EV vs Petrol Cost Calculator

An electric car costs less to run when a kWh of electricity takes it further for less money than a litre of fuel does. The fair way to compare is cost per km (or per mile) for each car, then multiply by how far you drive. At home you pay for the energy lost while charging too. Public chargers usually bill the energy they put into the car, but often at two or three times the home price. Over the years you keep a car, its price, servicing, insurance, tax and what it is worth when you sell matter as much as fuel, so Advanced mode adds them all up.

The formula

km a year = distance × times a year (a day: 365 × days a week ÷ 7)
petrol cost per km = litres per 100 km ÷ 100 × price per litre
price per kWh paid = home share × home price ÷ (1 − losses) + public share × public price
electric cost per km = kWh per 100 km ÷ 100 × price per kWh paid
cost a year = cost per km × km a year
saving a year = petrol cost a year − electric cost a year
petrol CO2 = litres × 2.31 kg (diesel 2.68 kg)
electric CO2 = kWh into the battery ÷ (1 − losses) × grid kg per kWh
net cost after N years = price − incentive + charger + yearly costs + interest − what it’s worth then
worth after t years = price × (resale % ÷ 100)^(t ÷ N)
simple payback = extra upfront cost ÷ (yearly costs of petrol car − yearly costs of electric car)

Worked example

With the starting inputs (shown in US dollars; they follow your currency) you drive 15,000 km a year. The petrol car uses 7 L/100 km and fuel costs $1.00 a litre, so it burns 15,000 × 7 ÷ 100 = 1,050 litres and costs 0.07 × 1.00 = $0.070 a km, or $1,050.00 a year.

The electric car uses 17 kWh/100 km, so 15,000 × 17 ÷ 100 = 2,550 kWh goes into the battery. Simple mode assumes you charge at home at $0.17 a kWh and lose 10% while charging, so you pay for 2,550 ÷ 0.9 = 2,833.33 kWh: 2,833.33 × 0.17 = $481.67 a year, or 0.17 × 0.17 ÷ 0.9 = $0.032 a km. The electric car saves 1,050.00 − 481.67 = $568.33 a year ($47.36 a month), and is 1,050 ÷ 481.67 = 2.2 times cheaper to run.

In Advanced mode the starting mix is 80% at home and 20% at a public charger at $0.45. You then pay 0.8 × 0.17 ÷ 0.9 + 0.2 × 0.45 = 0.15111 + 0.09 = $0.24111 for each kWh in the battery, so a year costs 2,550 × 0.24111 = $614.83 and the saving is $435.17. Home electricity would have to reach about $0.36 a kWh before the two cars cost the same to run.

CO2

Burning a litre of petrol gives off about 2.31 kg of CO2 (diesel about 2.68 kg), so 1,050 litres is 1,050 × 2.31 = 2,425.5 kg, about 2.4 tonnes a year. The electric car draws 2,550 ÷ 0.9 = 2,833.33 kWh from the grid; at a rough world-average 0.45 kg per kWh that is 2,833.33 × 0.45 = 1,275 kg. Change the grid figure to match your country: a low-carbon grid makes the electric car far cleaner, a coal-heavy grid narrows the gap. These are tailpipe and power-station figures only; making the car and its battery adds more, which is not counted here.

Total cost and break-even

Starting values, kept for 8 years, paid in cash: the petrol car costs $25,000 and $900 servicing + $1,500 insurance a year, so with fuel its yearly costs are 1,050 + 2,400 = $3,450. The electric car costs $30,000 plus an $800 home charger, and 614.83 + 450 + 1,700 = $2,764.83 a year. It costs 30,800 − 25,000 = $5,800 more up front and saves 3,450 − 2,764.83 = $685.17 a year, so the price gap is paid back in 5,800 ÷ 685.17 = 8.5 years.

Resale changes the picture. After 8 years the petrol car is worth 40% of its price ($10,000) and the electric car 35% ($10,500). The petrol car’s total cost is 25,000 + 8 × 3,450 − 10,000 = $42,600; the electric car’s is 30,800 + 8 × 2,764.83 − 10,500 = $42,418.67, so it saves $181.33 overall. Counting what each car is worth year by year (losing the same share of its value each year), the electric car’s net cost drops below the petrol car’s after about 7.6 years, the break-even point.

With a loan, both cars use the same down payment, rate and term. At 20% down, 7% and 5 years, the petrol car’s loan costs $3,761.44 in interest and the electric car’s $4,513.73, because it borrows more.

Things that change the answer

• Where you charge. Home charging, especially on a night rate, gives the biggest saving. Mostly public rapid charging can cost as much as petrol.
• Incentives. Grants, tax credits, lower road tax or free parking differ by country and change often, so none are built in. Type in what applies to you.
• Insurance and resale. Electric cars can cost more to insure and may lose value faster or slower depending on the model and market. Use quotes and local used-car prices if you can.
• Servicing. Electric cars have no oil, spark plugs or exhaust, and brakes wear less, so servicing is usually cheaper. Tyres can wear a little faster because the cars are heavier.
• Battery. Most makers give a battery warranty of around 8 years. A replacement out of warranty is expensive but uncommon; add one if you plan to keep the car a long time.

Related calculators

Work out your real fuel economy with the fuel economy calculator, the cost of one trip with the fuel cost calculator, what charging adds to your power bill with the electricity cost calculator, and monthly payments with the car loan calculator.

Unit conversions are exact (1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L; MPGe uses the US EPA’s 33.7 kWh per gallon). Starting prices, car prices and yearly costs are examples to show how it works, not real prices for any car or country. CO2 figures are typical estimates. Checked 10 October 2026.