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Running-cost comparison

Petrol or gas vs EV cost calculator

Compare the annual energy cost of a petrol car and an electric car over the same distance. Add an optional purchase-price difference to estimate a simple break-even. The result separates running costs from ownership costs and does not assume the EV is cheaper.

UK: miles, MPG UK and pence. US: miles, MPG US and dollars. Europe, Switzerland and Australia: kilometres, L/100 km and local currency. Japan, India and South Korea: kilometres, km/L and local currency.

A running-cost comparison is not a total-cost comparison

The headline result excludes depreciation, insurance, maintenance, tyres, road tax, charger installation and resale value. Those can change the answer, sometimes by more than the energy saving.

Compare the running costs

Your inputs

Changing market resets the example values so the units cannot silently carry over.

mi

Petrol side

MPG UK
p/litre

EV side

mi/kWh

Use a battery-side (dashboard) figure. EPA MPGe-derived efficiency already includes charging losses.

p/kWh
%

The share of grid energy that reaches the battery.

£

EV purchase price minus petrol purchase price. Leave 0 to skip break-even.

ExampleStarting values are illustrative, not current prices. This comparison covers running energy costs only.

Estimated result

Annual running-cost comparison

Estimated annual saving with the EV

£524.72

Petrol £1,318.37 per year vs EV £793.65 per year. The EV is cheaper on these running-cost inputs.

Petrol annual cost

£1,318.37

909.2 litres

EV annual cost

£793.65

3,175 kWh from the grid

Petrol cost per 100 km

£8.19

EV cost per 100 km

£4.93

Petrol cost per mile

£0.132

EV cost per mile

£0.079

Five-year running cost

£6,592 vs £3,968

Petrol vs EV, energy only

Running energy costs only. This does not include purchase price unless you enter a difference, nor depreciation, insurance, maintenance, tyres, road tax, charger installation or resale value. Enter a positive purchase-price difference to estimate break-even; no break-even is shown when the EV does not save on running costs.

How the comparison works

Petrol side

UK:  litres = miles ÷ MPG (UK) × 4.54609
     cost = litres × (pence/litre ÷ 100)
US:  gallons = miles ÷ MPG (US)
     cost = gallons × dollars/gallon
EU/CH/AU: litres = km × (L/100 km) ÷ 100
          cost = litres × local currency/litre
JP/IN/KR: litres = km ÷ (km/L)
          cost = litres × local currency/litre

The same annual distance is used for both sides. The annual figure is not a lifetime cost and does not include servicing or repairs.

EV side

UK/US: battery kWh = miles ÷ (mi/kWh)
EU/CH/AU/JP/IN/KR: battery kWh = km × (kWh/100 km) ÷ 100

grid kWh = battery kWh ÷ charging efficiency
cost = grid kWh × price per kWh

Charging efficiency accounts for energy lost between the meter and the battery. The EV efficiency input is battery-side; EPA MPGe-derived figures already include charging losses, so do not add them twice.

Annual difference = petrol annual cost − EV annual cost. A positive value means the EV is cheaper on the inputs provided. Break-even years = purchase-price difference ÷ annual saving, shown only when both are positive.

Worked examples

Illustrative prices, consumption and charging efficiency. Not current market data.

UK example

10,000 miles · 50 MPG UK · 145p/l · 3.5 mi/kWh · 25p/kWh

£524.72 saved

£1,318 petrol vs £794 EV · break-even 9.5 years on a £5,000 gap

US example

12,000 miles · 30 MPG US · $3.50/gal · 3.5 mi/kWh · 17¢/kWh

US$752.38 saved

$1,400 gas vs $648 EV

EU example

15,000 km · 6.5 L/100 km · €1.75/l · 17 kWh/100 km · €0.35/kWh

€714.58 saved

€1,706 petrol vs €992 EV

What is outside the headline

Purchase price and finance

A price gap can be entered to estimate a simple break-even, but interest, leasing, incentives, taxes and resale value are not modelled.

Depreciation

Depreciation is often the largest single ownership cost. It depends on model, age, mileage, condition and market, and is not predicted here.

Insurance, maintenance and tyres

EV and petrol costs differ by model and region. Tyre wear, servicing, repairs and insurance are excluded from the energy comparison.

Charging hardware and access

Home charger installation, subscriptions, parking and public-charging membership fees can materially change the EV side.

When an EV may not save money

An EV can be more expensive to run on energy alone if public charging is expensive, the vehicle is inefficient, annual mileage is low, or the petrol comparison vehicle is very efficient and fuel is cheap. A high purchase premium also takes longer to recover.

The opposite can be true with low-cost home charging and high annual mileage. The calculator is designed to show the inputs that drive the result rather than assert a universal winner.

Questions

Is an EV cheaper than petrol?
Not automatically. It depends on the price of electricity, where you charge, the efficiency of each vehicle, annual mileage and the petrol price. This calculator shows both annual energy costs and the difference on your inputs. It deliberately does not assume a winner.
How do you calculate EV break-even?
Divide the EV’s purchase-price premium by the annual running-cost saving. If the EV costs £5,000 more and saves £500 a year on energy, the simple energy-only break-even is 10 years. This ignores depreciation, maintenance, financing and resale value.
Should I include home charging losses?
Yes, if you want the cost of electricity purchased from the grid. The car needs battery energy, but the meter supplies more because charging is not 100% efficient. The default of 90% is an example, not a universal value.
Does this work for a plug-in hybrid?
Only as a rough energy comparison. A plug-in hybrid uses both electricity and petrol, often at different rates depending on trip length and charge behaviour. This calculator models one electric side and one petrol side, not a blended PHEV duty cycle.
Why are maintenance and insurance excluded?
They are ownership costs, not energy costs. Including them properly needs model-specific, region-specific data and assumptions about servicing, repairs, insurance and resale. Mixing them into an energy comparison would create a false sense of precision.

Sources

Context for prices and efficiency. Enter your own figures above; these sources are not live quotes.

Page last reviewed: . Formulas are covered by automated tests. Prices are inputs, not live data.

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Need the charging side on its own? Use the EV charging cost calculator.