Mash Water Ratio Calculator
In all-grain brewing, the strike water volume is set by your grain weight and the mash thickness ratio you choose. This calculator multiplies the grain weight by your ratio in quarts per pound and returns the strike water in quarts, gallons and litres, plus the equivalent metric ratio in litres per kilogram. A typical mash runs around 1.25 to 1.5 quarts per pound. Adjust the ratio to suit your recipe and equipment, then measure the strike water it gives you.
Mash water formula
strike water (qt) = grain (lb) * ratio (qt/lb)
gallons = quarts / 4
litres = quarts * 0.946352946
ratio (L/kg) = ratio (qt/lb) * 2.0863
Strike water is grain weight times the mash thickness ratio. There are 4 quarts in a US gallon, and one US quart is about 0.9464 litres. The metric ratio uses the quart-to-litre and pound-to-kilogram conversions.
Worked example
- 10 lb of grain at 1.25 quarts per pound.
- Strike water = 10 times 1.25 = 12.5 quarts.
- That is 12.5 / 4 = 3.125 US gallons.
- In litres, 12.5 times 0.9464 = about 11.83 litres.
- The ratio 1.25 qt/lb equals about 2.61 litres per kilogram.
Mash water ratio: frequently asked questions
What is the mash water to grain ratio?
It is the volume of strike water you use per unit weight of grain, which sets the mash thickness. In US units it is quarts of water per pound of grain; in metric it is litres per kilogram. A common range is 1.25 to 1.5 quarts per pound, equivalent to about 2.6 to 3.1 litres per kilogram.
How do I find my strike water volume?
Multiply the grain weight by your chosen ratio. For 10 pounds of grain at 1.25 quarts per pound you need 12.5 quarts. This calculator also converts that to gallons and litres so you can measure with whatever vessel you have.
Does mash thickness affect the beer?
It can. A thicker mash (less water per pound) is sometimes used for protein-rich grists and can favour certain enzyme activity, while a thinner mash is easier to stir and can aid conversion. Many brewers use around 1.3 quarts per pound as a balanced default and adjust to their system.
How do quarts per pound and litres per kilogram relate?
Multiply quarts per pound by about 2.086 to get litres per kilogram, because one quart is about 0.946 litres and one pound is about 0.454 kilograms. So 1.25 quarts per pound is roughly 2.61 litres per kilogram. This calculator reports both.
Official sources
- NIST: US to metric volume and mass conversions.
- The strike water is a grain weight times ratio calculation, arithmetic by definition.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.