Convert US Fluid Ounce to Imperial Fluid Ounce
Convert us fluid ounces to imperial fluid ounces instantly. 1 us fluid ounce = 1.0408427308 imperial fluid ounce — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Imperial Fluid Ounce to US Fluid Ounce converter for the reverse conversion.
Units explained
US Fluid Ounce
A US fluid ounce is 1/128 of a US gallon (29.5735 mL).
Derived from the gallon subdivision; distinct from the slightly smaller UK fluid ounce.
Standard for US beverage and nutrition labeling.
English customary; 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 Fluid Ounce to Imperial Fluid Ounce conversion formula
The relationship between us fluid ounces and imperial fluid ounces:
To convert us fluid ounces to imperial fluid ounces, multiply the value in us fluid ounces by 1.0408427308. To reverse, multiply imperial fluid ounces by 0.9607599404.
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 Fluid Ounce converter for the reverse direction.
Step-by-step: convert us fluid ounces to imperial fluid ounces
- Write down the value in us fluid ounces (fl oz).
- Multiply that value by the factor 1.0408427308.
- The product is the equivalent value in imperial fluid ounces (fl oz).
- To reverse, multiply the imperial fluid ounce value by 0.9607599404.
Worked examples
Example 1 — Convert 1 fl oz to fl oz:
1 × 1.0408427308 = 1.0408427308 fl oz
Example 2 — Convert 100 fl oz to fl oz:
100 × 1.0408427308 = 104.0842730786 fl oz
Real-world example — Hair-width scale measurements
A 70-us fluid ounce measurement (about the diameter of a human hair) is the kind of value materials engineers regularly express in adjacent micro-scale units like imperial fluid ounces for direct comparison across supplier datasheets.
70 fl oz × 1.0408427308 = 72.858991155 fl oz
Real-world example — Paper and film thicknesses
At the thickness of office paper (roughly 3 us fluid ounces), converting between sub-millimeter units is routine for packaging and printing buyers comparing quotes from metric and US suppliers.
3 fl oz × 1.0408427308 = 3.1225281924 fl oz
Real-world example — Plastic-film thickness alternates
A 150-us fluid ounce plastic film converts cleanly to imperial fluid ounces — useful for packaging buyers reconciling supplier datasheets across metric and US measurement systems.
150 fl oz × 1.0408427308 = 156.1264096179 fl oz
US Fluid Ounce to Imperial Fluid Ounce conversion table
Standard reference values for converting us fluid ounces to imperial fluid ounces:
| US Fluid Ounce [fl oz] | Imperial Fluid Ounce [fl oz] |
|---|---|
| 0.01 | 0.0104084273 |
| 0.1 | 0.1040842731 |
| 1 | 1.0408427308 |
| 2 | 2.0816854616 |
| 3 | 3.1225281924 |
| 4 | 4.1633709231 |
| 5 | 5.2042136539 |
| 10 | 10.4084273079 |
| 20 | 20.8168546157 |
| 30 | 31.2252819236 |
| 40 | 41.6337092314 |
| 50 | 52.0421365393 |
| 100 | 104.0842730786 |
| 500 | 520.4213653931 |
| 1000 | 1040.8427307862 |
Frequently asked questions
How many imperial fluid ounces is 1 us fluid ounce?
How do I convert us fluid ounces to imperial fluid ounces?
How do I convert imperial fluid ounces back to us fluid ounces?
How many imperial fluid ounces is 100 us fluid ounces?
Popular volume unit conversions
Convert US Fluid Ounce to other volume units
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Metric / SI (8 units)
US Customary (Liquid) (7 units)
Imperial (UK) (4 units)
Cubic (length-derived) (3 units)
Cooking / Culinary (3 units)
Sources & references
Conversion factor (1 fl oz = 1.0408427308 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 Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.