An EV using 30 purchased kWh per 100 miles costs $4.80 at $0.16/kWh. A gasoline car achieving 30 MPG costs $11.67 per 100 miles at $3.50 per gallon. But at $0.50/kWh, that same EV energy assumption costs $15.00. Where you charge can change the result.
These are illustrative US scenarios, not current national prices or a claim about a particular vehicle. This guide shows the calculation so you can substitute local rates, actual consumption and your home/public charging mix. Sources checked November 14, 2026. No tax credit, rebate or purchase incentive is assumed.
The two formulas you need
EV energy cost per 100 miles = purchased kWh per 100 miles × price per kWh. Add relevant session fees, subscriptions, parking or other charging costs separately.
Gasoline cost per 100 miles = 100 ÷ MPG × price per gallon. Use US gallons and a comparable driving pattern. A highway-only MPG figure is not a fair comparison with an EV figure from cold-weather city trips.
The EPA electric-vehicle label gives consumption in kWh per 100 miles. MPGe is an energy-equivalence measure, not the dollar price you pay. For a cost comparison, use kWh/100 miles and your electricity price.
Compare home charging, public charging and gasoline
The first table fixes EV consumption at an assumed 30 purchased kWh/100 miles and gasoline economy at 30 MPG. Prices are chosen examples, not offers from a utility or charging network.
| Scenario | Assumed energy price | Cost per 100 miles |
|---|---|---|
| EV: lower-cost charging example | $0.12/kWh | $3.60 |
| EV: home charging example | $0.16/kWh | $4.80 |
| EV: higher electricity-rate example | $0.30/kWh | $9.00 |
| EV: public charging example | $0.50/kWh | $15.00 |
| Gasoline: lower-price example | $3.30/gallon | $11.00 |
| Gasoline: middle example | $3.50/gallon | $11.67 |
| Gasoline: higher-price example | $4.00/gallon | $13.33 |
The Department of Energy’s consumer guide notes that public charging, especially DC fast charging, generally costs more than home charging. Your actual options can differ. A renter who mainly charges publicly should not base a purchase on a homeowner’s overnight rate.
Do not count charging losses twice
FuelEconomy.gov explicitly says its plug-in kWh/100-mile estimates include charging losses. Adding another blanket charging-loss percentage to those figures would double-count that allowance.
Dashboard trip consumption may use a different measurement boundary. If it reports energy consumed from the battery, electricity bought at the wall can be higher. For an original hypothetical example, 27kWh of battery use with 90% charging efficiency requires 27 ÷ 0.90 = 30kWh purchased. The 90% is an assumption, not a universal efficiency rating.
For an ownership log, compare charging receipts or dedicated charger measurements with miles traveled over a representative period. Start and finish at similar battery charge levels; otherwise you may count energy bought for miles you have not driven yet. Include energy used while parked and preconditioning where your measurement captures it.
Worked example: 80% home charging and 20% public charging
Suppose the EV uses the same 30 purchased kWh/100 miles in both situations, with 80% of purchased energy at $0.16/kWh and 20% at $0.50/kWh. This is an energy share, not a count of charging sessions.
Blended electricity price: (0.80 × $0.16) + (0.20 × $0.50) = $0.228/kWh.
EV cost: 30 × $0.228 = $6.84 per 100 miles.
Gasoline cost: 100 ÷ 30 × $3.50 = $11.67 per 100 miles.
At an assumed 12,000 miles per year, the EV energy cost is 120 × $6.84 = $820.80. The gasoline calculation is 12,000 ÷ 30 × $3.50 = $1,400. The difference is $579.20 per year, before charging fees and other ownership costs.
If consumption differs between commuting and road trips, calculate their energy separately before blending. For public DC charging, actual billed kWh and fees are preferable to treating an AC label figure as an exact session forecast.
Find your break-even electricity price
For energy alone, divide the gasoline cost per 100 miles by the EV’s purchased kWh per 100 miles. With the main example: (100 ÷ 30 × $3.50) ÷ 30 = $0.389/kWh, approximately. Below that rate, EV energy is cheaper under these assumptions; above it, gasoline is cheaper.
| Gasoline comparison at $3.50/gallon | Gas cost per 100 miles | EV break-even rate at 30kWh/100 miles |
|---|---|---|
| 25 MPG | $14.00 | $0.467/kWh |
| 30 MPG | $11.67 | $0.389/kWh |
| 40 MPG | $8.75 | $0.292/kWh |
| 50 MPG | $7.00 | $0.233/kWh |
An efficient gasoline hybrid changes the comparison substantially. So does a large EV that consumes more electricity. Compare the vehicles you would realistically buy, with similar space and use, rather than pairing an efficient compact EV with an unusually thirsty gasoline vehicle.
How much will the EV add to your home electricity bill?
Using the 12,000-mile, all-home version of our example gives 12,000 ÷ 100 × 30 = 3,600kWh/year. At the assumed $0.16/kWh, that adds $576/year, or an average $48/month in energy charges. Seasonal driving and rates can make individual months very different.
In the 80/20 example, only 2,880kWh is purchased at home, costing $460.80; the remaining $360 is public charging. Do not add the all-home $576 estimate to the mixed-charging total—that would count some energy twice.
Use the incremental rate for extra consumption, including applicable variable delivery charges and taxes. Existing fixed charges do not necessarily rise when you charge a car. However, a new plan, separate meter or higher tariff tier can change the calculation. EIA explains that its published price data are not individual utility tariffs or peak/off-peak rates. Get the actual tariff from your utility.
Public charging fees can change a close comparison
Electrify America explains that pricing depends on location, plan, delivered energy and, at some stations, time of day. Check the charger’s displayed price and applicable fees before starting. Other networks may use different billing methods.
For an illustrative membership decision, suppose a plan costs $8/month and reduces your rate by $0.08/kWh. It needs $8 ÷ $0.08 = 100kWh/month of eligible charging just to cover the subscription. Those figures are invented calculation inputs, not an advertised network plan.
Include parking, idle and session fees where they apply. A low advertised kWh rate may not be your effective cost for short sessions or infrequent use. Keep recurring fees separate so you can compare months with different charging volumes.
Winter, solar and long-distance estimates
Cold weather can increase energy per mile, and highway use can differ from your normal commute. Run a separate seasonal case instead of multiplying one favorable month across the year. Our winter EV range guide includes a journey-energy example.
Home solar is not automatically free charging: consider installation cost and the value of electricity you would otherwise export. Use the applicable export tariff and actual charging schedule. Our solar production versus utility bill guide explains the measurement boundaries.
At 200,000 miles, 30kWh/100 miles requires 60,000kWh. At fixed illustrative rates of $0.12–$0.18/kWh, that is $7,200–$10,800. A 30-MPG vehicle at $3.30–$4.00/gallon uses $22,000–$26,667 of gasoline. These are arithmetic scenarios, not forecasts of future prices, maintenance or vehicle lifespan.
Energy savings are only one part of ownership cost
Compare purchase price, financing, insurance, depreciation, registration, maintenance, tires and charging installation separately. Request a site-specific installation quote; our home EV charging guide explains what to check. Fuel savings alone do not prove that replacing a paid-off working car is financially worthwhile.
Your quick comparison checklist
Write down the exact vehicles, annual miles, comparable efficiency figures, your home tariff, expected public-charging energy share and extra fees. Calculate per-100-mile cost first, then annual energy cost. Finally add the ownership costs that actually differ between your alternatives.
The short version
Home charging can make an EV inexpensive to drive, while costly public charging can narrow or reverse the energy-cost advantage. Use purchased energy, real local rates and your charging mix. A transparent calculation is more useful than a universal claim that one powertrain is always cheaper.
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