Comparing an electric car to a petrol car by “tank versus charge” doesn’t really work – the containers are different sizes and the fuel is priced completely differently. The fair comparison is cost per 100 kilometres (or per 100 miles), using your own local energy and fuel prices, not a marketing headline. Once you know your own consumption figures, run them through the CalcRange Fuel Cost Calculator and compare like for like.
Key Takeaways
- Compare cost per distance (per 100 km or per 100 miles), not cost per tank or per full charge, since capacities differ.
- EV cost per distance = (kWh consumed per 100 km) x (electricity price per kWh). Petrol cost per distance = (litres per 100 km) x (fuel price per litre).
- In a typical illustrative scenario, an EV can cost roughly a quarter of the per-distance cost of an equivalent petrol car – but this depends entirely on local energy and fuel prices.
- Home charging is usually far cheaper per kWh than public fast charging, which can sometimes approach petrol cost per distance.
- EVs generally have lower routine maintenance costs but can have different costs elsewhere, like tire wear and eventual battery-related expenses.
Compare by Distance, Not by Fill-Up
A petrol tank and an EV battery have no meaningful common unit to compare directly – one measures litres, the other kilowatt-hours, and their capacities vary hugely by vehicle. The comparison that actually means something is cost per unit of distance travelled: how much does it cost to drive 100 kilometres (or 100 miles) in each vehicle, using your own real-world consumption figures and local prices, not a manufacturer’s best-case efficiency rating.
The Two Formulas
EV cost per 100 km = (kWh consumed per 100 km) × (electricity price per kWh). Petrol cost per 100 km = (litres consumed per 100 km) × (fuel price per litre). Both formulas boil down to the same structure: consumption rate multiplied by the price of the energy source, giving a directly comparable cost-per-distance figure regardless of how differently the two fuel types are measured or sold.
An Illustrative Worked Example
Using round, illustrative figures rather than any specific country’s actual prices, since these vary enormously and change often: an EV consuming 18 kWh per 100 km at an illustrative $0.15 per kWh costs $2.70 per 100 km. A petrol car consuming 7 litres per 100 km at an illustrative $1.50 per litre costs $10.50 per 100 km. In this illustrative scenario, the EV costs roughly a quarter of the petrol car’s per-distance fuel cost – but this ratio shifts substantially depending on your actual local electricity and fuel prices, which is exactly why plugging in your own numbers matters more than any generic comparison.
| Vehicle Type | Consumption | Illustrative Price | Cost per 100 km |
|---|---|---|---|
| Electric | 18 kWh/100 km | $0.15/kWh | $2.70 |
| Petrol | 7 L/100 km | $1.50/L | $10.50 |
Home Charging vs Public Fast Charging
Where an EV charges changes the comparison substantially. Charging at home overnight is typically priced far below public DC fast-charging rates, which carry a premium for speed and convenience. In some markets, relying heavily on public fast charging can push per-distance cost close to, or in some cases above, petrol cost per distance – meaning “EVs are always cheaper to run” isn’t a universal truth, it depends heavily on where the charging actually happens, not just the vehicle type.
Plug In Your Own Local Prices
Use the CalcRange Fuel Cost Calculator with your actual local fuel or electricity price and your vehicle’s real-world consumption to get a comparison that means something for your situation, rather than relying on a generic figure. Our guide on how to improve fuel efficiency covers habits that lower the consumption side of the equation for either vehicle type.
Costs Beyond Fuel and Electricity
A fair full comparison looks past just the energy cost. EVs generally have lower routine maintenance costs, since they have fewer moving parts in the drivetrain and don’t need oil changes, but they can have other costs that run differently: tires sometimes wear faster due to instant torque and the added weight of the battery pack, and long-term battery degradation or eventual replacement is a cost petrol vehicles simply don’t have an equivalent for. Neither side of the comparison is free of trade-offs once you look past the headline fuel-cost-per-distance figure.
Frequently Asked Questions
How do you fairly compare EV and petrol running costs?
Compare cost per 100 km or per 100 miles using your own local energy and fuel prices and real-world consumption figures, rather than comparing a full tank to a full charge, since their capacities aren’t comparable units.
Is an EV always cheaper to run than a petrol car?
Not universally – it depends heavily on local electricity and fuel prices and where the EV is charged. Home charging is typically much cheaper than public fast charging, which can sometimes approach or exceed petrol cost per distance.
What’s the formula for comparing EV and petrol cost per distance?
EV: kWh consumed per 100 km times electricity price per kWh. Petrol: litres consumed per 100 km times fuel price per litre. Both give a directly comparable cost-per-distance figure.
Why is public fast charging more expensive than home charging?
Public fast chargers typically carry a premium for speed and convenience, while home charging, especially overnight, is usually priced at standard residential electricity rates, which are generally lower.
Do EVs have lower maintenance costs than petrol cars?
Generally, for routine maintenance, yes – fewer moving parts and no oil changes reduce regular servicing costs, though EVs can have other cost considerations like tire wear and long-term battery-related expenses.
Does the EV cost advantage apply everywhere in the world?
Not uniformly – the size of the cost advantage, or whether one exists at all, depends heavily on local electricity and fuel prices, which vary substantially by country and even by region within a country.
The Bottom Line
Comparing EV and petrol running costs fairly means comparing cost per distance using your own real prices and consumption, not a headline claim from either side. In many scenarios EVs come out meaningfully cheaper per distance, especially when charged at home, but the gap depends entirely on local prices and charging habits, not a fixed universal ratio.
Financial disclaimer: This article is for general educational purposes and uses illustrative, not current or location-specific, prices. Actual costs vary significantly by region, vehicle, and energy market. Use your own local prices when making a purchasing decision.
Last reviewed: August 2026