Gallons to Liters Converter - Free Online Tool

Convert gallons to liters instantly. 1 gallon (US) = 3.78541 liters. Fast, accurate volume conversion. No signup, works offline.

Quick Reference

US Gallons	Liters	Context
1 gal	3.79 L	Milk jug
5 gal	18.93 L	Water cooler bottle
10 gal	37.85 L	Aquarium
15 gal	56.78 L	Typical car fuel fill-up
20 gal	75.71 L	Large fuel tank
50 gal	189.27 L	Hot water heater

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Frequently Asked Questions

Multiply gallons by 3.78541 to get liters. The formula is: liters = gallons × 3.78541. This conversion factor comes from the legal definition that 1 US liquid gallon = exactly 231 cubic inches, which equals 3.78541178 liters.

Converting fuel tank capacity when buying imported vehicles, understanding US recipe measurements in metric kitchens, calculating paint or chemical quantities for international shipping, comparing fuel prices between US and metric countries, sizing water heaters and tanks, and working with industrial fluid volumes.

Historical trade practices created regional variations. The US gallon (3.785L) derives from the wine gallon, standardized in 1832. The UK imperial gallon (4.546L) comes from the ale gallon, defined as 10 pounds of water in 1824. After US independence, the two systems diverged. Canada officially uses liters now but some older references use imperial gallons.

For fuel calculations and recipes, 2 decimal places (e.g., 37.85L) is standard. For commercial transactions and industrial applications, 2-3 decimal places ensure accuracy. For scientific laboratory work, use 4-5 decimal places. For quick estimates (tank sizing), rounding to the nearest liter is often sufficient.

Remember: 1 gallon = 4 quarts. So 1 quart = 0.946 liters, and 1 gallon = 3.785 liters. To convert: gallons × 4 = quarts; quarts × 0.946 = liters; or directly: gallons × 3.785 = liters. Example: 2.5 gallons = 10 quarts = 9.46 liters.

A 5-gallon bucket holds 18.93 liters of paint. A 15-gallon car gas tank is 56.78 liters. A 50-gallon water heater holds 189.27 liters. A 10-gallon aquarium is 37.85 liters. A gallon of milk (128 fl oz) is 3.785 liters. A half-gallon ice cream container is 1.89 liters.

Completely private. This tool performs all calculations in your web browser using JavaScript. No gallon values are uploaded to servers, logged, or shared. The converter works offline once the page loads, ensuring your volume measurements never leave your device.

For batch conversions, spreadsheet software is ideal. In Excel or Google Sheets, enter gallon values in column A and use the formula =A1*3.78541 in column B. Drag the formula down to convert hundreds of values instantly. This is much more efficient than single conversions for large datasets.

Chemical manufacturing and distribution (international shipping), automotive industry (fuel systems, engine coolants), agriculture (fertilizer and pesticide application), food and beverage production (recipe scaling), petroleum industry (fuel trading), paint and coatings (product specifications), and aquaculture (tank sizing and water chemistry).

Round rule: 1 gallon ≈ 4 liters (slightly overstates by 5%). For better accuracy, remember 1 gallon ≈ 3.8 liters. Mental shortcut: multiply gallons by 4, then subtract 5%. Example: 10 gallons × 4 = 40, minus 5% (2) = 38 liters (actual: 37.85L). Or simply remember: 'almost 4 liters per gallon'.

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