How does the petrol vs CNG calculator work?

It divides distance by petrol efficiency in km/L and CNG efficiency in km/kg, then multiplies each fuel amount by its matching local price. It compares total cost and cost per kilometre.

Can I convert litres of petrol directly to kilograms of CNG?

No. A litre is a volume unit and a kilogram is a mass unit. Petrol and CNG also have different energy content and storage conditions, so the calculator keeps each fuel in its own unit.

What CNG mileage should I enter?

Use measured km/kg from the vehicle under representative traffic, load, route, and air-conditioning conditions. Do not reuse a petrol km/L figure as if it were CNG km/kg.

Is CNG always cheaper than petrol?

No. The answer depends on each fuel's real efficiency and local price. Availability, conversion costs, maintenance, tank inspection, and reduced cargo space may also matter but are outside this fuel-only result.

Does this include the cost of a CNG conversion kit?

No. It compares fuel expense only. Installation, certification, inspection, servicing, repairs, finance, depreciation, and resale value are not included.

Can I use any currency?

Yes. Enter both prices in the same currency and use its code as the result label. The calculator does not retrieve live prices or exchange rates.

Why can actual CNG cost differ from the estimate?

Traffic, idling, payload, tyre pressure, engine condition, tuning, driving style, filling pressure, station measurement, and route gradients can change real consumption.

Fuel comparison

Petrol vs CNG Calculator

Compare a petrol vehicle with a compressed natural gas vehicle using the same distance and your real-world efficiency and pump-price inputs. See separate fuel quantities, total expense, and cost per kilometre.

Bike, scooter, car, or truck
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140+ currencies preset

Calculate Your Petrol vs CNG Cost

Petrol in litres · CNG in kilograms · your local prices

Distance travelled (km)Currency codePetrol efficiency (km/L)Petrol price per litreCNG efficiency (km/kg)CNG price per kilogram

Unit note: litres and kilograms measure different quantities and are not converted into each other. Each fuel is calculated from its own efficiency and price.

Enter values greater than zero for distance, both efficiencies, and both fuel prices.

Formula and example

How the Petrol vs CNG Calculator Works

Petrol litres equals distance divided by petrol km/L; CNG kilograms equals distance divided by CNG km/kg. Each fuel amount is multiplied by its matching local price. Calculations retain full precision and round displayed results.

Comparison formula

Cost = (Distance ÷ Efficiency) × Price

For example, 1,000 km; petrol efficiency 12 km/L; CNG efficiency 18 km/kg. Enter both local fuel prices.

Petrol required

1,000 ÷ 12

83.33 L

CNG required

1,000 ÷ 18

55.56 kg

Difference

petrol − CNG

Your saving

Illustrative reference

Vehicle Mileage Calculator Example

Petrol economy ranges and the daily cost they produce across common vehicle types. Use them as a petrol reference point before comparing petrol with CNG above.

Currency

Detecting your currency — pick one manually if you prefer.

Petrol price per litre

per litre

Use the current pump price in your currency. It is not fetched automatically.

Vehicle

km/L

Vehicle	Fuel economy	Fuel / day	Cost / day	Cost / month
Light commuter bike	55–65	0.50 L	—	—
Standard commuter bike	45–50	0.63 L	—	—
Mid-size commuter bike	45–50	0.63 L	—	—
Sport commuter bike	40–45	0.71 L	—	—
Larger commuter bike	38–42	0.75 L	—	—
Light city scooter	50–55	0.57 L	—	—
Comfort scooter	42–48	0.67 L	—	—
Urban scooter	48–52	0.60 L	—	—
Compact hatchback	18–22	1.50 L	—	—
Small family car	14–17	1.94 L	—	—
Mid-size sedan	12–15	2.22 L	—	—
Compact sedan	13–16	2.07 L	—	—
Large sedan	11–13	2.50 L	—	—
Large SUV	8–10	3.33 L	—	—
Pickup truck	9–12	2.86 L	—	—
Compact SUV	12–14	2.31 L	—	—

Based on a 30 km trip using the midpoint of each economy range. Add a petrol price to see daily and monthly cost.

How to use it

Calculate Petrol vs CNG Running Cost

Enter the distance travelled in kilometres. Enter petrol mileage in km/L and its price per litre. Enter CNG mileage in km/kg and its price per kilogram. Use the same currency and comparable driving conditions.

Use observed efficiency from the specific petrol and CNG vehicles or operating modes being compared. The tool does not assume that either fuel is cheaper.

01Use case

Fuel comparison

Compare fuel required, total cost, cost per kilometre, and the difference.

02Use case

Measured inputs

Use observed km/L and km/kg from comparable driving conditions.

03Use case

Price update

Re-enter both local prices from the same market whenever they change.

Fuel comparison guide

Fuel Comparison Guide

Enter comparable mileage and prices, and understand what this fuel-only comparison excludes.

Mileage, price, vehicle, and route factors

Petrol mileage and CNG mileage

Petrol efficiency is expressed as kilometres per litre, while CNG efficiency is commonly expressed as kilometres per kilogram. Engine tuning, conversion quality, vehicle mass, cylinder load, traffic, gradients, speed, idling, tyre pressure, and air-conditioning use can alter both figures.

Local pump prices

Enter current petrol per-litre and CNG per-kilogram prices from the same market. CNG availability, filling pressure, and station measurements may vary. Currency is a label only, with no exchange-rate conversion.

Comparable conditions

Compare the same distance and similar routes, payloads, seasons, and driving styles. Mixing a petrol highway test with a CNG city average would weaken the comparison.

Methodology, Accuracy and Assumptions

This calculator covers petrol, gasoline, CNG, compressed natural gas, km/L, km/kg, litres, kilograms, distance, pump price, fuel required, running cost, and cost per kilometre. It excludes conversion-kit purchase and installation, cylinder inspection, certification, maintenance, repairs, insurance, financing, depreciation, resale, emissions, range, refuelling time, and cargo-space effects.

It provides a neutral cost estimate, not installation, maintenance, or fuel-storage advice. Follow the vehicle manufacturer's instructions and applicable rules, and use qualified professionals for CNG system work.

For diesel comparison use the petrol vs diesel calculator. For a single petrol journey use the trip petrol calculator. These boundaries avoid competing with general mileage, trip, and ownership-cost pages.

The calculator uses only the visible formulas and user-entered distance, efficiency, price, and currency. Positive values are required. It does not fetch vehicle specifications, fuel prices, conversion factors, or exchange rates.

Read the shared calculation methodology and petrol expense formula guide. Last reviewed: 17 September 2026.

FAQ

Petrol vs CNG calculator questions

Answers about litres, kilograms, mileage, fuel prices, running cost, and limitations.

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