Fuel Consumption Converter
Convert between MPG (US/UK), L/100km, km/L, and more fuel economy units.
The two units move in opposite directions, and the curve is steep at the bottom: going from 10 to 20 mpg saves far more fuel than going from 40 to 50, even though both are a 10 mpg gain.
Instant insight
MPG and L/100km run in opposite directions
Higher mpg is better; lower L/100km is better. The relationship is a reciprocal, so the same absolute change means very different things at each end.
Going from 20 to 25 mpg saves far more fuel than going from 40 to 45 — compare in L/100km to see why.
Check the direction of the conversion
Going from l_per_100km to km_per_l, the number should get bigger if the new unit is smaller, and smaller if it is bigger.
If it moved the wrong way, the factor has been applied upside down — the most common conversion error there is.
Worked out in your browser — nothing is sent anywhere. Comparison figures are approximate.
Common conversions
Quick Reference — 1 unit = ? Kilometers per Liter (km/L)
| Unit | Value |
|---|---|
| Liters per 100 km (L/100km) | 100 |
| Kilometers per Liter (km/L) | 1 |
| Miles per Gallon (US MPG) | 0.4251429543 |
| Miles per Gallon (UK MPG) | 0.3540061101 |
| Liters per Kilometer (L/km) | 1 |
Formula
MPG(US) = 235.215 / L/100km | km/L = 100 / L/100km
Everyday Uses
Road trip budgeting
Convert your car's consumption into an exact fuel cost for the trip before you leave.
Car shopping
Compare MPG and L/100km across listings from different countries on equal terms.
Tracking efficiency
A sudden drop in fuel economy can flag maintenance issues early — track fill-ups and compare.
Cutting costs
See what better driving habits or a more efficient car would save you per year.
Comparing two cars
Convert mpg to litres per 100 km — the metric figure scales linearly, so improvements are easier to judge.
Imperial versus US gallons
An imperial gallon is about 20% larger, so UK and US mpg figures are not directly comparable without converting.
Frequently Asked Questions
How do you convert L/100km to MPG (and vice versa)?
US MPG = 235.215 ÷ L/100km. UK MPG = 282.481 ÷ L/100km. L/100km = 235.215 ÷ US MPG. Examples: 8 L/100km = 29.4 US MPG = 35.3 UK MPG. 6 L/100km = 39.2 US MPG (very fuel-efficient). 12 L/100km = 19.6 US MPG (typical SUV). 30 US MPG = 7.84 L/100km. Note: L/100km and MPG are inversely related — a lower L/100km is better; a higher MPG is better.
What is the difference between US MPG and UK MPG?
The UK (imperial) gallon is 4.546 litres; the US gallon is 3.785 litres — about 20% smaller. So the same car always shows higher MPG in UK measurement than US. A car rated 40 UK MPG = 33.3 US MPG = 7.06 L/100km. When comparing vehicle fuel economy across countries or car reviews, always check which gallon is being used. European reviews typically use L/100km; American reviews use US MPG; UK reviews may use either.
What are typical fuel consumption figures for different vehicle types?
Reference fuel economy benchmarks: Small city car (e.g. VW Polo): 5–6 L/100km = 39–47 US MPG. Family sedan (e.g. Toyota Camry): 7–9 L/100km = 26–34 US MPG. SUV (e.g. Ford Explorer): 10–13 L/100km = 18–24 US MPG. Pickup truck (full-size): 13–16 L/100km = 15–18 US MPG. Hybrid (e.g. Toyota Prius): 4–5 L/100km = 47–59 US MPG. Electric vehicle: expressed in kWh/100km or miles per kWh (e.g. 15 kWh/100km = 6.7 km/kWh = about 3–4 miles/kWh).
How do you calculate fuel cost for a trip?
Fuel cost = (Distance ÷ Fuel economy) × Fuel price. In metric: (kilometres ÷ 100) × L/100km × price per litre = total fuel cost. Example: 500 km trip, car uses 7 L/100km, fuel costs £1.50/L: (500 ÷ 100) × 7 × 1.50 = 5 × 7 × 1.50 = £52.50. In US: miles ÷ MPG = gallons needed × $/gallon = cost. Example: 300 miles, 30 MPG, $3.50/gal: 300 ÷ 30 = 10 gal × $3.50 = $35.00.
How does driving style and speed affect fuel consumption?
Fuel consumption rises significantly at motorway speeds due to aerodynamic drag, which increases with the square of speed. Driving at 110 km/h (68 mph) typically uses 15–25% more fuel than at 90 km/h (56 mph). Aggressive acceleration and heavy braking can increase consumption by 20–40% vs. smooth driving. Other fuel-saving tips: tyre inflation (under-inflated tyres increase rolling resistance by ~2–3% per 10 psi drop), air conditioning adds ~5–10% consumption, and roof boxes/carriers can add 10–15% at highway speeds.