Gallons to Liters Converter

US gallons to liters — quick reference

The formula

A US gallon is exactly 3.785411784 liters, so US gallons to liters is a single multiply by that exact number:

liters = US gallons × 3.785411784

Worked example with the default: 15 × 3.785411784 = 56.78 L.

The “× 4” shortcut runs slightly high (the real factor is 3.785), so it’s a good “at least this big” estimate for sizing a container, but use the exact factor when you need true capacity. And keep to the US gallon — the imperial gallon is 4.546 L.

How to use the gallons to liters converter

This is the conversion for taking a US-gallon figure and expressing it in liters — scaling a US recipe for metric measuring jugs, reading a tank or appliance spec to a metric audience, or sizing imported equipment that’s rated in liters. Enter US gallons, read liters; Swap reverses it. The gallon here is the US gallon (3.785 L), not the larger imperial one.

Recipes and home brewing are a frequent case. A 5-gallon batch is 18.93 liters, and a 1-gallon jug is 3.79 liters — handy when your fermenter, stockpot, or measuring equipment is graduated in liters. Converting once and marking the liter level saves re-deriving it every brew day.

Tank and equipment specs are the other driver. A 15-gallon aquarium is 56.78 liters, a 40-gallon water heater is 151.4 liters, and a fuel tank rated “15 gallons” is about 56.8 liters at the foreign pump. Because filters, heaters, and stands abroad are sized in liters, the liter figure is the one that matches what you can actually buy.

For a fast estimate, multiply gallons by four — slightly over the true 3.785 — so 15 gallons is “about 60 liters,” a bit above the exact 56.78. The shortcut reads high, which is the safe direction when you’re making sure a container is big enough; use the exact factor when you need the real capacity rather than a ceiling.

Frequently asked questions