Gas vs EV Cost Calculator

About the Gas vs EV Cost Calculator

Comparing a gasoline car with an electric one is harder than it looks, because the two vehicles report efficiency in different units and buy energy in different packages. A gas car is rated in miles per gallon and fueled at a pump priced per gallon. An EV is rated in miles per kilowatt-hour, or kilowatt-hours per 100 miles, and charged from a meter priced per kWh. This calculator translates both into the one unit that matters for budgeting, cost per mile (or per kilometer), then scales it by how far you drive in a year to show annual energy costs side by side.

The headline output is the annual difference, but the per-mile figures are often more instructive. A gas car at 31 MPG with gasoline near $3.65 costs roughly 12 cents a mile to fuel, while an EV at about three miles per kWh with electricity near 22 cents can cost roughly 7 cents a mile. Those numbers are not forecasts; they simply show how the two vehicles respond to the prices you enter. Change the electricity rate or the gas price and you can see exactly where the advantage grows or disappears.

The comparison covers fuel and electricity only, on purpose. Purchase price, financing, insurance, maintenance, depreciation, registration fees, and charger installation are all real parts of ownership, and they can move the total in either direction. Treat this tool as the energy chapter of a longer story: a fast, transparent way to quantify how much you would save or spend per year on the energy that moves the car, which you can then weigh against everything else.

When to Use It

How to Use It, Step by Step

1. Select U.S. or metric units. In U.S. mode you enter miles, MPG, price per gallon, and miles per kWh; in metric mode you enter kilometers, L/100km, price per liter, and kWh per 100 km.
2. Enter Annual miles driven (or Annual distance driven in metric). The defaults are 12,000 miles or 20,000 km. Use your actual yearly mileage from service records, a recent odometer comparison, or insurance paperwork.
3. Enter Gas vehicle MPG (or Gas fuel consumption in L/100km). Use the real-world figure for the specific gas car you would otherwise drive, not an average of all gas cars.
4. Enter the Gas price, in dollars per gallon or per liter. Use what you typically pay at local stations, and consider using a slightly higher or lower number to test sensitivity.
5. Enter EV efficiency in miles per kWh, or kWh per 100 km in metric mode. This appears on the EPA label as kWh per 100 miles; to convert that to miles per kWh, divide 100 by the label figure.
6. Enter your Electricity price per kWh. For home charging, use your utility's rate; if you will rely on public chargers for a large share of energy, enter a blended price that reflects that mix.
7. Press Compare Gas vs EV Costs and read the summary sentence and the highlighted Annual difference, then compare Gas cost per mile with EV cost per mile.
8. Run alternative scenarios by raising the gas price, changing the electricity rate, or entering a more efficient gas model. Noting which input moves the answer most tells you where to focus your research.

Understanding Your Results

Gas cost per mile and EV cost per mile are the foundation: each is a price divided by an efficiency. Annual gas cost and Annual EV cost multiply those by the distance you drive, and Annual difference is the gap, displayed as a positive number with the summary sentence saying which vehicle is cheaper to run. Dollar amounts in the annual lines are rounded to whole dollars, while per-mile figures show three decimals, so small differences may appear when you check by hand.

To judge whether the result is plausible, check the efficiencies you entered. Gas passenger cars commonly range from the teens to the high 30s in MPG, and hybrids go higher. Electric cars commonly achieve about 2.5 to 4.5 miles per kWh depending on size, speed, and weather, though some fall outside that. If your annual EV cost looks absurdly low or high, check that you did not confuse miles per kWh with kWh per 100 miles, since those two figures move in opposite directions.

The most useful next step is a break-even test. The EV's per-mile cost equals the gas car's when the electricity price equals the gas cost per mile multiplied by the EV's miles per kWh. In the first example below, that works out to roughly 38 cents per kWh, far above typical home rates, which shows the result is robust. If your own break-even sits near your actual electricity price, then small changes in rates or driving could flip the comparison.

More Worked Examples

Tips for Better Results

• Use real-world efficiency from owners of the exact models you are comparing rather than the label alone. Highway speed, winter temperatures, and cabin heating can reduce EV efficiency noticeably, and gas cars are affected by their own versions of these factors.
• Be honest about your charging mix. If you can charge at home most of the time, your blended price will be close to your utility rate; if you depend on public fast chargers, the blended price may be much higher and the advantage shrinks.
• Compare against the gas car you would actually buy, not a generic one. A hybrid at 50 MPG narrows the energy-cost gap considerably, and the best EV choice might differ if you are cross-shopping against efficient gas cars.
• Run the numbers at your real annual mileage and also at a lower figure. If you drive very little, energy savings may be too small to offset a higher purchase price, which is useful to know before you shop.
• Look up whether your utility offers an EV or time-of-use rate. Cheap overnight pricing can cut the EV side of the comparison substantially, and it only requires charging after bedtime.
• Pair this tool's output with maintenance, insurance, depreciation, and purchase-price differences, plus any available incentives, to reach a real total cost of ownership comparison, since energy cost alone is only part of the picture.

Common Mistakes to Avoid

• Mixing up miles per kWh and kWh per 100 miles. The EPA label shows kWh per 100 miles, so divide 100 by that number to get miles per kWh before entering it in U.S. mode.
• Using a rated efficiency for one vehicle and a measured one for the other. Compare like with like, either both rated or both measured, or the result will be skewed toward whichever number is more optimistic.
• Treating the annual difference as total savings. It covers only fuel and electricity, so it ignores purchase price, interest, insurance, maintenance, and depreciation, which can swamp energy differences in either direction.
• Entering the electricity price in cents. A rate of 16 cents is entered as 0.16 dollars per kWh; typing 16 will fail the field's limit or produce nonsense if you bypass it.
• Forgetting that annual mileage drives the dollar result. If you enter 12,000 miles but actually drive 7,000, the savings are overstated by more than 70 percent, so use your real numbers.

Assumptions and Limits

• Both vehicles are assumed to achieve the efficiency you enter all year. In reality, cold weather, high speeds, towing, and short trips reduce efficiency for both types of vehicle, though the effect can be larger for EVs in winter.
• A single electricity price is used for all charging and a single gas price for all fuel purchases. Prices fluctuate, and the tool does not model tiers, demand charges, or seasonal changes.
• Only energy is compared. Maintenance, insurance, taxes, registration fees, depreciation, financing, and any charger installation cost are excluded, and incentives or fees specific to your region may change the decision.
• The tool does not apply charging losses, so the EV efficiency figure should reflect energy taken from the wall if you want to include them. Consult a financial professional for major purchase decisions.

Key Terms

Cost per mile

The energy price divided by how many miles that unit of energy delivers. It makes gasoline and electricity directly comparable.

Miles per kWh

How many miles an electric vehicle travels on one kilowatt-hour. Higher numbers indicate greater efficiency, similar to MPG for gas cars.

kWh per 100 km

The electricity an EV uses to travel 100 kilometers, the metric counterpart of miles per kWh. Lower numbers mean better efficiency.

Total cost of ownership

The sum of all costs of owning a vehicle over time, including purchase, financing, energy, insurance, maintenance, and depreciation.

Break-even price

The price of a fuel or electricity at which two vehicles cost the same to run per mile. Beyond it, one option becomes cheaper than the other.

Time-of-use rate

An electricity plan with different prices at different hours, often cheaper overnight, which suits home EV charging.