US gallons and US quarts
The US liquid gallon is defined as exactly 231 cubic inches, which is 3.785411784 liters. Gasoline, milk and paint are sold by the gallon in the US.
The US liquid quart is a quarter of a US gallon: exactly 0.946352946 liters, or 2 pints. Motor oil, milk, stock and ice cream are sold in quarts in the US.
Worked example
Convert 1.5 gal: 1.5 × 4 = 6, so 1.5 US gallons is 6 US quarts. Likewise 2 gal = 8 qt.
Estimating in your head
The factor is a short exact number, so mental math needs no rounding: multiply by 4.
Going the other way
To convert US quarts to US gallons, divide by 4 (or multiply by 0.25).
How this works
qt = gal × 4
1 gal = 0.003785411784 m³ and 1 qt = 0.000946352946 m³, both by definition, so the factor is their ratio: 4 exactly. Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.
Frequently asked
How many US quarts are in a US gallon?
1 US gallon = 4 US quarts, exactly. The value follows from the unit definitions, so it never changes.
How do I convert US gallons to US quarts?
Multiply by 4. For example, 2 gal × 4 = 8 qt.
What is 10 gal in US quarts?
10 gal = 40 qt. The table next to the converter lists more common values.
Is the result rounded?
Only on screen. The page computes with the exact definitions and removes floating-point noise past 15 significant digits; pick 3 to 12 significant figures, or use Copy result for the full value.
Sources
- NIST SP 811 Appendix B.8 — Factors for units listed alphabetically
- NIST Handbook 44 — Appendix C, General tables of units of measurement
- Wikipedia — United States customary units
Reviewed Oct 17, 2026 · test vectors fixtures/units/volume/gallons-to-quarts/