Imperial Gallons to Gallons Converter - Convert UK gal to US gal Instantly
Convert Imperial gallons (UK gal) to US gallons (gal) quickly and accurately with this easy-to-use volume converter. Ideal for brewing, fuel planning, aquariums, beverage packaging, logistics, and engineering tasks that require precise conversions between UK and US gallon standards.
Note: This tool converts Imperial (UK) gallons to US liquid gallons. If you need UK gal ↔ liters or US gal ↔ liters, use the dedicated tools for those conversions.
About Imperial Gallons (UK) to US Gallons Conversion
Imperial gallons (UK gal) and US gallons (gal) both measure liquid volume, but they are defined differently. The Imperial gallon is larger—exactly 4.54609 liters—while a US gallon is 3.785411784 liters. As a result, any value in UK gallons converts to a larger number in US gallons. This page uses the exact liter-based ratio so your conversions are consistent with engineering references, audit trails, and regulatory documents.
Converting via liters is robust and transparent. Since both gallon definitions are tied to liters, applying the exact constants helps avoid rounding drift and unit confusion when working across UK, US, and metric specifications in brewing, transportation, aquaculture, and packaging.
Conversion Formula
Use the exact liter-based ratio:
US gal = UK gal × (4.54609 ÷ 3.785411784) ≈ UK gal × 1.200949Example:
10 UK gal = 10 × (4.54609 ÷ 3.785411784) = 12.00949 US gal
To reverse the operation:
UK gal = US gal ÷ (4.54609 ÷ 3.785411784) = US gal × 0.832674.
Imperial vs US Gallons
The Imperial gallon is primarily referenced in the United Kingdom and certain maritime or historical contexts. The US gallon is widely used in the United States for fuel, beverages, and consumer goods. The ~20% difference (4.54609 L vs 3.785411784 L) makes it essential to specify which gallon appears in your data, especially in recipes, dosing schedules, tank-sizing, and compliance reporting.
Why Convert UK gal to US gal?
- 🍺 Brewing & distilling: Translate UK batch sizes to US documentation.
- ⛽ Fuel & transport: Compare tank specs or logs across regions.
- 🐠 Aquaculture & aquariums: Align treatment dosing with US unit requirements.
- 🥤 Beverage packaging: Prepare labels and production notes for US markets.
- 📦 Logistics & compliance: Convert legacy UK gallon specs into US gallons for audits.
Common Conversions
- 1 UK gal = 1.20095 US gal
- 2 UK gal = 2.40190 US gal
- 5 UK gal = 6.00475 US gal
- 10 UK gal = 12.00949 US gal
- 20 UK gal = 24.01898 US gal
- 50 UK gal = 60.04746 US gal
- 100 UK gal = 120.09492 US gal
What is an Imperial (UK) Gallon?
The Imperial gallon is a UK unit of liquid volume defined as exactly 4.54609 liters (160 Imperial fluid ounces). It appears in brewing, maritime documentation, and historical specifications. Although modern UK retail typically uses liters for labeling, UK gallons are still used in technical and enthusiast communities.
What is a US Gallon?
The US gallon is a customary unit of liquid volume used widely in the United States. It is defined as 231 cubic inches, which corresponds to exactly 3.785411784 liters. You’ll often see US gallons in fuel sales, beverage containers, and product specs.
Step-by-Step: Converting UK gal to US gal
- Write down your volume in Imperial (UK) gallons.
- Multiply by 4.54609 ÷ 3.785411784 (≈ 1.200949).
- Express the result in US gal (US gallons).
Example walkthrough:
Input: 7.5 UK gal
Multiply: 7.5 × (4.54609 ÷ 3.785411784) = 9.00712
Output: 9.00712 US galPrecision, Rounding & Significant Figures
Five decimal places are more than sufficient for everyday use. In technical reporting, match your precision to sensors and standards. Keep significant figures consistent across chained calculations to minimize rounding error and ensure reproducibility.
Use Cases of UK gal → US gal
- 🍻 Converting UK-oriented brew volumes to US specifications
- 🚚 Preparing shipping paperwork that requires US gallons
- 🐟 Translating aquaculture dosing from UK references to US units
- 🥫 Adjusting packaging/labels for US markets from UK formulations
- 🧪 Updating SOPs and lab notes from Imperial to US customary units
Quick Reference Table
| Imperial Gallons (UK gal) | US Gallons (gal) |
|---|---|
| 1 | 1.20095 |
| 2 | 2.40190 |
| 5 | 6.00475 |
| 10 | 12.00949 |
| 20 | 24.01898 |
| 50 | 60.04746 |
Frequently Asked Questions
How do you convert Imperial gallons to US gallons?
Multiply Imperial gallons by the exact ratio 4.54609 ÷ 3.785411784. In other words: US gal = UK gal × (4.54609 / 3.785411784) ≈ UK gal × 1.200949.
How many US gallons are in 1 Imperial gallon?
1 Imperial gallon ≈ 1.20095 US gallons. The ratio comes from 4.54609 L per UK gal divided by 3.785411784 L per US gal.
Why are Imperial and US gallons different sizes?
They originate from different historical standards. An Imperial (UK) gallon is exactly 4.54609 liters, while a US gallon is exactly 3.785411784 liters—making the UK gallon about 20% larger.
How do I convert US gallons back to Imperial gallons?
Divide by the same ratio: UK gal = US gal ÷ (4.54609 / 3.785411784) = US gal × 0.832674. You can also convert both via liters if preferred.
Is this for liquid gallons?
Yes. This tool converts liquid volume using the exact liter definitions for US and Imperial (UK) gallons.
Tips for Working Across Gallon Systems
- Always label which gallon system you’re using—US or Imperial.
- Include the exact liter factors (4.54609 and 3.785411784) in technical notes for reproducibility.
- For small volumes, consider converting to liters or milliliters to simplify dosing and measurement.