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MPG to Litres per 100 km Calculator

Convert US miles per gallon into the litres-per-100-km figure used across Europe and Australia.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
Miles per US gallon.

Use the figure from your own fill-to-fill measurement rather than the manufacturer's, which is measured on a test cycle. For a work vehicle, measure loaded — a laden pickup can be 30% worse than the same truck empty.

Fuel consumption

9.409 L/100 km

High confidence

L/100 km = 235.215 ÷ mpg. The constant is 3.785411784 L per US gallon divided by 1.609344 km per mile, times 100. The constant is exact. Real-world consumption varies with load, terrain, tyre pressure and driving far more than any rounding here.

US mpg entered
25 mpg
Imperial mpg (UK)
30.02 mpg (imp)
km per litre
10.63 km/L
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • 1 US gallon = 3.785411784 L (exact); 1 mile = 1.609344 km (exact)
  • 1 imperial gallon = 1.20095 US gallons, from the exact litre definitions

Inputs used

Fuel economy (mpg (US))
25

Intermediate steps

US mpg entered
25 mpg
Imperial mpg (UK)
30.02 mpg (imp)
km per litre
10.63 km/L
Final result9.41 L/100 km

Confidence note: L/100 km = 235.215 ÷ mpg. The constant is 3.785411784 L per US gallon divided by 1.609344 km per mile, times 100. The constant is exact. Real-world consumption varies with load, terrain, tyre pressure and driving far more than any rounding here.

What this calculation does not cover

  • The relationship is RECIPROCAL, not linear, and that has a practical consequence: you cannot average MPG figures. Two vehicles at 20 and 40 MPG do not average 30 over the same distance — they average 26.7, and working in litres per 100 km makes that arithmetic come out right.
  • This is the US gallon. An imperial gallon is about 20% larger, so a UK MPG figure converted here reads roughly 20% worse than it is.
  • A rated figure is a test cycle, not a plant run. Loaded trucks, cold starts, idling on site and a full rack of tools move real consumption well away from any published number.

Add the equipment this sizes

This result is a specification — 9.409 L/100 km — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations2
  1. 1 US gallon = 3.785411784 L (exact); 1 mile = 1.609344 km (exact)
  2. 1 imperial gallon = 1.20095 US gallons, from the exact litre definitions
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Plant and vehicle fuel budgets cross this boundary constantly — an American-specified machine working to a European fuel account, or a fleet quoted in one unit and invoiced in the other. The reciprocal relationship is also the reason a fleet manager should treat a 2 mpg gain on a truck as worth far more than the same gain on a van.

How to calculate MPG to litres per 100 km in 2 steps

  1. Fuel economy (mpg (US))Miles per US gallon.
  2. Fuel consumptionThe tool computes the fuel consumption from those figures and shows the formula, its sources, and a confidence rating alongside it.

MPG to Litres per 100 km at common values

Page defaults, not your figures above.

Fuel economy (mpg (US))Fuel consumption (L/100 km)
1515.7
2011.8
259.41
307.84
356.72
405.88
455.23
504.7

Frequently asked questions

Why is this a division rather than a multiplication?
Because the two units measure opposite things. Miles per gallon is distance per unit of fuel; litres per 100 km is fuel per unit of distance. One is the reciprocal of the other, which is why doubling mpg halves L/100 km rather than doubling it.
Is a UK mpg figure the same number?
No, and the gap is large. An imperial gallon is about 20% bigger than a US one, so the same vehicle scores roughly 20% higher in UK mpg. A car advertised at 40 mpg in Britain is about 33 mpg in the United States. The breakdown shows both.
Why do small mpg improvements matter more at the bottom of the range?
Because of the reciprocal. Going from 10 to 12 mpg saves far more fuel over the same distance than going from 40 to 42, even though both are a 2 mpg gain. This is the practical argument for concentrating efficiency effort on the thirstiest vehicle in a fleet, and it is invisible if you only ever look at mpg.
Which figure should I use for costing a job?
Whichever your fuel is sold in. Litres per 100 km multiplies straight into a litre price and a route distance; mpg needs a conversion first. For a fleet crossing between metric and imperial markets, cost in the local unit and convert the money, not the consumption.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.