A fluid ounce (US) is a unit of volume used to measure liquids in the U.S. customary system. It's abbreviated as fl oz and is commonly seen in cooking, nutrition labeling, and liquid packaging. One US fluid ounce is defined as 1/128 of a US gallon, which equals exactly 29.5735 milliliters.
Despite the term "ounce" also being used for weight, a fluid ounce specifically measures liquid volume. It's important to distinguish the two, especially in recipes or products where both liquid and solid measurements appear. The US fluid ounce is a standard unit across many industries, from beverages and sauces to cleaning products and personal care items,
Uses: The fluid ounce is widely used in everyday life throughout the United States. In the kitchen, it shows up in recipes for measuring water, milk, oil, and other liquids. You'll also find it on nutrition labels, drink containers, and liquid medicine bottles. Most bottled drinks sold in the U.S., from soda cans to sports drinks, are labeled in fluid ounces.
Outside the kitchen, fluid ounces are also used to measure everyday products like shampoo, lotion, and household cleaners. Packaging labels often list fluid ounces to help shoppers gauge how much liquid is inside each bottle. In pharmacies, you may still see fluid ounces on medication packaging, though many prescriptions now use milliliters for greater accuracy and consistency.
The imperial gallon is a unit of volume used in the imperial measurement system, and it is historically common in the United Kingdom and several other countries. One imperial gallon is equal to 4.54609 liters, which makes it significantly larger than the US gallon (approximately 3.785 liters). It is abbreviated as gal and traditionally used for measuring liquids in larger quantities.
In the imperial system, a gallon is made up of four quarts, eight pints, or 160 imperial fluid ounces. Though the UK has officially adopted the metric system, the imperial gallon is still recognized in specific contexts and remains part of British measurement history. It's most commonly associated with fuel pricing and older food or drink packaging.
Uses: The imperial gallon is most commonly seen today at fuel stations in the UK, where petrol and diesel are still sold by the gallon for pricing comparisons, even though the actual quantity delivered is measured in liters. Historically, the gallon was used for everything from milk deliveries to beer and cider sales.
While modern recipes and packaging have largely shifted to liters and milliliters, the imperial gallon occasionally appears in traditional instructions or product specs, especially for bulk liquids. For those referencing older materials or converting classic measurements, the imperial gallon remains a useful and historically significant unit.
1 fl oz = 0.006505 gal (imp)
Let’s say you want to convert 100 fl oz to gal (imp).
Using the formula:
100 × 0.006505 = 0.651 gal (imp)
So, 100 fl oz is approximately 0.651 gal (imp).
| Fluid Ounce (US) (fl oz) | Gallon (Imperial) (gal (imp)) |
|---|---|
| 1 fl oz | 0.007 gal (imp) |
| 2 fl oz | 0.013 gal (imp) |
| 3 fl oz | 0.02 gal (imp) |
| 4 fl oz | 0.026 gal (imp) |
| 5 fl oz | 0.033 gal (imp) |
| 6 fl oz | 0.039 gal (imp) |
| 7 fl oz | 0.046 gal (imp) |
| 8 fl oz | 0.052 gal (imp) |
| 9 fl oz | 0.059 gal (imp) |
| 10 fl oz | 0.065 gal (imp) |
| 11 fl oz | 0.072 gal (imp) |
| 12 fl oz | 0.078 gal (imp) |
| 13 fl oz | 0.085 gal (imp) |
| 14 fl oz | 0.091 gal (imp) |
| 15 fl oz | 0.098 gal (imp) |