An imperial gallon is exactly 4.54609 liters.
Imperial gallons to Zettaliters Converter — imp gal to ZL
Convert Imperial gallon (imp gal) to Zettaliter (ZL) using the exact conversion factor (1 imperial gallon = 4.54609e-21 zettaliter). See the formula, worked examples, conversion table, history, and common uses.
Imperial gallons to Zettaliters converter
Converter
Volume Converter
Convert metric, US customary, imperial, cooking, dry, and industrial volume units.
Context values
Some unit families need one extra value for a physically accurate result.
Zettaliter is 1e+21 liter units.
Result = input x 0.00454609 / 1e+18.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Imperial gallons to Zettaliters
Imperial gallon and Zettaliter appear side by side at fuel pumps and on beverage labels, since the US measures liquids in gallons while most of the world uses liters. Imperial gallon is most often used for uk fuel and beverage measurement (historically; uk now primarily uses liters for retail).
Formula
zettaliters = imperial gallons × 4.54609e-21
This factor comes from each unit's defined relationship to the category's base unit: 1 imperial gallon equals 0.00454609 base units, and 1 zettaliter equals 1e+18 base units, so dividing one by the other gives the direct imperial gallon-to-zettaliter factor of 4.54609e-21.
Simple example
1 imp gal × 4.54609e-21 = 4.54609e-21 ZL
1 imperial gallon = 4.54609e-21 zettaliters.
Real-world example
10 imp gal × 4.54609e-21 = 4.54609e-20 ZL
10 imperial gallons = 4.54609e-20 zettaliters.
Conversion table
| Imperial gallon (imp gal) | Zettaliter (ZL) |
|---|---|
| 1 imp gal | 4.54609e-21 ZL |
| 5 imp gal | 2.273045e-20 ZL |
| 10 imp gal | 4.54609e-20 ZL |
| 25 imp gal | 1.136523e-19 ZL |
| 50 imp gal | 2.273045e-19 ZL |
| 100 imp gal | 4.54609e-19 ZL |
Reverse conversion: Zettaliter to Imperial gallon
4.54609e-21 ZL × 2.199692e+20 = 1 imp gal
4.54609e-21 zettaliters = 1 imperial gallon.
imperial gallons = zettaliters × 2.199692e+20
For a page dedicated to this direction, see Zettaliter to Imperial gallon.
Understanding the Imperial gallon
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
Where it's used: United Kingdom, Canada (some contexts), and other Commonwealth countries
Imperial gallon vs. US gallon. Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Uses of the Imperial gallon today
- UK fuel and beverage measurement (historically; UK now primarily uses liters for retail)
- Commonwealth country liquid measurement in some contexts
History of the Imperial gallon
The imperial gallon was created by Britain's Weights and Measures Act of 1824, defined as the volume of 10 pounds of water, replacing several inconsistent older English gallon definitions (wine gallon, ale gallon, corn gallon) with one standard.
Historical origin. Imperial gallon was not the invention of a single named person; it developed through the process described above.
Understanding the Zettaliter (ZL)
Zettaliter is 1e+21 liter units.
Imperial gallon — sources
- UK Weights and Measures Act 1824 — Establishes the imperial gallon definition.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many zettaliters are in 1 imperial gallon?
1 imperial gallon equals 4.54609e-21 zettaliters, using the exact defined conversion factor rather than an estimate.
How do I convert imperial gallon to zettaliter?
Multiply the imperial gallon value by 4.54609e-21. The converter above does this instantly to whatever precision you set.
How do I convert zettaliter back to imperial gallon?
Use the reverse factor: 1 zettaliter equals 2.199692e+20 imperial gallons. You can also use the swap control in the converter above to flip the direction instantly.
What is a imperial gallon?
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
What is a zettaliter?
Zettaliter (ZL) is a unit of volume.
Is the imperial gallon to zettaliter conversion exact?
Yes. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between imperial gallon vs. us gallon?
Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Where is the imperial gallon still used today?
United Kingdom, Canada (some contexts), and other Commonwealth countries