# Basic Brewing Math

Brewing does involve plenty of math, but for the most part, it’s a practical kind of math. Brewing math is focused primarily on the concentration of sugars in water, which tells us how much alcohol is likely to be created from fermentation.

## A Gallon of Water

• There are 128 ounces in a gallon
• 64 ounces in a half gallon (large growler)
• 32 ounces in a quart (small growler)
• There are four cups in a quart
• There are four quarts in a gallon

## How Much Does Water Weigh?

A gallon of water weighs just over 8 pounds, so when buying a kitchen scale to weigh material, look for one whose max weight is 10 pounds or so. You’ll be surprised how often you want a precise number of ounces or gallons of water when you’re brewing. (8.34 is the technical answer, so maybe “8-and-one-third-pounds” is more accurate.)

## 20L Kettle?

Kettles and coolers are usually described in liters, like a “20 liter stainless steel kettle.” Liters and quarts are roughly comparable, so your 20 liter stainless steel kettle = 20 qt / 4 (quarts in a gallon) = 5 gallons when full. This is certainly usable for brewing tasty beer, but if you’re making the investment, a larger kettle volume will give you the ability to do full volume boils. This gives you more control over color and can make transfers simpler.

## Hydrometers, LME, and DME

Hydrometers, while not strictly necessary, give the brewer useful information about the amount of alcohol the wort + yeast can produce.

One pound of liquid malt extract per gallon will produce a gravity slightly below 1.040. Liquid malt extract – LME – is usually sold in 3.3 pound cans or jars.

One pound of dry malt extract per gallon will produce a gravity just above 1.040. Dry malt extract – DME – is usually sold in one pound or three pound bags for the home brewer’s use.

Stacie