--- title: "1 gal to fl oz = 128 fl oz" description: "1 US gallon is 128 US fluid ounces. The arithmetic, a table of nearby values, and a converter for any other number." url: https://atoneplace.net/convert/1-gallons-to-fl-oz/ site: "At One Place" --- # 1 gal to fl oz **1 US gallon in US fluid ounces: 1 gal = 128 fl oz** fl oz = gal × 128 1 US gallon is 128 US fluid ounces. To get there, multiply by 128. ## Values either side *US gallons near 1, converted to US fluid ounces.* | US gallons | US fluid ounces | | --- | --- | | 0.5 gal | 64 | | 1 gal ← | 128 | | 1.5 gal | 192 | | 2 gal | 256 | | 2.5 gal | 320 | | 3 gal | 384 | ## How the conversion works The relationship is fl oz = gal × 128. Both units measure volume, so the conversion is a fixed factor that never changes. The figure is exact rather than approximate: since the international yard and pound agreement of 1959, an inch is defined as exactly 25.4 millimetres and a pound as exactly 0.45359237 kilograms, and every other imperial and US customary unit here is derived from those two. > US gallon: US liquid gallon. The imperial gallon is about 20% larger. ## Common questions ### What is 1 gal in US fluid ounces? 1 gal is 128 fl oz. ### How do you convert US gallons to US fluid ounces? Multiply by 128. ## Related pages - [US gallons to US fluid ounces](https://atoneplace.net/convert/gallons-to-fl-oz/) - [1 fl oz to gal](https://atoneplace.net/convert/1-fl-oz-to-gallons/) - [0.5 gal to fl oz](https://atoneplace.net/convert/0-5-gallons-to-fl-oz/) - [1.5 gal to fl oz](https://atoneplace.net/convert/1-5-gallons-to-fl-oz/) - [2 gal to fl oz](https://atoneplace.net/convert/2-gallons-to-fl-oz/) - [2.5 gal to fl oz](https://atoneplace.net/convert/2-5-gallons-to-fl-oz/) - [3 gal to fl oz](https://atoneplace.net/convert/3-gallons-to-fl-oz/) ## Sources - Guide for the Use of the International System of Units (SP 811) — NIST (https://www.nist.gov/pml/special-publication-811) [Public domain (US Government)] - The International System of Units (SI Brochure) — Bureau International des Poids et Mesures (https://www.bipm.org/en/publications/si-brochure) - Calculated on this page — At One Place (/about/)