Fuel Efficiency Calculator

Enter the distance you drove and the fuel you used to calculate real-world fuel efficiency in km/L, L/100km, MPG (UK), and MPG (US).

Fuel Efficiency Results

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km/L — kilometres per litre
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L/100km
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MPG (UK)
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MPG (US)
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Distance: -- / --
Fuel used: --
Formula: --

About This Calculator

What it calculates
Real-world fuel efficiency from distance driven and fuel consumed.
Inputs required
Distance driven (km or miles), fuel consumed (litres, UK gallons, or US gallons)
Outputs
km/L, L/100km, MPG (UK), MPG (US), efficiency rating
Formula
km/L = Distance (km) ÷ Fuel (litres); L/100km = 100 ÷ km/L
Last updated

How to Measure Real-World Fuel Efficiency

Official fuel efficiency ratings from manufacturers (ARAI in India, WLTP in Europe) are measured under controlled test conditions and are typically 10–25% higher than what you’ll see in real driving. The most accurate way to measure your own car’s efficiency is the fill-up method:

  1. Fill the tank completely at the pump.
  2. Reset the trip odometer to zero.
  3. Drive your normal routes (at least 200–300 km for a reliable sample).
  4. Refill the tank to the brim. The litres added = fuel consumed.
  5. Enter the distance (trip meter reading) and litres added into this calculator.

Repeat this process over several tanks and average the results for the most reliable long-term efficiency figure.

Fuel Efficiency Formulas

km/L = Distance (km) ÷ Fuel (litres)
L/100km = 100 ÷ km/L
MPG (UK) = km/L × 2.82481
MPG (US) = km/L × 2.35215

Unit conversion factors used:

  • 1 mile = 1.60934 km
  • 1 UK gallon = 4.54609 litres
  • 1 US gallon = 3.78541 litres
  • UK and US MPG differ because they use different gallon sizes — UK MPG is always about 20% higher than US MPG for the same vehicle.

Worked Example

Post-highway-drive fuel check

Distance driven: 400 km

Fuel added at refuel: 30 litres

km/L = 400 ÷ 30 = 13.33 km/L

L/100km = 100 ÷ 13.33 = 7.50 L/100km

MPG (UK) = 13.33 × 2.825 = 37.6 MPG

MPG (US) = 13.33 × 2.352 = 31.4 MPG

Rating: Average for a mid-size petrol car.

City driving check

Distance driven: 150 km (city traffic)

Fuel used: 18 litres

km/L = 150 ÷ 18 = 8.33 km/L

L/100km = 100 ÷ 8.33 = 12.0 L/100km

This is expected — city mileage is typically 15–25% lower than highway mileage for the same vehicle.

Fuel Efficiency Benchmarks

Use this table to compare your calculated efficiency against typical vehicles. All figures are approximate real-world values.

Vehicle TypeTypical km/LL/100kmMPG (UK)Rating
Small petrol hatchback (city)14–185.6–7.140–51Good
Petrol sedan (mixed)11–156.7–9.131–42Average–Good
Petrol SUV (mixed)8–128.3–12.523–34Below Average–Average
Diesel sedan (mixed)14–185.6–7.140–51Good
Diesel SUV (mixed)10–147.1–10.028–40Average
Large petrol SUV / van5–911.1–20.014–25Below Average
CNG car (km/kg as proxy)20–283.6–5.0—Excellent (low cost)

Common Use Cases

  • Verify your car’s mileage — Compare your real-world efficiency against the manufacturer’s claimed ARAI or WLTP figure to see how much you’re losing to real conditions.
  • Before and after a service — Calculate efficiency before and after a tune-up, air filter change, or tyre inflation to quantify the improvement.
  • Compare city vs highway driving — Measure a tank of pure city driving vs a highway trip to understand the difference.
  • Used car evaluation — Ask the seller to let you calculate a real fill-up cycle to verify their claimed mileage before buying.
  • Fleet management — Track efficiency per vehicle per month to identify poorly performing vehicles that need servicing.
  • Petrol vs diesel decision — Know your current efficiency to plug into the Fuel Cost Calculator for an accurate side-by-side monthly cost comparison.

Frequently Asked Questions

Fill your tank, drive normally, then refuel. Fuel efficiency = distance driven ÷ litres added at refuel. For example, if you drove 400 km and refuelled with 30 litres, your efficiency is 400 ÷ 30 = 13.3 km/L. Enter these two numbers in the calculator to get results in all units instantly.
In India, a good real-world efficiency for a petrol hatchback is 14–18 km/L; for a petrol sedan, 11–15 km/L; for a petrol SUV, 8–12 km/L. Diesel cars are typically 15–20% more efficient. City mileage is 10–25% lower than highway. This calculator shows a Good / Average / Below Average rating based on general benchmarks.
km/L tells you how far you travel per litre — higher is better. L/100km tells you how much fuel you need per 100 km — lower is better. To convert: L/100km = 100 ÷ km/L. For example, 13.3 km/L = 7.52 L/100km. Indian vehicles are rated in km/L; European vehicles use L/100km.
To convert km/L to UK MPG, multiply by 2.825. To convert to US MPG, multiply by 2.352. For example, 13.3 km/L = 37.6 MPG (UK) = 31.3 MPG (US). UK and US gallons are different sizes — UK gallon = 4.546 L, US gallon = 3.785 L — which is why UK MPG is always higher than US MPG for the same vehicle.
Official ARAI and WLTP ratings are measured under controlled test conditions — steady speeds, optimal temperature, no AC, minimal load. Real-world mileage is typically 10–25% lower due to city traffic, air conditioning, cold starts, varying speeds, tyre pressure, and vehicle load. This calculator helps you track your actual mileage to compare trips and spot issues.
Key improvements: keep tyre pressure at the recommended PSI (under-inflation costs 3–5% mileage), service the engine regularly (air filter, spark plugs, fuel injectors), drive at steady speeds (60–80 km/h is optimal for most cars), avoid hard acceleration and braking, reduce AC use in city traffic, remove roof racks when not needed, and avoid idling for more than 1 minute.
Typical ARAI ratings for popular Indian cars: Maruti Alto/S-Presso 22–24 km/L, Maruti Swift (petrol) 21–23 km/L, Hyundai i20 (petrol) 19–20 km/L, Honda City (petrol) 17–18 km/L, Kia Seltos (petrol) 15–16 km/L, Toyota Fortuner (diesel) 14–15 km/L. Real-world figures are 10–20% lower than official ratings.
Yes for diesel — enter km driven and diesel litres consumed for accurate L/100km and km/L. For CNG, enter km driven and CNG kg used (treating kg as litres) for a relative efficiency figure. For electric vehicles, efficiency is measured in km/kWh or Wh/km — a different metric this calculator doesn’t cover.

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Important Notes

Results are based on the distance and fuel figures you enter. For the most accurate measurement, use the fill-up method over a full tank (at least 200–300 km). Short-trip measurements are less reliable because cold-start inefficiency is a larger proportion of total fuel used.

Official ratings (ARAI, WLTP, EPA) should not be used as a direct comparison — they use test cycles designed for regulatory purposes, not real-world conditions.

Results are for informational purposes only. Real-world fuel efficiency varies based on driving conditions, vehicle condition, temperature, and load.