Fuel Cost Calculator: Petrol vs Diesel vs CNG vs EV
Compare what the same driving actually costs to run on petrol, diesel, CNG, or electric — broken down by day, week, month, and year. Pick your country for local units and starting prices, then edit any price to match your own pump receipt or electricity bill.
That works out to about 10,950 mi a year. Prices below are indicative defaults (reviewed Aug 2026) — edit any of them to your local price for an exact result.
$0.11 per mi
$0.11 per mi
$0.05 per mi
EV is the cheapest to run for your distance — about $532/year. That is $708 a year cheaper than Diesel ($1,240/year).
| Fuel | Per day | Per week | Per month | Per year |
|---|---|---|---|---|
EVcheapest | $1.46 | $10.23 | $44.32 | $532 |
Petrol | $3.20 | $22.46 | $97.33 | $1,168 |
Diesel | $3.40 | $23.84 | $103 | $1,240 |
Running (fuel/energy) cost only. It excludes purchase price, insurance, servicing, road tax, and battery depreciation — a full “total cost of ownership” needs those too. Everything runs in your browser; no data is sent anywhere.
TL;DR
Running cost comes down to one sum: fuel price ÷ how far that fuel takes you. Enter how much you drive, pick your country, and the calculator converts each fuel into a cost per day, week, month, and year, then ranks them cheapest-first. In most countries the usual order from cheapest to priciest is EV → CNG → diesel → petrol, but the gap depends entirely on your local prices and your car’s efficiency — which is why every number here is editable. This is fuel/energy cost only; it does not include the car’s purchase price, insurance, or servicing.
Typical cost to drive one mile / km, by fuel
Using the indicative August 2026 default prices built into the calculator, here is roughly what each fuel costs per unit of distance in three representative markets. US and UK figures are per mile; India is per kilometre — so compare down each column, not across.
| Fuel | US ($/mi) | UK (£/mi) | India (₹/km) |
|---|---|---|---|
| Petrol | $0.11 | £0.14 | ₹6.25 |
| Diesel | $0.11 | £0.13 | ₹4.50 |
| CNG | $0.08 | — | ₹3.27 |
| Electric (EV) | $0.05 | £0.08 | ₹1.00 |
CNG passenger cars are uncommon in the UK, so no representative figure is shown. Values assume typical efficiencies (a ~30 MPG petrol car, ~45 UK-MPG, a 16 km/l petrol car in India) and home EV charging. Public fast-charging is far more expensive — see the FAQ.
A year of driving: worked example (India, 15,000 km)
Small per-km differences turn into large annual gaps. Here is the same 15,000 km a year priced across all four fuels at the default Indian prices, so the spread is impossible to miss.
| Fuel | Per month | Per year | vs Petrol |
|---|---|---|---|
| Petrol | ₹7,813 | ₹93,750 | — |
| Diesel | ₹5,625 | ₹67,500 | −₹26,250 |
| CNG | ₹4,087 | ₹49,038 | −₹44,712 |
| Electric (EV) | ₹1,250 | ₹15,000 | −₹78,750 |
At these prices, switching from petrol to home-charged EV saves about ₹78,750 a year in fuel alone — but an EV’s higher purchase price and a CNG kit’s upfront cost have to be weighed against these savings. Change the numbers in the calculator to fit your own car.
How the calculator works
Every fuel is reduced to a single figure — cost per unit of distance — using the same idea:
- Petrol & diesel — price per litre or gallon, divided by fuel economy (km/l or MPG).
- CNG — price per kg (or per GGE in the US), divided by km/kg (or mi/GGE).
- Electric — electricity price per kWh, divided by the car’s range per kWh (km/kWh or mi/kWh).
- Your annual distance is worked out from what you enter, then split into daily, weekly, and monthly costs.
One quirk worth knowing: the UK prices fuel per litre but still quotes economy in miles per imperial gallon (4.546 litres). The calculator handles that conversion for you, so a UK MPG figure and a per-litre pump price combine correctly.
What this does not include
This is a running-costcomparison — the cost of the fuel or electricity to move the car, and nothing else. A complete “total cost of ownership” decision also has to weigh the vehicle’s purchase price (EVs and CNG cars usually cost more upfront), insurance, servicing and maintenance, road tax or registration, and resale value and battery degradation for EVs. A fuel that’s cheaper to run can still be more expensive overall if it costs much more to buy — use this tool for the fuel half of that decision, and pair it with the total price difference to see the real break-even.
Don’t know your car’s efficiency? Start here
The most accurate number is your own — track a few tankfuls or charges — but if you just want a realistic starting point, these are typical real-world figures by vehicle type. Real-world economy usually runs 10–20% below the official sticker figure, so these are deliberately conservative.
| Vehicle | US MPG | UK MPG | km/L |
|---|---|---|---|
| Small hatchback (petrol) | 35 | 45 | 18 |
| Mid-size sedan (petrol) | 30 | 40 | 15 |
| SUV (petrol) | 24 | 32 | 11 |
| Sedan (diesel) | 38 | 55 | 22 |
| SUV (diesel) | 28 | 40 | 16 |
For electric cars, efficiency is measured as distance per kWh. Typical real-world figures:
| EV type | mi/kWh | km/kWh |
|---|---|---|
| Small EV (city car) | 4.0 | 6.5 |
| Mid-size EV | 3.5 | 5.6 |
| Large EV / electric SUV | 2.7 | 4.3 |
When does an EV’s fuel saving pay back its higher price?
A cheaper-to-run car can still cost more overall if it’s pricier to buy. The break-even is simple once you know your annual fuel saving from the calculator above:
Two very different examples show why the answer depends on where you live. In the US, if an EV costs $8,000 more than the petrol equivalent and saves about $700 a year in fuel, that’s a roughly 11-year payback on fuel alone. In India, where petrol is expensive relative to home electricity, an EV premium of ₹4 lakh against a ₹78,000-a-year fuel saving pays back in closer to 5 years.
Two things shift the break-even in the EV’s favour that this simple sum ignores: EVs are usually cheaper to service (no oil changes, fewer moving parts, less brake wear from regenerative braking), and many countries offer purchase subsidies or tax breaks that cut the upfront gap. High-mileage drivers reach break-even fastest, because the saving is per kilometre — the more you drive, the sooner it pays.
Frequently asked questions
Is an electric car really cheaper to run than petrol?
In most cases, yes — usually dramatically so when you charge at home, because electricity per kWh buys far more distance than petrol per litre. At the default prices above, an EV runs at roughly a third to a fifth of the per-mile cost of petrol. The advantage shrinks if you rely on expensive public rapid chargers or if your local electricity is unusually pricey, so enter your real charging cost to be sure.
Is diesel or petrol cheaper to run?
Diesel usually wins on running cost because diesel engines are more efficient, so a diesel car travels further per litre — even where diesel costs more at the pump than petrol. That efficiency edge matters most for high-mileage drivers; for low annual distances the higher purchase price and servicing of a diesel often outweigh the fuel saving.
Is CNG cheaper than petrol?
Where CNG is widely available — notably India — it is typically the cheapest liquid/gas fuel to run, often 40–50% below petrol per kilometre, which is why CNG is popular for taxis and high-use cars there. The catch is a limited refuelling network, some boot space lost to the tank, and the upfront cost of the CNG kit. It is uncommon for passenger cars in the US, UK, Canada, and Australia.
How do I calculate cost per mile or per km?
Divide the fuel price by the distance one unit of that fuel takes you. For a petrol car doing 30 MPG at $3.20 a gallon, that’s $3.20 ÷ 30 = about $0.11 per mile. For an EV at $0.17/kWh doing 3.5 miles per kWh, it’s $0.17 ÷ 3.5 = about $0.05 per mile. The calculator does this for all four fuels at once and multiplies by your annual distance.
Does the EV cost include public charging?
The default electricity price assumes home charging, which is the cheapest way to charge. Public rapid chargers can cost two to four times as much per kWh, which narrows or even erases the EV advantage on long trips. If you charge mostly in public, replace the electricity price with your charger’s rate to see the honest comparison.
Are these fuel prices live and accurate?
No — they are indicative starting figures reviewed in August 2026, seeded from published national averages (GlobalPetrolPrices, EIA, Eurostat). Fuel and electricity prices change week to week and vary by city and supplier, so the tool lets you overwrite every price. For an exact result, type in the numbers from your own latest pump receipt and electricity bill.