How does the petrol vs diesel calculator compare costs?

It divides the same distance by each vehicle's entered km/L efficiency, multiplies the resulting litres by the matching fuel price, and compares those fuel costs for the selected period.

Does diesel always cost less to run?

No. The result depends on real fuel efficiency, local petrol and diesel prices, and distance travelled. Diesel may use fewer litres yet still cost more when its price or efficiency difference makes the total higher.

What mileage figures should I enter?

Use real km/L measured under comparable routes, loads, traffic, and driving conditions. Comparing an advertised highway figure with a city-driving figure would produce a misleading result.

How is the diesel break-even point calculated?

When both vehicle prices are entered, the calculator divides the positive diesel purchase-price premium by annualized diesel fuel savings. It shows no break-even when diesel is not dearer to buy or does not save fuel cost.

Does the comparison include maintenance and resale value?

No. It compares fuel expense and an optional purchase-price difference only. Servicing, repairs, taxes, insurance, financing, emissions equipment, depreciation, and resale value are excluded.

Can I compare two different vehicles?

Yes, if you enter the real efficiency and purchase price for each specific vehicle. For a fair comparison, use the same distance period and similar operating conditions.

Can I use any currency?

Yes. Enter both fuel and vehicle prices in the same currency and type its code as the result label. The calculator does not fetch prices or convert exchange rates.

Fuel comparison

Petrol vs Diesel Calculator

Compare petrol and diesel fuel consumption, cost per period, annualized difference, and an optional purchase-price break-even. Every price and efficiency assumption comes from you.

Bike, scooter, car, or truck
Privacy-first
Annual forecast included

Calculate Your Petrol vs Diesel Cost

Metric inputs · fuel-only comparison · optional purchase-price break-even

Distance travelledKilometres in the selected periodDistance periodPetrol efficiency (km/L)Diesel efficiency (km/L)Petrol price per litreDiesel price per litreCurrency code

Petrol vehicle price (optional)Diesel vehicle price (optional)

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

Formula and example

How the Petrol vs Diesel Calculator Works

Petrol litres equals distance divided by petrol km/L; diesel litres equals distance divided by diesel km/L. Fuel cost equals litres multiplied by price per litre. Annual multipliers are 365 for daily distance, 52 for weekly distance, 12 for monthly distance, and 1 for annual distance.

Comparison formula

Difference = (Distance ÷ km/L) × Price

For example, 1,000 km/month; petrol vehicle 12 km/L; diesel vehicle 16 km/L. Enter both current local fuel prices.

Petrol required

1,000 ÷ 12

83.33 L

Diesel required

1,000 ÷ 16

62.5 L

Monthly difference

higher − lower

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 when weighing petrol against diesel 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 Diesel Running Cost

Enter the distance driven in a day, week, month, or year. Enter each vehicle's real fuel efficiency in kilometres per litre. Enter local petrol and diesel prices per litre in the same currency. Optionally enter both purchase prices to estimate when diesel fuel savings recover a higher diesel price.

Use equivalent vehicles and operating conditions. This tool answers a fuel-cost question; it does not decide which engine, model, or powertrain is best for every owner.

01Use case

Fuel comparison

Compare litres used, fuel cost, the difference, and the annualized result.

02Use case

Break-even check

Enter both purchase prices to see when fuel savings recover the premium.

03Use case

Price update

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

Fuel comparison guide

Fuel Comparison Guide

Enter comparable efficiencies and prices, understand when break-even is meaningful, and know what the comparison excludes.

Mileage, fuel price, distance, and driving conditions

Real-world fuel efficiency

Engine size, vehicle mass, transmission, payload, towing, tyre pressure, traffic, idling, gradients, speed, air conditioning, trip length, and driving style can change consumption. Use measured petrol and diesel mileage from comparable use rather than mixing unrelated test conditions.

Local fuel price

Petrol and diesel prices can move independently. Enter current prices from the same market and update the comparison when prices change. Currency is a label only; no live fuel-price feed or exchange conversion is used.

Distance and period

Annualizing a representative month can support budgeting, but seasonal mileage may differ. Enter annual distance directly when work patterns, holidays, weather, or long journeys make a typical month unreliable.

When a fuel-savings break-even is meaningful

A break-even estimate needs a positive diesel purchase-price premium and positive annual diesel fuel savings. If either purchase price is missing, the calculator deliberately omits break-even. If diesel costs less to buy, or petrol has the lower fuel bill, dividing a premium by savings would not describe a valid diesel payback period.

Even a valid fuel-only break-even is not total cost of ownership. Compare user-supplied servicing, repairs, financing, registration, tax, insurance, depreciation, resale value, and any emissions-system costs separately before making a purchase decision.

Methodology, Accuracy and Assumptions

This page covers petrol, gasoline, diesel, fuel efficiency, km/L, litres, distance, pump price, running cost, annual fuel expense, purchase-price premium, savings, and payback period. Petrol and gasoline are treated as the same fuel label; diesel remains a separate input.

It does not estimate CNG or electric charging, fleet dispatch, commercial profitability, maintenance schedules, emissions, or vehicle resale. For a single petrol journey use the trip petrol calculator; for ordinary petrol spending use the general petrol calculator. This boundary avoids duplicating the intent of those tools.

The calculator uses the visible metric formulas without external data. Results depend entirely on the entered distance, km/L values, prices, period, currency, and optional vehicle prices. Inputs must be positive; zero and negative values are rejected.

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

FAQ

Petrol vs diesel calculator questions

Answers about efficiency, fuel prices, running cost, and break-even assumptions.

More calculators

Related Fuel Calculators For Every Vehicle, Trip, and Driver

The universal calculator handles most cases, while dedicated tools cover specific vehicles, budgets, comparisons, trips, and professional driving needs.