Understanding Acre-Feet to Imperial Gallons Conversion
The acre-foot is a US customary volume of roughly 1,233.48 cubic metres, dominant in US water management. An Imperial gallon is a UK unit equal to exactly 4.54609 litres, about 20 percent larger than the US gallon. Using the Imperial gallon yields fewer gallons per acre-foot than the US gallon would. This conversion is used when converting acre-foot water volumes into UK Imperial gallons.
Conversion Formula
To convert Acre-Feet to Imperial Gallons, multiply the number of Acre-Feet by this factor:
Step-by-Step Example
Convert 25 Acre-Feet to Imperial Gallons.
Write the formula:
Substitute the value:
Calculate the result:
How to Convert Acre-Feet to Imperial Gallons
Use the fixed factor between Acre-Feet and Imperial Gallons to scale any value.
- Find the factor: One Acre-Foot equals 271328 Imperial Gallons.
- Enter your value: Take the amount in Acre-Feet you want to convert.
- Multiply: Multiply your Acre-Feet value by 271328 to get Imperial Gallons.
- Read the result: For example, 25 Acre-Feet gives about 6783200 Imperial Gallons.
Acre-Feet to Imperial Gallons conversion table
| Acre-Feet (acre-foot) | Imperial Gallons (imp-gal) |
|---|---|
| 0 | 0 |
| 1 | 271328.1 |
| 2 | 542656.1 |
| 3 | 813984.2 |
| 4 | 1085312 |
| 5 | 1356640 |
| 6 | 1627968 |
| 7 | 1899297 |
| 8 | 2170625 |
| 9 | 2441953 |
| 10 | 2713281 |
| 15 | 4069921 |
| 20 | 5426561 |
| 25 | 6783202 |
| 30 | 8139842 |
| 40 | 10853120 |
| 50 | 13566400 |
| 60 | 16279680 |
| 70 | 18992970 |
| 80 | 21706250 |
| 90 | 24419530 |
| 100 | 27132810 |
| 150 | 40699210 |
| 200 | 54265610 |
| 250 | 67832020 |
| 300 | 81398420 |
| 400 | 108531200 |
| 500 | 135664000 |
| 600 | 162796800 |
| 700 | 189929700 |
| 800 | 217062500 |
| 900 | 244195300 |
| 1000 | 271328100 |
| 2000 | 542656100 |
| 3000 | 813984200 |
| 4000 | 1085312000 |
| 5000 | 1356640000 |
| 10000 | 2713281000 |
| 25000 | 6783202000 |
| 50000 | 13566400000 |
| 100000 | 27132810000 |
| 250000 | 67832020000 |
| 500000 | 135664000000 |
| 1000000 | 271328100000 |
Which gallon do you mean?
“gallon” means different units by region. This page uses the Imperial gallon (UK). 1 Acre-Feet in each:
| Definition | Result |
|---|---|
| US gallon 3.785 L | 325851.4 gal |
| Imperial gallon (UK) 4.546 L | 271328.1 imp-gal (this page) |
What is the Acre-Foot?
The acre-foot is a unit of volume equal to the amount of water needed to cover one acre of land to a depth of one foot. It is the standard measure used for large-scale water resources in the United States, including reservoirs, irrigation supplies, and municipal water rights.
Definition
One acre-foot is defined as the volume of a prism with a base area of one acre (43,560 square feet) and a height of one foot, giving exactly 43,560 cubic feet.
Because the US survey foot and the international foot differ slightly, the acre-foot is fixed by its exact defining relation of 43,560 cubic feet, which equals about 1,233.48 cubic metres or 1,233,482 litres.
Origin and History
The acre-foot arose in the American West during the late 19th and early 20th centuries, as irrigation districts and water agencies needed a practical unit for measuring large volumes of stored and delivered water. It combines the acre, an old English unit of land area, with the foot of depth, making it intuitive for engineers estimating how much water a given area of reservoir or flooded field holds.
Law and Notable Facts
The acre-foot remains the legal and administrative unit for water rights, reservoir capacity, and interstate water compacts throughout the western United States. A commonly cited rule of thumb is that one acre-foot supplies roughly one to two typical American households for a year, which is why it is used to describe how many homes a reservoir can serve.
Real-World Examples and Conversions
- A single acre-foot equals about 325,851 US gallons of water.
- Lake Mead, the largest reservoir in the US, has a capacity of roughly 28.9 million acre-feet when full.
- An Olympic swimming pool holds about 2,500 cubic metres, or roughly 2 acre-feet.
- In metric terms, 1 acre-foot is approximately 1,233 cubic metres (1.23348 million litres).
What is the Imperial Gallon?
The imperial gallon is a unit of volume used in the United Kingdom and several Commonwealth countries, most commonly for measuring fuel, beverages, and other liquids. It is noticeably larger than the US gallon.
Definition
The imperial gallon is defined as exactly 4.54609 litres:
This is an exact defining relation, not an approximation. The imperial gallon is also subdivided into 4 quarts, 8 pints, or 160 imperial fluid ounces, and it is about 20% larger than the US liquid gallon (3.78541 L).
Origin and History
The gallon descends from medieval English measures for wine and ale, which historically had several conflicting definitions. The imperial gallon was standardised by the British Weights and Measures Act of 1824, originally defined as the volume of 10 pounds of distilled water weighed in air at 62 °F. In 1985 the UK redefined it in exact metric terms as 4.54609 litres, aligning the traditional unit with the SI system.
Law and Notable Facts
The imperial gallon remains a legally recognised unit in the UK and countries such as Canada, though metric litres are now standard for most trade. A key point of confusion is that the imperial gallon (4.54609 L) differs from the US liquid gallon (3.785411784 L); the two share a name but are distinct units, so fuel-economy figures quoted in "miles per gallon" are not directly comparable between the UK and the US.
Real-World Examples and Conversions
- A UK fuel purchase of 10 imperial gallons is about 45.46 litres.
- A car rated at 50 miles per imperial gallon achieves roughly 41.6 miles per US gallon for the same efficiency.
- 1 imperial gallon of fresh water weighs about 4.546 kg (roughly 10 pounds), reflecting its original 1824 definition.
- 1 imperial gallon equals about 1.20095 US gallons.
Frequently Asked Questions
What is the formula to convert Acre-Feet to Imperial Gallons?
Multiply the number of Acre-Feet by 271328. In symbols, imp-gal = acre-foot × 271328.
How many Imperial Gallons are in 1 Acre-Foot?
One Acre-Foot equals 271328 Imperial Gallons. Conversely, one Imperial Gallon equals about 3.68558 × 10⁻⁶ Acre-Feet.
How do I convert 10 Acre-Feet to Imperial Gallons?
Multiply 10 by 271328, which gives 2713280 Imperial Gallons.
What should I know about the Imperial Gallon in this conversion?
The Imperial gallon (4.54609 L) is larger than the US gallon (about 3.785 L).
Where is the Acre-Feet-to-Imperial Gallons conversion useful?
It is useful when converting acre-foot water volumes into UK Imperial gallons, letting you compare a large US water volume with Imperial Gallons.