MPG to L/100km Converter
Convert US miles per gallon to liters per 100 km for comparing vehicle fuel economy.
How It Works
Formula: MPG to L/100km = 235.214583 ÷ value
Example: 30 MPG = 7.840486 L/100km
Note: MPG converts to L/100km using L/100km = 235.215 ÷ MPG, based on the US gallon.
Common Uses
Quick Conversion Table
| MPG | L/100km |
|---|---|
| 10 | 23.5215 |
| 20 | 11.7607 |
| 25 | 9.4086 |
| 30 | 7.8405 |
| 40 | 5.8804 |
| 50 | 4.7043 |
Rounding Rule
Rounded to 2 decimal places
Error Margin
±0.01 L/100km
Precision Guidance
For car shopping, round to 1 decimal. For detailed comparison, keep 2 decimals.
Common Mistakes
MPG and L/100km are inversely related—a higher MPG means a lower L/100km. Do not multiply directly.
Frequently Asked Questions
What is 30 MPG in L/100km?
30 MPG equals 7.84 L/100km using the formula L/100km = 235.215 ÷ MPG.
How do I convert MPG to L/100km?
Divide 235.215 by the MPG value. For example, 235.215 ÷ 30 = 7.84 L/100km.
Why is the relationship inverse?
Higher MPG is better (more efficient), but lower L/100km is better. The two scales move in opposite directions.
Is this the US gallon?
Yes, this uses the US gallon (3.785 L). The UK imperial gallon gives different results.
Deep Dive Guide
MPG to L/100km: Convert US Fuel Economy to European Ratings
Convert MPG to L/100km with the exact inverse formula (235.215 / MPG). Compare US fuel economy with European ratings for cars, rentals, and reviews.
Read Full Guide →More Converters You May Like
Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 US MPG → L/100 km: L/100 km = 235.214583 ÷ MPG (exact, US gal = 3.785411784 L, 1 mi = 1.609344 km)
- EXACT1 US MPG = 0.425143707 km per litre (exact)
- EXACT1 Imperial MPG (UK) uses a 4.54609 L gallon — not interchangeable with US MPG
Common Pitfalls & How to Avoid Them
US MPG vs. UK MPG
A UK gallon is 4.54609 L, so 40 UK MPG ≈ 33.3 US MPG. Comparing trans-Atlantic fuel figures directly overstates economy.
L/100 km is inverse
Higher MPG = better; higher L/100 km = worse. Use L/100 km = 235.214583 ÷ US MPG, never a straight subtraction.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
Last Updated 2026 | This converter was reviewed for accuracy