Tutorial

How to Convert Liters to Gallons

A thorough guide to converting liters to gallons, covering both US and Imperial gallons, with precise formulas, real-world examples, and the critical differences you need to know.

Last updated: 2025-03-13

Two Types of Gallons: US vs. Imperial

Before converting liters to gallons, you must know which gallon you are working with. There are two standard gallons in use today, and they differ by roughly 20%. Confusing the two can lead to significant errors in fuel calculations, recipes, and shipping estimates.

  • US gallon: 3.78541 liters (used in the United States, Latin America, and some Caribbean nations)
  • Imperial gallon: 4.54609 liters (used in the United Kingdom, Canada for some purposes, and a few other Commonwealth countries)

An Imperial gallon is about 20% larger than a US gallon. This difference is not trivial. If you buy 10 gallons of fuel, the Imperial measure gives you nearly 2 extra liters compared to the US measure.

The Formulas

Liters to US Gallons

US gallons = liters / 3.78541

Liters to Imperial Gallons

Imperial gallons = liters / 4.54609

Step-by-Step Example: Converting 20 Liters

To US Gallons

  • Step 1: Take the volume: 20 liters.
  • Step 2: Divide by 3.78541: 20 / 3.78541 = 5.283.
  • Result: 20 liters equals approximately 5.28 US gallons.

To Imperial Gallons

  • Step 1: Take the volume: 20 liters.
  • Step 2: Divide by 4.54609: 20 / 4.54609 = 4.399.
  • Result: 20 liters equals approximately 4.40 Imperial gallons.

Notice the difference: the same 20 liters gives you 5.28 US gallons but only 4.40 Imperial gallons. Our Gallons to Liters converter handles both types automatically.

The Reverse: Gallons to Liters

To convert gallons back to liters, simply multiply:

  • US gallons to liters: liters = US gallons × 3.78541
  • Imperial gallons to liters: liters = Imperial gallons × 4.54609

Fuel Economy: Why This Matters for Cars

Fuel economy is one of the most common reasons people need this conversion. Different countries express fuel efficiency in different ways:

  • US: miles per gallon (mpg, using US gallons)
  • UK: miles per gallon (mpg, using Imperial gallons)
  • Most of Europe, Asia: liters per 100 kilometers (L/100km)

This creates a confusing situation. A car rated at 40 mpg in the UK is actually more efficient than one rated at 40 mpg in the US, because the Imperial gallon is larger. In UK mpg, 40 mpg equals about 7.06 L/100km, while 40 US mpg equals about 5.88 L/100km. Always check which gallon is being referenced when comparing fuel economy figures from different countries.

Cooking and Beverage Contexts

In cooking, you are more likely to encounter quarts, cups, and fluid ounces than full gallons. However, for large-batch brewing, canning, or commercial food preparation, gallon and liter conversions are routine. Key cooking relationships include:

  • 1 US gallon = 16 US cups = 3.785 liters
  • 1 US quart = 4 US cups = 0.946 liters (close to 1 liter)
  • 1 liter = 4.227 US cups
  • 1 Imperial gallon = 4 Imperial quarts = 4.546 liters

A useful approximation: one US quart is very close to one liter (within 6%), so for rough cooking estimates, you can treat them as equal.

Common Conversions Reference

  • 1 liter = 0.264 US gal / 0.220 Imperial gal
  • 2 liters = 0.528 US gal / 0.440 Imperial gal (a standard soda bottle)
  • 5 liters = 1.321 US gal / 1.100 Imperial gal
  • 10 liters = 2.642 US gal / 2.200 Imperial gal
  • 20 liters = 5.283 US gal / 4.399 Imperial gal (a common jerry can)
  • 50 liters = 13.209 US gal / 10.998 Imperial gal (a standard fuel tank)
  • 100 liters = 26.417 US gal / 21.997 Imperial gal

Quick Mental Math

For a fast estimate of liters to US gallons, divide by 4 and add a bit. More precisely, multiply the liter value by 0.26. For 40 liters: 40 × 0.26 = 10.4 US gallons (actual: 10.57). For Imperial gallons, divide by 4.5 or multiply by 0.22.

Quick Reference Section

Keep these formulas handy:

  • Liters to US Gallons: liters / 3.78541
  • Liters to Imperial Gallons: liters / 4.54609
  • US Gallons to Liters: gallons × 3.78541
  • Imperial Gallons to Liters: gallons × 4.54609
  • Key fact: 1 Imperial gallon is about 20% larger than 1 US gallon
  • Quick estimate: 1 US quart ≈ 1 liter (within 6%)

Use our free Gallons to Liters converter or the comprehensive volume converter for precise results across all volume units.