US liquid gallon to Imperial fluid ounce
gal
imp fl oz
Conversion History
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Quick Reference Table (US liquid gallon to Imperial fluid ounce)
| US liquid gallon (gal) | Imperial fluid ounce (imp fl oz) |
|---|---|
| 0.5 | 66.6139347705952894559 |
| 1 | 133.22786954119057891179 |
| 2 | 266.45573908238115782359 |
| 5 | 666.13934770595289455896 |
| 10 | 1,332.27869541190578911793 |
| 50 | 6,661.39347705952894558964 |
About US liquid gallon (gal)
The US liquid gallon is a unit of volume equal to 4 quarts, 8 pints, or 128 US fluid ounces, approximately 3.785 liters. It is the primary large liquid volume unit in the United States, used for fuel pricing at the pump, milk and juice packaging, and paint. US fuel economy is measured in miles per gallon (MPG). The US gallon is about 17% smaller than the UK imperial gallon (4.546 L), causing significant differences in fuel economy comparisons.
A gallon jug of milk is 3.785 L. Petrol (gasoline) is priced per US gallon at every US fuel station.
About Imperial fluid ounce (imp fl oz)
The imperial fluid ounce (imp fl oz) is a unit of volume equal to one twentieth of an imperial pint, approximately 28.413 milliliters. It is used in the United Kingdom and Commonwealth countries, though metric units have replaced it in most commercial contexts. The imperial fluid ounce is slightly smaller than the US fluid ounce (29.574 mL). UK spirits measures are now defined by law in 25 mL and 35 mL metric measures, which do not align exactly with the imperial fluid ounce.
A single spirits measure in a UK bar is 25 mL or 35 mL — close to, but not exactly, one imperial fluid ounce (28.41 mL).
US liquid gallon – Frequently Asked Questions
Why does the US still price fuel per gallon when the rest of the world uses liters?
US fuel infrastructure — pumps, tax law, pipeline contracts, and consumer expectations — is built around the gallon. Federal and state fuel taxes are levied per gallon; EPA fuel economy standards use miles per gallon; and consumers benchmark prices against a gallon reference ("$3 a gallon"). Switching to liters would require reprogramming every pump, rewriting tax code, and re-educating 330 million people who compare prices by the gallon. Canada made the switch in the 1970s during a broader metrication push, but the US never had the political will for a comprehensive changeover.
Why is the US gallon smaller than the UK gallon?
The US gallon (3.785 L) is based on the Queen Anne wine gallon of 1707 (231 cubic inches). The UK imperial gallon (4.546 L) was defined in 1824 as the volume of 10 pounds of water. The two systems diverged after US independence.
How does US MPG compare to L/100km?
To convert: L/100km = 235.2 ÷ MPG (US). A car achieving 30 MPG uses about 7.8 L/100km. UK MPG values are always higher than US MPG for the same car because the imperial gallon is larger.
How many gallons of water does a person drink per day?
Recommended daily water intake is about 2–3 liters (roughly 0.5–0.8 US gallons). The commonly cited "8 glasses a day" ≈ 64 fl oz ≈ 0.5 gallons ≈ 1.9 liters.
How many gallons does a car fuel tank hold?
Most US passenger cars have fuel tanks of 10–20 gallons (38–76 liters). Compact cars are typically 10–13 gallons; mid-size cars 14–17 gallons; SUVs and trucks 18–36 gallons.
Imperial fluid ounce – Frequently Asked Questions
Why did the UK abandon the fluid ounce for spirits but keep the pint for beer?
When the UK metricated in the 1990s, spirits measures were switched to 25 mL and 35 mL because publicans needed precise, legally enforceable pour sizes — and optic dispensers were easy to replace with metric ones. Beer, however, had enormous cultural resistance: the "pint" is deeply embedded in British pub identity, and the Campaign for Real Ale lobbied hard. Parliament granted an explicit exemption allowing draft beer and cider to be sold by the imperial pint. Milk got a similar exemption. The result is a hybrid system where your gin is metric but your beer is imperial.
How many imperial fluid ounces are in a UK pint?
There are exactly 20 imperial fluid ounces in one UK pint (568 mL). In the US system, 1 pint = 16 US fluid ounces (473 mL).
Is the imperial fluid ounce still used?
The imperial fluid ounce is rarely used for commercial transactions in the UK today, which metricated in the 1990s. UK spirits servings are now legally defined in metric (25 mL or 35 mL).
Why is a UK shot 25 mL not one fluid ounce?
When the UK metricated bar measures, the 25 mL "metric measure" replaced older imperial measures. One imperial fl oz (28.41 mL) was not adopted because the EU standardized on 25 mL. So UK shots are not exactly one fl oz.
How many milliliters are in an imperial fluid ounce?
One imperial fluid ounce equals approximately 28.413 mL. One US fluid ounce equals approximately 29.574 mL. Both round to roughly "30 mL" in casual usage, but the precise difference matters in pharmacology.