Convert US Gallon to Imperial Fluid Ounce
Convert us gallons to imperial fluid ounces instantly. 1 us gallon = 133.2278695406 imperial fluid ounce — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Imperial Fluid Ounce to US Gallon converter for the reverse conversion.
Units explained
US Gallon
The US liquid gallon is defined as exactly 231 cubic inches (3.785411784 liters).
Based on the English wine gallon of 231 cubic inches, retained by the US after 1824.
The primary US unit for fuel, milk and large beverage containers.
English wine gallon; US since 1824.
Imperial Fluid Ounce
An imperial fluid ounce is 1/160 of an imperial gallon (28.4131 mL).
Defined so that ten fluid ounces make an imperial half-pint.
Used in UK and Commonwealth recipes and labels.
UK, 1824.
US Gallon to Imperial Fluid Ounce conversion formula
The relationship between us gallons and imperial fluid ounces:
To convert us gallons to imperial fluid ounces, multiply the value in us gallons by 133.2278695406. To reverse, multiply imperial fluid ounces by 0.007505937.
How to use this converter
Type a value into the calculator. The result in imperial fluid ounces updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Imperial Fluid Ounce to US Gallon converter for the reverse direction.
Step-by-step: convert us gallons to imperial fluid ounces
- Write down the value in us gallons (gal).
- Multiply that value by the factor 133.2278695406.
- The product is the equivalent value in imperial fluid ounces (fl oz).
- To reverse, multiply the imperial fluid ounce value by 0.007505937.
Worked examples
Example 1 — Convert 1 gal to fl oz:
1 × 133.2278695406 = 133.2278695406 fl oz
Example 2 — Convert 100 gal to fl oz:
100 × 133.2278695406 = 13322.7869540638 fl oz
Real-world example — Adjacent small-scale precision
One us gallon equals 1,000 imperial fluid ounces — the standard sub-millimeter precision conversion that materials engineers use whenever they switch between bulk material thickness specs (larger unit) and surface-finish characteristics (smaller unit).
1 gal × 133.2278695406 = 133.2278695406 fl oz
Real-world example — Adjacent metric sub-units
One us gallon equals 1,000 imperial fluid ounces. Engineers move between these scales constantly: PCB feature sizes in the larger unit, wire-bond diameters in the smaller.
1 gal × 133.2278695406 = 133.2278695406 fl oz
US Gallon to Imperial Fluid Ounce conversion table
Standard reference values for converting us gallons to imperial fluid ounces:
| US Gallon [gal] | Imperial Fluid Ounce [fl oz] |
|---|---|
| 0.01 | 1.3322786954 |
| 0.1 | 13.3227869541 |
| 1 | 133.2278695406 |
| 2 | 266.4557390813 |
| 3 | 399.6836086219 |
| 4 | 532.9114781626 |
| 5 | 666.1393477032 |
| 10 | 1332.2786954064 |
| 20 | 2664.5573908128 |
| 30 | 3996.8360862191 |
| 40 | 5329.1147816255 |
| 50 | 6661.3934770319 |
| 100 | 13322.7869540638 |
| 500 | 66613.9347703191 |
| 1000 | 133227.8695406382 |
Frequently asked questions
How many imperial fluid ounces is 1 us gallon?
How do I convert us gallons to imperial fluid ounces?
How do I convert imperial fluid ounces back to us gallons?
How many imperial fluid ounces is 100 us gallons?
Popular volume unit conversions
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Metric / SI (15 units)
US Customary (Liquid) (14 units)
US Customary (Dry) (5 units)
Imperial (UK) (14 units)
Cubic (length-derived) (4 units)
Cooking / Culinary (5 units)
Sources & references
Conversion factor (1 gal = 133.2278695406 fl oz) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.