# US miles per gallon to liters per 100 km converter

> Convert US miles per gallon to liters per 100 km (mpg to L/100km) with the exact formula, a conversion chart and worked steps.

Interactive version: https://www.calcopenly.com/conversion/mpg-to-l-100km
Subject: Unit converters

A US miles-per-gallon rating describes distance traveled for a fixed fuel amount. Converting it to consumption per distance reverses the scale: a larger mpg value becomes a smaller liters-per-100-kilometers value. UK imperial mpg needs a different gallon definition.

US miles per gallon and liters per 100 km are not related by a single multiplier: fuel consumption per distance is the reciprocal of distance per fuel, so the conversion uses a formula. 30 mpg (US) is 7.8405 L/100 km.

235.214583 is the number of litres per 100 km at 1 US mpg (100 km × 3.785411784 L per gallon ÷ 1.609344 km per mile). Higher mpg means lower L/100 km, and the relationship is a curve, not a straight line.

## Inputs

- **US miles per gallon (mpg (US))**

## Results

- Liters per 100 km (L/100 km) — main result
- Conversion
- 1 L/100 km in US miles per gallon (mpg (US))

## Formula

$$
\text{L/100 km} = \frac{235.214583\ldots}{\text{mpg}}
$$

## Worked examples

### 30 mpg (US) to L/100 km

- US miles per gallon (mpg (US)): 30 mpg (US)
- **Liters per 100 km: 7.8404861111 L/100 km**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 25 mpg (US) to L/100 km

- US miles per gallon (mpg (US)): 25 mpg (US)
- **Liters per 100 km: 9.4085833333 L/100 km**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 50 mpg (US) to L/100 km

- US miles per gallon (mpg (US)): 50 mpg (US)
- **Liters per 100 km: 4.7042916667 L/100 km**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert mpg to L/100km?

A US miles-per-gallon rating describes distance traveled for a fixed fuel amount. Converting it to consumption per distance reverses the scale: a larger mpg value becomes a smaller liters-per-100-kilometers value. UK imperial mpg needs a different gallon definition.

### What is the formula to convert mpg to L/100km?

Divide 235.214583 by the value: 30 US mpg is 235.214583 ÷ 30 = 7.84 L/100 km, and 6 L/100 km is 235.214583 ÷ 6 = 39.2 mpg. The same formula works in both directions because each unit is the reciprocal of the other, scaled.

### How accurate is the US miles per gallon to liters per 100 km converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “30 mpg (US) to L/100 km” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C: General tables of units of measurement](https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/handbook-44)
- [BIPM, The International System of Units (SI Brochure), 9th edition](https://www.bipm.org/en/publications/si-brochure)