EV vs Gas Fuel Cost Comparator
Compare the monthly energy cost of driving an electric car versus a gasoline vehicle.
What this calculator does
Compare monthly EV charging cost with monthly gasoline cost for the same driving distance. It converts EV efficiency and gasoline fuel economy into comparable energy or fuel usage, then estimates monthly and yearly savings.
Inputs explained
- Monthly distance: Miles or kilometers driven each month.
- EV efficiency: mi/kWh, kWh/100mi, or kWh/100km.
- Electricity rate: Price per kWh for EV charging.
- ICE fuel economy: MPG, km/L, or L/100km.
- Gas price: Price per gallon or per liter, based on the fuel economy unit.
How it works / Method
- Convert EV efficiency to kWh per mile or kilometer.
- Multiply by monthly distance to get EV energy use and cost.
- Convert fuel economy to gallons or liters per distance for the ICE vehicle.
- Multiply by monthly distance to get gasoline use and cost.
- Subtract EV cost from ICE cost to estimate savings.
Formula(s) used
EV_kWh = distance * kWh_per_unit
EV_cost = EV_kWh * electricity_rate
Gas_used = distance / MPG or distance * (L/100km) / 100
Gas_cost = Gas_used * fuel_price
Monthly_savings = Gas_cost - EV_cost
Units: distance in mi or km, electricity rate in currency per kWh, gas price per gallon or liter.
Inputs
Comparison
EV Monthly Cost
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Gas Monthly Cost
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Monthly Savings
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Yearly Savings
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Step-by-step example
Example inputs: 1,000 miles per month, EV efficiency 3.3 mi/kWh, electricity rate $0.16/kWh, gasoline vehicle 28 MPG, gas price $3.75/gal.
- EV energy: 1,000 * (1 / 3.3) = 303 kWh.
- EV cost: 303 * $0.16 = $48.48 per month.
- Gas used: 1,000 / 28 = 35.7 gallons.
- Gas cost: 35.7 * $3.75 = $133.93 per month.
- Monthly savings: $133.93 - $48.48 = $85.45.
- Yearly savings: $85.45 * 12 = $1,025.40.
Use cases
- Compare monthly fuel costs between an EV and a gasoline car.
- Estimate savings after switching to an EV.
- Test how fuel prices affect the savings gap.
- Compare different EV efficiencies or gas vehicle MPG.
- Plan a household budget based on monthly driving distance.
- Validate savings before investing in home charging.
Assumptions & limitations
- Charging losses are not included in EV energy use.
- Public charging fees or session costs are not modeled.
- Fuel prices are treated as constant for the month.
- Maintenance, depreciation, and insurance are not included.
- Fuel economy can vary with speed, terrain, and weather.
- Results are estimates for planning, not a guarantee.
Disclaimer: Results are estimates for planning only. Real world costs vary by driving behavior and energy prices.
Frequently Asked Questions
Calculate each car's monthly fuel cost using the same monthly miles, then subtract. EV side: monthly miles × kWh per mile × electricity rate × 1.10 (for losses). Gas side: monthly miles ÷ MPG × gas price per gallon. Run both with the same mileage baseline. Example for 1500 km/month: EV at 0.18 kWh/km × ■8/kWh × 1.10 = ■2,376. ICE at 15 kmpl × ■105/litre = 1500/15 × 105 = ■10,500. EV saves about ■8,000 per month here. Run it with your own numbers — the gap is usually large enough to convince anyone.
Take your annual mileage and calculate annual fuel cost for both vehicles. EV annual cost = annual km × kWh per km × electricity rate × 1.10. ICE annual cost = annual km ÷ kmpl × fuel price per litre. Subtract EV from ICE for savings. For 18,000 km a year, an EV at ■2,500/month saves roughly ■95,000 over a comparable petrol car costing ■10,500/month in fuel. That's enough to cover a few years of insurance, or the price premium on the EV itself in three to five years depending on the cars compared. Plug in your own numbers — they don't lie.
Six numbers cover most of it. From the EV side: annual or monthly mileage, the car's kWh per mile (or per km), your electricity tariff, and a charging-loss factor (use 1.10 if unsure). From the ICE side: same mileage figure, the gas car's MPG (or kmpl), and the current gas price. That's it. If you want extra precision, add public charging share for the EV — say 20% of charging at higher public rates — and a winter consumption penalty. But the six basics will get you within 10% of the truth, which is plenty for decision-making.
A few things can flip the math. If a big chunk of your charging is on expensive public DC fast chargers at ■22-25 per kWh, the cost rises fast. If you're comparing against a small, efficient ICE car doing 22+ kmpl, the savings shrink. If your local gas prices are low or your electricity is unusually expensive (some commercial tariffs run ■12-15 per kWh), the math gets thin. Run the numbers honestly — most negative-savings cases come down to one of these. EVs save the most for high-mileage drivers with cheap home charging and an inefficient ICE comparison.
Yes, if you want a real-world comparison. Gas cars are measured at the pump — every litre you pay for goes into the tank. EVs lose 8-12% between the wall meter and the battery, so the energy you actually drive on is less than what you paid for. Skipping the loss factor makes EVs look slightly better than they really are. Multiply your battery-energy calculation by 1.10 to account for it. The savings are still impressive, but using the wall-meter number makes the case truthful and harder to argue against. Honesty beats optimism in customer conversations.
Public DC fast charging at ■20-25 per kWh can erode EV savings significantly compared to home charging at ■8. Calculate a blended rate based on your charging mix. If you do 80% at home and 20% at public chargers: blended rate = (0.8 × ■8) + (0.2 × ■22) = ■6.4 + ■4.4 = ■10.8 per kWh. That's 35% higher than pure home charging. Run your savings calculation with the blended rate. For frequent road trippers using mostly public charging, EV fuel savings can shrink by half or more compared to home-only owners. Charging mix matters enormously.
Don't compare them directly — they measure different units. Instead, convert both to cost per mile and compare those. EV cost per mile = (kWh per 100 miles ÷ 100) × electricity rate. Gas cost per mile = gas price ÷ MPG. So 30 kWh/100 mi at ■8 is 0.30 × 8 = ■2.40 per mile. A 30 MPG car at ■400/gallon equivalent (■105 per litre × 3.78 litres) = ■400 ÷ 30 = ■13.30 per mile. Now you're comparing rupees to rupees. The EV's '30' looks similar to the ICE's '30' but the costs aren't even close.
Quick formula: EV cost per 100 miles = kWh/100 mi × electricity rate. ICE cost per 100 miles = (100 ÷ MPG) × gas price. Subtract for savings per 100 miles. Example: EV at 30 kWh/100 mi × ■8 = ■240. ICE at 30 MPG = (100/30) × ■400 per gallon ≈ ■1,333. Difference: about ■1,090 saved per 100 miles. Multiply by however many hundred-mile chunks you drive in a year. For an average driver doing 12,000 miles annually, that's roughly ■130,000 in savings. Real money — and the gap usually widens as gas prices rise.
Gas prices are the biggest swing factor in EV savings calculations. When petrol jumps from ■95 to ■110 per litre, an ICE car doing 15 kmpl suddenly costs ■1.00 more per km — adding ■15,000 a year for a 15,000 km driver. Meanwhile EV electricity costs barely budge in the short term. So when fuel prices spike, EV savings widen instantly without you doing anything. The reverse is also true — if gas prices drop, the gap narrows. EV savings are essentially insurance against gasoline price volatility, which is worth real money even before counting the per-km savings.
Set EV cost per mile equal to gas cost per mile and solve for electricity rate. Formula: break-even rate = (gas price ÷ MPG) ÷ kWh per mile. Example: a gas car at ■105/litre × 3.78 litres/gallon = ■397/gallon, doing 25 MPG = ■15.88 per mile in fuel. EV uses 0.30 kWh/mile. Break-even electricity rate = 15.88 ÷ 0.30 = ■52.93 per kWh. So as long as your electricity costs less than ■53 per kWh, the EV is cheaper to fuel. Most home tariffs are well under ■10. The break-even rate shows just how lopsided the math is.
Sources & references
- U.S. Energy Information Administration: Measuring electricity - Defines kW and kWh used in cost math.
- U.S. DOE Energy Saver: Fuel economy in cold weather - Notes real world efficiency impacts.
- U.S. EPA: Fuel economy and EV range testing - Explains fuel economy metrics used for comparisons.
- Schema.org: FAQPage, WebPage, and BreadcrumbList - Structured data definitions used on this page.