Instantly Convert Imperial Gallons ↔ Litres — Both Directions
Convert Imperial gallons to litres (gal → L) or litres to Imperial gallons (L → gal) instantly. Get the exact conversion with formula breakdown, reference table, and real-world examples — all free, no sign-up needed.
The Imperial gallon and the litre are both units of volume — one from the British imperial system, one from the metric. Our converter handles both directions instantly and accurately using the exact defined value of 1 Imperial gallon = 4.54609 litres — no approximation required.
The Imperial gallon (gal) is a unit of volume used primarily in the United Kingdom, Canada, and some Commonwealth countries. Since 1985, the Imperial gallon has been defined as exactly 4.54609 litres. It is used for measuring fuel consumption, liquid volume in brewing, and bulk liquid trade. Note: the US gallon is a different, smaller unit — only 3.78541 litres — so always confirm which gallon is being used.
The litre (L) is the metric unit of volume used across most of the world for everyday liquid measurement — from bottled water and milk to fuel and cooking. One litre is defined as exactly 1 cubic decimetre (dm³), or 1,000 cubic centimetres. It is not an SI base unit but is accepted for use with the SI system. One litre of water has a mass of approximately 1 kilogram at 4°C.
The exact conversion factor is 1 Imperial gallon = 4.54609 litres, as defined by the Weights and Measures Act 1985 (UK). This is a precise legal definition, not an approximation. For the reverse, 1 litre = 0.219969 Imperial gallons (= 1 ÷ 4.54609). All conversions on this page use these exact values.
Choose a direction, enter your value, and get an instant conversion
The conversion between Imperial gallons and litres is based on an exact legal definition. Since 1985, the UK Weights and Measures Act defined the Imperial gallon as precisely 4.54609 litres — making all conversions in both directions mathematically exact with no estimation involved.
The table below lists commonly needed Imperial gallon-to-litre conversions. All values use the exact factor of 1 Imperial gallon = 4.54609 litres. For litres to gallons, divide the litre value by 4.54609 or use the converter above.
| Imperial Gallons (gal) | Litres (L) | Millilitres (mL) | US Gallons (US gal) | Common Context |
|---|---|---|---|---|
| 0.25 gal | 1.1365 L | 1,136.5 mL | 0.3002 US gal | Large glass of water |
| 0.5 gal | 2.2730 L | 2,273.0 mL | 0.6005 US gal | Half-gallon carton |
| 1 gal | 4.5461 L | 4,546.1 mL | 1.2009 US gal | Standard Imperial gallon |
| 2 gal | 9.0922 L | 9,092.2 mL | 2.4019 US gal | Small fuel can |
| 3 gal | 13.638 L | 13,638 mL | 3.6028 US gal | Typical watering can |
| 4 gal | 18.184 L | 18,184 mL | 4.8038 US gal | Large bucket |
| 5 gal | 22.730 L | 22,730 mL | 6.0047 US gal | Jerry can / small tank |
| 8 gal | 36.369 L | 36,369 mL | 9.6076 US gal | Medium fuel tank |
| 10 gal | 45.461 L | 45,461 mL | 12.009 US gal | Small car fuel tank |
| 15 gal | 68.191 L | 68,191 mL | 18.014 US gal | Mid-size car tank |
| 20 gal | 90.922 L | 90,922 mL | 24.019 US gal | Large car / SUV tank |
| 50 gal | 227.305 L | 227,305 mL | 60.047 US gal | Drum / storage barrel |
| 100 gal | 454.609 L | 454,609 mL | 120.095 US gal | Large water butt |
| 500 gal | 2,273.05 L | 2,273,050 mL | 600.47 US gal | Intermediate bulk container |
| 1,000 gal | 4,546.09 L | 4,546,090 mL | 1,200.95 US gal | Small storage tank |
Need to convert the other way? The table below shows common litre values converted to Imperial gallons. All values use the exact factor of 1 litre = 0.219969 Imperial gallons (= 1 ÷ 4.54609).
| Litres (L) | Imperial Gallons (gal) | Imperial Pints (pt) | US Gallons (US gal) |
|---|---|---|---|
| 1 L | 0.21997 gal | 1.7598 pt | 0.26417 US gal |
| 2 L | 0.43994 gal | 3.5195 pt | 0.52834 US gal |
| 5 L | 1.0998 gal | 8.7988 pt | 1.3209 US gal |
| 10 L | 2.1997 gal | 17.598 pt | 2.6417 US gal |
| 20 L | 4.3994 gal | 35.195 pt | 5.2834 US gal |
| 25 L | 5.4992 gal | 43.994 pt | 6.6043 US gal |
| 40 L | 8.7988 gal | 70.390 pt | 10.567 US gal |
| 50 L | 10.998 gal | 87.988 pt | 13.209 US gal |
| 60 L | 13.198 gal | 105.59 pt | 15.850 US gal |
| 75 L | 16.498 gal | 131.98 pt | 19.813 US gal |
| 100 L | 21.997 gal | 175.98 pt | 26.417 US gal |
| 200 L | 43.994 gal | 351.95 pt | 52.834 US gal |
| 500 L | 109.985 gal | 879.88 pt | 132.086 US gal |
| 1,000 L | 219.969 gal | 1,759.8 pt | 264.172 US gal |
The Imperial gallon-to-litre conversion appears across a wide range of everyday situations — from fuel and cooking to agriculture, brewing, and international trade. Here are the most common real-world scenarios where this conversion is essential.
Fuel consumption in the UK is often expressed in miles per gallon (mpg) using the Imperial gallon, while most other countries use litres per 100 km. Converting between the two systems is essential when comparing vehicles or reading foreign spec sheets. A car doing 40 mpg (Imperial) uses 7.07 litres per 100 km. A full 50-litre tank holds approximately 11 Imperial gallons.
UK and Irish breweries traditionally measure batch sizes in Imperial gallons. Converting to litres is essential when scaling recipes, ordering ingredients in metric quantities, or exporting to metric markets. A standard UK firkin (cask) holds 9 Imperial gallons = 40.91 litres. Home brewers frequently need this conversion when adapting recipes between British and metric formats.
Irrigation systems, fertiliser mixing rates, and pesticide dilutions in the UK are often specified in Imperial gallons, while modern equipment displays in litres. Converting accurately is critical to avoid over- or under-dosing crops. For example, a field measured in acres may have irrigation specified as gallons per acre, needing conversion to litres for metric equipment.
Pool volumes in the UK are often quoted in Imperial gallons on older equipment and documentation, while chemical dosing instructions use litres. Converting is necessary for accurate chemical treatment. A standard domestic swimming pool holds approximately 20,000 Imperial gallons = 90,922 litres. Water butts and storage tanks are similarly affected.
Older British recipe books and catering guides use Imperial gallons for large-batch cooking — soups, stocks, and sauces at scale. Modern kitchens and food safety guidelines use litres. Converting accurately ensures consistent recipe results. For example, 1 Imperial gallon of stock = 4.546 litres — filling approximately 4.5 standard litre containers.
Ship fuel capacity, tank specifications, and liquid cargo manifests historically used Imperial gallons in UK shipping. International trade documents increasingly require metric (litre) values. Customs declarations, ISO container liquid volumes, and international petroleum trading all require accurate gallon-to-litre conversion. 1,000 Imperial gallons = 4,546.09 litres — important at scale.
The UK Weights and Measures Act 1985 provides the legal definition of the Imperial gallon as exactly 4.54609 litres. This is the authoritative source for all Imperial volume unit definitions used in the United Kingdom.
View Legislation →The Bureau International des Poids et Mesures defines the litre as an accepted non-SI unit equal to exactly 1 cubic decimetre (dm³). Their SI brochure is the definitive international reference for all metric unit definitions.
Visit BIPM →Need to convert other volume units? Explore our full collection of free volume converters at ConcreteMetric — covering US gallons, pints, quarts, cubic metres, and more, all with exact formulas and reference tables.
Explore All →