Homebrew recipes and equipment specs mix gallons and litres constantly depending on where they're published, and getting a batch volume conversion slightly wrong compounds into every downstream calculation — strike water, priming sugar, IBU — since all of them take volume as a direct input.
Gallons to litres
| US gallons | Litres |
|---|---|
| 1 | 3.79 |
| 3 | 11.36 |
| 5 | 18.93 |
| 5.5 | 20.82 |
| 6 | 22.71 |
| 10 | 37.85 |
| 15 | 56.78 |
| 20 | 75.71 |
Litres to gallons
| Litres | US gallons |
|---|---|
| 10 | 2.64 |
| 19 | 5.02 |
| 20 | 5.28 |
| 23 | 6.08 |
| 38 | 10.04 |
| 50 | 13.21 |
These figures use the standard 1 US gallon = 3.78541 litres conversion factor, the same constant this site's calculators use internally — every tool on this site (ABV, IBU, priming, dilution and blending, strike water, SRM) that takes a volume input works in litres, so if your recipe or equipment is specified in gallons, this is the conversion step before entering it anywhere.
Why "5 gallons" and "19 litres" aren't quite the same number
A genuine 5 US gallon batch is actually 18.93 L, not the round 19 L this site (and most homebrew literature) uses as a convenient reference figure throughout its examples. The difference (0.07 L, about a third of a cup) is small enough not to matter for any practical brewing calculation, but it's worth knowing the two aren't a perfect match if you're trying to reconcile your own precisely-measured batch volume against a published example that used a rounded number.
UK/Imperial gallons are a different unit entirely
This chart uses US gallons throughout, standard in North American homebrewing. UK (Imperial) gallons are a different, larger unit — 1 UK gallon equals roughly 4.546 litres, about 20% more than a US gallon — so a recipe or equipment spec from a UK source using "gallons" needs a different conversion factor entirely, not this table. If you're working from UK-published measurements, confirm which gallon is meant before converting, since using the US factor on an Imperial-gallon figure understates your actual volume by a meaningful margin.
Using this alongside the calculators
Every tool on this site — ABV, IBU, priming sugar, dilution and blending, strike water, and SRM colour — takes volume in litres. Convert your batch size here first if your recipe or equipment is specified in gallons, or, for US gallons specifically, most calculators' default examples already use a round 19 L (5 gal) figure you can adjust from directly.