How Many Ounces in a Gallon?

There are 128 fluid ounces in a US gallon and 160 fluid ounces in a UK (imperial) gallon.

How many ounces in a gallon? — see the answer and conversion table below.

Use the related converter below for custom values.

Formula

Answer: There are 128 fluid ounces in a US gallon and 160 fluid ounces in a UK (imperial) gallon.

Example

Question: How many ounces in a gallon? Answer: There are 128 fluid ounces in a US gallon and 160 fluid ounces in a UK (imperial) gallon.

How to Use

  1. Read the direct answer at the top of the page
  2. Check the conversion table for common values
  3. Use the related converter for custom values
  4. Browse the FAQ for common follow-up questions

Frequently Asked Questions

How many water bottles in a gallon?

A standard 16.9 oz water bottle means about 7.57 bottles per gallon. A 8 oz bottle means 16 bottles per gallon.

How many ounces in a half gallon?

There are 64 fluid ounces in a half gallon (US).

Is a fluid ounce the same as a weight ounce?

No. A fluid ounce measures volume (29.57 ml), while a weight ounce measures mass (28.35 g). They differ for most substances.

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Author: Calczy Editorial Team Reviewed by: Calczy Editorial Team Last updated: 2026-09-16

This page was reviewed for accuracy by the Calczy editorial team. Our editorial process follows our editorial policy to ensure reliable, up-to-date conversion tools and reference content.