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EV Charging Cost & Road Trip Calculator

Estimate your cost per charge and per mile, then compare a road trip’s energy cost against an equivalent gas vehicle. Accounts for charging losses from AC-DC conversion and battery heat.

Built and maintained by Paul Clark, Redmoon Software · Last verified · Sources

When to use this

Use this before buying or leasing an EV, or before a long road trip, to see your real cost per mile at home charging rates and to compare a specific trip’s energy cost against a gas alternative.

How it compares

Unlike a simple cost-per-mile estimate, this calculator separately accounts for charging losses and lets you directly compare a specific trip against a chosen gas vehicle’s mpg and local gas price, rather than relying on a generic EV-vs-gas rule of thumb.

Enter your values below. Calculations run locally as you type.

Vehicle & charging

Charging cost

Usable range / charge
263 mi
75 kWh × 3.5 mi/kWh
Cost / full charge
$13.44
$0.051 / mile

Road trip vs. gas

EV energy cost
$15.36
300 mi trip
Gas equivalent
$35.00
@ 30 mpg, $3.50/gal
Savings
$19.64
cheaper than gas

Charging at home costs $0.051/mile. Over a 300-mile trip, that's $15.36 in electricity versus $35.00 for a 30-mpg gas vehicle — a savings of $19.64.

How it works

Usable range per charge is your battery’s capacity in kWh multiplied by your vehicle’s efficiency in miles per kWh.

Cost per charge adds charging losses on top of the electricity used, since some energy is lost converting AC power to DC and conditioning the battery, then multiplies by your electricity rate.

For a road trip, the calculator compares the electricity cost of covering the distance against the cost of the same distance in a comparison gas vehicle at your chosen mpg and gas price.

FAQs

Why do charging losses matter so much?

Charging losses (typically 10–15%) come from converting AC power from the wall to DC for the battery, plus energy spent conditioning the battery to a safe temperature. That lost energy still shows up on your electricity bill even though it never reaches the wheels.

How much more expensive is public DC fast charging than home charging?

DC fast charging is usually 2–3× the cost per kWh of home charging, since networks price in demand charges, real estate, and equipment costs. Charging at home overnight on a residential rate is almost always cheaper per mile.

Why does my efficiency (mi/kWh) change so much?

Efficiency drops at highway speeds due to aerodynamic drag, and drops further in cold weather because of cabin heating and battery conditioning. Mild city driving in warm weather gives the best mi/kWh; a winter highway road trip gives the worst.

Does this calculator include the price of the vehicle itself?

No — it only compares the marginal cost of energy (electricity vs. gasoline) for the miles driven. It does not account for differences in purchase price, maintenance, or incentives.

Worked example

Input

Battery 75 kWh, efficiency 3.5 mi/kWh, home rate $0.16/kWh, 12% charging losses, 300-mile trip vs. a 30-mpg gas car at $3.50/gal.

Output

Cost per full charge: $13.44 ($0.051/mile). Trip energy cost: $15.36 vs. $35.00 in gas — a savings of $19.64.

The 75 kWh battery provides 262.5 miles of usable range per charge. Charging losses add 12% on top of the raw energy pulled, so a full charge costs $13.44 at $0.16/kWh. Over the 300-mile trip, electricity costs $15.36 versus $35.00 for the equivalent gas vehicle.

Common pitfalls

  • Ignoring charging losses understates your real cost — the battery pack itself never receives 100% of the energy pulled from the wall.
  • Using a public DC fast-charging rate instead of your home rate will make road-trip costs look artificially low if you actually charge mostly at home.
  • Efficiency (mi/kWh) is not constant — highway speed, cold weather, and cargo/passenger load can all reduce it well below the EPA-rated figure, understating real trip cost.

Charging losses are not a rounding error

The default assumes 12% losses between the wall and the battery, and that figure is doing real work. AC charging loses energy in the onboard charger and to battery thermal management, commonly 10–20% on a home charger, so the kWh your meter records is meaningfully more than the kWh the battery gains.

Cold weather makes it worse, sometimes considerably: preconditioning the pack before it can accept charge draws energy that never reaches the battery at all. A winter cost per mile noticeably above the summer figure is normal rather than a fault.

Comparing against petrol honestly

The comparison uses your efficiency in miles per kWh against a petrol vehicle's mpg and fuel price. The defaults — 3.5 mi/kWh and $0.16/kWh against 30 mpg at $3.50 — produce the large gap people expect, and both sides are sensitive to inputs that vary hugely.

The electricity rate is the biggest lever and the one least likely to be a single number. On time-of-use tariffs, charging overnight and charging at dinner time can differ by a factor of three, and public rapid charging is frequently several times the home rate — often enough to erase the advantage against petrol entirely.

Use your actual observed mi/kWh rather than the manufacturer figure. Real-world efficiency falls with speed, cold and load, and the gap between rated and observed is usually larger for EVs than for petrol cars.

Where these numbers come from

The method behind this tool, so you can check it rather than take it on trust.

  • Charging losses vary by vehicle, charger and temperature.

    The efficiency figure is an input because AC charging losses commonly run 10–20%, and cold weather pushes them higher. Your utility tariff is the other half and is never a single number if you are on time-of-use pricing.

Read more about this

· 7 min read

Why your EV draws more kWh than its battery holds — charging losses explained

The two numbers that make EV running-cost estimates wrong: charging losses (you pay for more energy than reaches the battery) and real-world efficiency (mi/kWh swings with speed, cold, and terrain). Here is how each one moves your cost per mile.
· 8 min read

What it actually costs to charge an EV vs. fill up with gas

Why a "75 kWh battery" costs more than 75 kWh to charge, the real price gap between home and DC fast charging, and a worked road-trip cost comparison against a gas car.

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