conversions
How Many Cups in a Gallon
Last updated: May 31, 2026
Written by Blake Boege
A cups-in-a-gallon conversion page translates volumes between cups and gallons. In the US Customary system, a liquid gallon contains exactly 16 cups (each cup being 8 US fluid ounces). In the British Imperial system, a gallon contains approximately 18.18 Imperial cups (each cup being 10 Imperial fluid ounces). The page helps cooks scale recipe liquids accurately.
Convert gallons to cups and cups to gallons instantly. Learn about differences in cup sizes between US customary, legal, and Imperial measurement standards.
Quick Answer
Find out exactly how many cups are in a US gallon (16 cups) or an Imperial gallon (18.18 cups) and convert volumes instantly.
How Many Cups in a Gallon?
There are 16 cups in a US gallon.
In the Imperial system, there are approximately 18.18 cups in a gallon.
Liquid Measurement System
Formula: 1 Gallon = 16 US Cups
US Gallons to Cups Table
| Gallons (gal) | Cups |
|---|---|
| 1/16 gal (1 Cup) | 1 cup |
| 1/8 gal (1 Pint) | 2 cups |
| 1/4 gal (1 Quart) | 4 cups |
| 1/2 gal | 8 cups |
| 1 gal | 16 cups |
| 2 gal | 32 cups |
| 5 gal | 80 cups |
| 10 gal | 160 cups |
Imperial Gallons to Cups Table
| Imperial Gallons (gal) | Cups |
|---|---|
| 1/8 gal | 2.27 cups |
| 1/4 gal | 4.55 cups |
| 1/2 gal | 9.09 cups |
| 1 gal | 18.18 cups |
| 2 gal | 36.36 cups |
| 5 gal | 90.91 cups |
| 10 gal | 181.82 cups |
Examples
1 Gallon (US)
16 Cups
1 Gallon (Imperial)
18.18 Cups
5 Gallons (US)
80 Cups
How it works
The number of cups in a gallon varies depending on whether you are using the United States Customary system or the British Imperial system:
US Customary System
1 Gallon = 16 Cups
Imperial System (UK)
1 Gallon = 18.18 Cups
Comparing Three Different Cup Sizes
Depending on what recipe or country you are cooking in, the standard cup size can actually take three different values:
- US Customary Cup: Primarily used in US home recipes. It is defined as 8 US fluid ounces, which is approximately 236.59 milliliters.
- US Legal Cup: Used in the United States for FDA nutrition labeling. It is rounded to exactly 240 milliliters.
- Imperial Cup: Used historically in the UK and Commonwealth countries. It is defined as 10 Imperial fluid ounces, which is approximately 284.13 milliliters.
Quick Kitchen Reference Guide
When baking or cooking, remember these basic US liquid equivalencies:
1 Cup = 8 Fluid Ounces = 16 Tablespoons
1 Pint = 2 Cups = 16 Fluid Ounces
1 Quart = 2 Pints = 4 Cups = 32 Fluid Ounces
1 Gallon = 4 Quarts = 8 Pints = 16 Cups = 128 Fluid Ounces
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Frequently asked questions
There are 8 cups in a half gallon (US Customary) and approximately 9.09 cups in a half gallon (Imperial).
There are exactly 80 cups in 5 gallons (US Customary) and approximately 90.91 cups in 5 gallons (Imperial).
The two systems evolved separately. The US customary system is historically based on the English wine gallon (3.785 liters), defining a cup as 8 US fluid ounces. The British Imperial system (reformed in 1824) is based on the volume of 10 pounds of water (4.546 liters), defining a cup as 10 Imperial fluid ounces.
There are 4 cups in a quart (in both systems, since a quart is always 1/4 of a gallon, and a cup is 1/16 of a gallon: 16 ÷ 4 = 4).
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