Cups to Gallons Converter

This calculator converts cups to gallons for both the US customary and UK imperial measurement systems, and works in reverse from gallons back to cups too. It matters whenever you are scaling a recipe up from cups to a bulk gallon quantity, working out how many cups fill a gallon jug, or converting between US and UK measurements because the two systems use different unit sizes. You choose your measurement system, US customary where one cup equals 236.588 mL, or UK imperial where one cup equals 284.131 mL, then enter your number of cups, or enter a gallon figure instead and the calculator fills in the equivalent cups for you. A quick preset dropdown lets you jump straight to common amounts like 4 cups (one quart), 8 cups (half a gallon) or 16 cups (one gallon). The result panel returns your total in gallons, litres and millilitres, along with the cups-per-gallon ratio, which is 16 in both systems even though a UK cup and gallon hold more liquid than their US equivalents. Below the calculator, a quick reference table lists conversions for common cup quantities from 1 cup up to 64 cups (4 gallons), with your selected amount highlighted. Because the ratio is fixed and exact, results are precise rather than estimates, but always check whether your recipe uses US or UK cups before converting.

Calculate.co.nz is proud to be partnered with Premium Homes, a recognised leader in eco-friendly, sustainable, and energy-efficient homebuilding. With a dedicated team and award-winning experience, they create homes that prioritise health, comfort, and long-term performance. Their founders, Andrew and Kelly, set out to raise the standard of residential construction in New Zealand by combining practical building expertise with a clear commitment to doing things better for homeowners.
Calculate.co.nz partner: Premium Homes
Standard conversion  US customary and UK imperial definitions. NIST Handbook 44.

1. Enter Cups

2. Or Enter Gallons (reverse)

Conversion Result

Gallons
1
US gallons
Litres
3.785
L
Millilitres
3,785
mL
Cups per Gallon
16
cups per US gallon

Quick Reference Table

CupsGallonsLitresMillilitresCommon name

How to Convert Cups to Gallons

The conversion between cups and gallons is straightforward in both the US and UK measurement systems. In the US system, one cup equals exactly 8 US fluid ounces, or 236.588 mL. There are 16 cups in a US gallon, so the formula is:

Gallons = Cups ÷ 16

To go the other way, from gallons to cups:

Cups = Gallons × 16

For example, 4 cups divided by 16 equals 0.25 gallons (one quarter of a gallon, also called a quart). And 2 gallons multiplied by 16 equals 32 cups.

US vs UK Measurement Systems

The US and UK use different definitions for cups and gallons, so it is important to know which system applies to your recipe or task.

MeasurementUS customaryUK imperial
1 cup236.588 mL284.131 mL
1 gallon3,785.41 mL (3.785 L)4,546.09 mL (4.546 L)
Cups per gallon1616
Fluid ounces per cup8 US fl oz10 UK fl oz
Pints per gallon88

Both systems have 16 cups per gallon because the ratio of cup to gallon is the same in each system (both divide the gallon into 8 pints and each pint into 2 cups). However, because the underlying volumes differ, a UK cup holds more than a US cup, and a UK gallon holds more than a US gallon.

Most recipes from the United States use US cups. Recipes from the United Kingdom, Australia, Canada, and New Zealand typically use metric measures (mL and L), though older recipes may reference imperial cups.

Common Cup Conversions

CupsUS GallonsUS LitresCommon name
10.06250.2371 cup
20.1250.4731 US pint
40.250.9461 US quart
80.51.893Half gallon
1613.7851 US gallon
3227.5712 US gallons
64415.1424 US gallons

Worked Example

You need to convert 16 cups to gallons for a US recipe.

Gallons = 16 ÷ 16 = 1 gallon

In litres: 16 × 236.588 mL = 3,785.41 mL = 3.785 litres

This matches the default result shown in the calculator above.

Related Calculators

Sources and method: US cup defined as 8 US fluid ounces = 236.5882365 mL (NIST Handbook 44). US gallon = 231 cubic inches = 3,785.411784 mL. UK imperial cup = 10 UK fluid ounces = 284.130625 mL. UK gallon = 4,546.09 mL (Weights and Measures Act 1985). Ratio: 16 cups per gallon in both systems.

This converter uses exact definitions for US customary and UK imperial units. For cooking purposes, small rounding differences between measurement systems are generally insignificant. Always check which cup size your recipe uses before converting.

Frequently asked questions

How many cups are in a gallon?

There are 16 US cups in 1 US gallon. Each US cup holds 236.588 mL and a US gallon holds 3,785.41 mL (3.785 litres). In the UK system, 1 UK gallon equals approximately 16 UK cups, since a UK cup is 284.131 mL and a UK gallon is 4,546.09 mL. However, UK cups are not as commonly used in recipes as US cups.

How do I convert cups to gallons?

To convert US cups to US gallons, divide the number of cups by 16. For example, 8 cups divided by 16 equals 0.5 gallons (half a gallon). To convert gallons back to cups, multiply by 16. For UK measurements, divide UK cups by 16 to get UK gallons, as the ratio is the same (a UK imperial cup is defined as half an imperial pint, which is 10 imperial fluid ounces, and there are 8 pints in an imperial gallon, so there are 16 cups per gallon).

Is a US gallon the same as a UK gallon?

No. A US gallon is 3,785.41 mL (approximately 3.785 litres), while a UK imperial gallon is 4,546.09 mL (approximately 4.546 litres). A UK gallon is about 20 percent larger than a US gallon. If you are following a US recipe using US cups, use the US gallon conversion. If you are working with UK or imperial measurements, use the UK gallon.

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

Calculate.co.nz is the sister site of CalculatorHub.com, the world's largest calculator website by tool count.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Health Based Building to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland by SiteHost New Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.

About & trust: Why Calculate is NZ's most comprehensive · By the Numbers · How we compare · Editorial standards · How we keep data current · NZ finance glossary · Research & data · Financial literacy NZ · About · Free API · Privacy policy · Terms of use

Reviewed and maintained. Last reviewed 2026-08-15 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.

© 2026 Calculate.co.nz. All rights reserved. Building free NZ calculators since 2019.