. Tesla’s Supercharger network sits between those poles. On a road trip, the gasoline car wins this section outright, and it is not close.

What changes when the car fills overnight?

The counterweight is where the minutes are spent. A home-charged EV leaves full every morning without any stop at all — the five-minute gasoline fill, repeated weekly, is time the EV driver simply never spends, and the fast charger only enters their life on long trips. Measured in driver time per year rather than minutes per fill, the comparison inverts for the majority of owners who can charge at home — and stays lost for those who cannot.

Weight and Size: What the Difference Really Consists Of

Gasoline wins energy density by about 73 to 1 per kilogram — and then gives most of the advantage back through efficiency and the engine itself.

How dense is each store?

The storage numbers first. Gasoline carries roughly 12,260 Wh of raw energy per kilogram, and a gallon weighs only about 6.0–6.3 pounds — a RAV4’s full tank holds its ~489 kWh in about 90 pounds of fuel. A lithium-ion pack manages roughly 150–260 Wh/kg at pack level: the Model 3 Long Range’s pack, at about 480 kg (1,058 lb) for 80.5 kWh gross, works out near 168 Wh/kg (Tesla publishes neither the weight nor the capacity; these are EPA-filing and teardown-derived figures).

Per kilogram of stored energy carrier, gasoline is about 73 times denser. That is a real, structural advantage, and it is why aircraft and heavy trucks are not battery-powered.

What does the whole vehicle weigh?

But the pack is not the whole vehicle. The gasoline car’s 90 pounds of fuel comes with an engine and transmission weighing several hundred pounds, an exhaust and cooling system, and a fuel system — while the EV’s motor is compact and its ‘tank’ doubles as the floor structure. The result at vehicle level is a difference of hundreds of pounds, not the thousands the density ratio suggests, and the EV carries its weight low and central. Our dedicated guide to how much an EV battery weighs breaks the pack weights down model by model.

MPGe: The Same Number Wearing a Label

MPGe is not a separate efficiency technology — it is the 33.7 kWh conversion restated as miles per gallon-equivalent.

When fueleconomy.gov rates the Model Y at 117 MPGe, it is saying the car travels 117 miles on 33.705 kWh drawn from the wall — exactly one ‘gallon’ of the conversion in the first section. That is all MPGe ever means, which makes it the easiest score on the window sticker to sanity-check: divide an EV’s range by its usable battery size and you have its rough miles-per-kWh; multiply by 33.705 and you have its MPGe neighbourhood.

It also means MPGe comparisons inherit the same caution as the raw conversion — the figure measures energy use, honestly and from the wall, but says nothing by itself about cost, which depends on whether the kWh came from a home outlet or a fast charger.

The Environmental Difference, Honestly Stated

The EV has no tailpipe; everything upstream of that depends on where its electricity comes from — and that is as precise as the honest answer gets.

A gasoline car emits its carbon at the tailpipe, mile by mile, wherever it drives; its fuel’s energy took refining and transport energy to produce as well. An EV emits nothing at the car, and its upstream footprint is the footprint of the grid that charged it — small on a hydro- or nuclear-heavy grid, larger on a coal-heavy one, and shrinking as grids clean up, while the gasoline car’s per-mile figure is fixed for its life.

The battery’s manufacturing footprint is real and front-loaded; the gasoline car’s is spread across every gallon it will ever burn. This page deliberately puts no single percentage on the comparison: the widely repeated figures for it depend on grid, vehicle and study assumptions, and a number without those stated is decoration, not information.

Frequently Asked Questions

How many gallons of gas is an EV battery equivalent to?

In raw energy, divide the battery’s usable size by 33.7: a 40 kWh battery ≈ 1.2 gallons, 60 kWh ≈ 1.8, 75 kWh ≈ 2.2, and 100 kWh ≈ 3.0 gallons. In distance travelled, the same battery goes roughly as far as 10–14 gallons of gasoline in a comparable car, because the EV converts about 77–82% of its wall energy to motion against the gasoline car’s 12–30%.

Why is one gallon of gas equivalent to 33.7 kWh?

Because that is the energy content the EPA assigns to a gallon of gasoline: 115,000 Btu on a lower-heating-value basis, which converts to 33.705 kWh. The roughly 120,000 Btu figure you may see quoted is the higher heating value; it converts to about 35.25 kWh, and pairing it with 33.7 kWh mixes two different measurements.

Is it cheaper to fill an EV battery or a gas tank?

At November 2026 US average prices, filling at home costs about $16 for a long-range EV against about $60 for a comparable SUV’s tank — 5.3 vs 13.8 cents per mile. On public DC fast chargers (US average 53.8 cents/kWh in Q2 2026), the EV costs about 15.6 cents per mile, slightly more than the gasoline car. Where you charge decides the answer.

How much does it cost to charge an EV for 300 miles?

At the Model Y’s EPA consumption (29 kWh per 100 miles from the wall), 300 miles takes 87 kWh: about $15.80 at the average residential rate of 18.16 cents, or about $46.80 at the average public fast-charging price of 53.8 cents. The same 300 miles in a 30-mpg gasoline car takes 10 gallons — about $41.53 at November 2026 prices.

What is the 80% rule for EVs?

It is the common practice of keeping the battery between about 20% and 80% charge for daily driving, charging to 100% only for trips, because lithium-ion cells age fastest at the extremes. It has a gasoline parallel nobody follows: it is the equivalent of running a fuel tank between a quarter and three-quarters full — harmless advice for a battery, pointless for a tank.

Are EV batteries worse for the environment than gas tanks?

The two are not really comparable objects: a tank is a steel or plastic container; a battery is the fuel store and part of the drivetrain at once. The battery’s manufacturing footprint is significantly larger than a tank’s and is paid once; the gasoline car’s footprint continues with every gallon burned over its life. Which side of the ledger wins for a given driver depends mainly on their electricity grid and how many miles they drive.

Conclusion

A battery and a gas tank store energy at opposite extremes: the tank holds far more, the battery wastes far less — and every honest comparison has to carry both halves.

The storage half belongs to gasoline, decisively: 33.7 kWh in a gallon that weighs about six pounds, 489 kWh in an ordinary SUV tank, over 1,200 kWh in a big pickup’s — against the two to four ‘gallons’ a typical EV battery holds. The efficiency half belongs to the EV just as decisively: about 3.9 times less input energy per mile in a like-for-like comparison, which is why the ranges converge anyway, why home charging costs a quarter as much per mile, and why the gasoline car’s remaining wins are refill speed and stored energy for heavy work — real wins, honestly kept on this page.

So ‘which is better’ resolves into ‘better at what’. For stored energy per kilogram and five-minute refills: the tank, and nothing on the horizon changes it. For turning stored energy into miles, and for the cost of those miles when charged at home: the battery, by a wide and widening margin. The 33.7 number is where the comparison starts — not, as it is so often quoted, where it ends.