Quarts, gallons and liters for paint

Last reviewed: November 2, 2026

A US gallon is 4 quarts, or 3.785 liters. An imperial gallon is 4.546 liters, about 20% bigger, so following a figure from a British source can put your estimate off by about a fifth.

The exact definitions are 1 US gallon = 3.785411784 liters (NIST) and 1 imperial gallon = 4.54609 liters (UK Weights and Measures Act 1985).

Conversion table

Why this matters for paint

Take the 379 sq ft job from our wall measuring guide, with two coats at 350 sq ft per gallon.

The arithmetic gives 2.17 gallons either way, but those gallons aren’t the same size:

That’s a gap of about 1.6 liters. Paint in the US is sold in quarts and gallons, and in the UK in liters. The risk comes from following advice written for another country, or an online calculator that just says “gallons”.

Converting a coverage figure

A coverage figure has both an area and a volume in it, so both need converting.

For example, 350 sq ft per US gallon ÷ 40.75 = 8.59 m²/L. The same 350 per imperial gallon is 7.15 m²/L.

Common mistakes

• Seeing “gal” and assuming. Check which country the source is from.
• Comparing can sizes across countries. A 5 L can is a little over 1.3 US gallons, not “about a gallon”.
• Treating a quart as a liter. A US quart is 0.946 L, about 5% smaller.
• Converting the area only. Change sq ft to m² without changing gallons to liters, and the result is wrong.

The calculator always names which gallon it means, and shows quantities in US gallons, liters, and imperial gallons together.

Sources

• NIST Handbook 44 (2026), Appendix C
• UK Weights and Measures Act 1985, Schedule 1