How this EV vs petrol calculator works
Comparing an electric car with a petrol car by sticker price alone is misleading, and comparing by fuel cost alone flatters the EV. The honest comparison is total cost of ownership (TCO), meaning everything you pay from purchase to resale, plus lifecycle emissions, including the carbon released to manufacture the battery. This calculator does both, year by year, for the period you plan to keep the car.
For each car it adds the purchase price (minus any EV subsidy), energy, maintenance, insurance and road tax for every year, letting electricity and petrol prices grow at their own rates. At the end of the ownership period it credits the resale value, calculated with a constant annual depreciation rate. It then finds two break-even points: the distance at which the EV’s lower running costs repay its higher net fixed costs, and the distance at which the EV’s lower driving emissions repay its higher manufacturing emissions.
The formula
Resale = list price × (1 − depreciation)^years EV energy per km = consumption ÷ (1 − charging loss) × electricity price Break-even km = ΔFixed ÷ (petrol cost/km − EV cost/km)
Lifecycle CO₂ = manufacturing + km × g/km EV manufacturing = body + battery kWh × kg CO₂/kWh Petrol g/km = L/100 km × 23.1 × 1.2 (tailpipe + well-to-tank)
Worked example
With the defaults, you keep the car 8 years and drive 15,000 km a year (120,000 km in total).
The EV costs €40,000 with no subsidy, uses 17 kWh/100 km plus 10% charging losses, and pays €0.28/kWh. Its energy over eight years comes to about €6,800, maintenance €3,600 (€0.03/km), and insurance €7,200. With 14% annual depreciation it is worth about €12,000 at the end. TCO: €45,640, or €0.380 per km.
The petrol car costs €32,000, uses 6.5 L/100 km at €1.75/L, and needs €0.05/km of maintenance, €800/yr insurance and €200/yr road tax. Fuel adds up to about €14,600, maintenance €6,000 and insurance plus tax €8,000. At 13% depreciation it resells for about €10,500. TCO: €50,140, or €0.418 per km.
The EV is therefore about €4,500 cheaper over eight years. Depreciation is the EV’s biggest cost (€28,000 versus €21,500), but it saves around €7,800 on energy and €2,400 on maintenance. Running costs are €8.29 per 100 km for the EV versus €16.38 for petrol, so the EV breaks even at roughly 71,000 km, about 8,900 km a year.
On emissions, the EV starts with 11.5 t of manufacturing CO₂ (7 t body plus 4.5 t for a 60 kWh battery at 75 kg/kWh) versus 7 t for the petrol car. At 300 g/kWh it emits about 57 g/km against 180 g/km well-to-wheel for petrol, repaying the battery after about 36,000 km (2.4 years). Over 120,000 km it emits 18.3 t versus 28.6 t, which is 36% less.
How to read the results
- Saving with the EV (headline) is the TCO difference; negative means the petrol car is cheaper.
- Cost per km puts both cars on the same footing regardless of how long you keep them.
- Break-even distance tells you whether your mileage is high enough for the EV to pay off. If it says “from day one”, the EV is cheaper even before running-cost savings.
- Cost breakdown chart shows where the money goes; depreciation usually dominates for both.
- Cumulative CO₂ chart shows the EV starting higher and crossing the petrol line at the carbon break-even.
Typical values
| Item | Electric car | Petrol car |
|---|---|---|
| Energy use | 14–22 kWh/100 km | 5–8 L/100 km |
| Energy cost per 100 km (home charging / €1.75 L) | €3–6 | €9–14 |
| Maintenance | €0.02–0.04/km | €0.04–0.07/km |
| Manufacturing CO₂ (excl. battery) | 6–9 t | 6–9 t |
| Battery manufacturing | 50–100 kg CO₂/kWh | — |
| Driving CO₂ | 0–170 g/km (grid 0–900 g/kWh) | 150–230 g/km well-to-wheel |
Tips to make the EV pay off sooner
- Charge at home or work. Relying on DC fast charging can double the EV’s energy cost. Check your mix in the EV charging cost calculator.
- Keep the car longer. Most of the EV’s advantage comes from running costs, which accumulate every year.
- Consider a nearly-new EV. Steep early depreciation is paid by the first owner; a two- or three-year-old EV can flip the TCO result.
- Pick the right battery size. A battery larger than you need adds purchase cost, weight and manufacturing CO₂.
- Add solar. Charging from your own solar panels lowers both cost and emissions.
Limitations
Grid intensity is held constant, although most grids are decarbonising, which favours the EV; you can test a lower future value. Depreciation is a single constant rate and does not capture market shocks. Financing costs, parking, tolls, congestion charges, company-car taxation and battery replacement (rare within eight years) are excluded. Petrol emissions use a flat 20% upstream uplift, and the calculator does not model end-of-life recycling credits. Treat the result as a structured comparison, then check local prices and incentives.
Method & assumptions
TCO = purchase − subsidy + Σ (energy + maintenance + insurance + tax) − resale value. Energy cost escalates at the chosen rates. Break-even distance solves (fixed-cost difference) ÷ (petrol cost per km − EV cost per km). Lifecycle CO₂ = manufacturing (body + battery kWh × kg CO₂/kWh for the EV) + km × g/km; carbon break-even is the distance where the EV's extra manufacturing emissions are repaid.
Frequently asked questions
Is an electric car cheaper than a petrol car overall?
How many kilometres before an EV pays off?
How much CO₂ does making an EV battery emit?
After how many km is an EV greener than a petrol car?
Do electric cars depreciate faster?
Are EV maintenance costs really lower?
Sources & references
Embed this calculator
Free for blogs, installers, schools and NGOs. Copy the code below; it updates itself automatically.