Volumes and losses

The volume waterfall is the least glamorous calculation we do and the one that decides whether the rest are right. Gravity is extract divided by volume. Get the volume wrong and every number downstream is wrong with it.

The waterfall

The waterfall runs in one direction. Strike water and sparge water go in. Grain absorption takes about a liter per kilogram out, less if you squeeze a bag. The mash tun keeps whatever your rig leaves behind. The boil takes a rate per hour, and the wort contracts about four percent as it cools to 20 °C, which is a real volume change and not an accounting one. Then the kettle keeps its deadspace, the hops keep about six milliliters per gram, the chiller and the hoses keep theirs, and the trub keeps the rest.

Every one of those is on your equipment profile, and every one is measurable in an afternoon with a jug. The presets are a starting point, not your rig.

Two distinctions

Deadspace under a false bottom on an all-in-one system is not a loss. The liquid never leaves the kettle, so it is still your wort. Wort that drains nowhere useful out of a mash tun is a loss, and you have to measure out extra water to cover it. The profile keeps the two apart.

A batch size can mean the volume into the fermenter or the volume into the keg, and those differ by the trub. The profile asks which you meant, and the vitals rail shows the whole waterfall so you can see where each liter went.

The beer these numbers come from

Reference pale ale — 20 L into the fermenter, a 60 minute boil.

Grist	Amount	Color
Crisp Maris Otter Pale Ale Malt	4.5 kg	2.8 °L
Thomas Fawcett Caramalt	0.35 kg	9.9 °L

Hops	Amount	Alpha	Addition
Magnum	15 g	13.5 %	60 min boil
Cascade	30 g	6.8 %	10 min boil
Citra	40 g	13 %	20 min stand at 80 °C

It comes out at
Original gravity	1.0507
Final gravity	1.0094
Alcohol	5.52 %
Bitterness	35.66 IBU
Color	5.14 SRM (10.12 EBC)
Into the fermenter	20 L

The numbers

Packaged volume

18.8 L, from volume-waterfall.

strike + sparge − absorption − tun loss − boil-off − shrinkage − kettle losses − trub
⇒ Packaged volume = 18.8 L

Input	Value	Unit
Strike water	13.58	L
Sparge water	16.13	L
Grain absorption	3.88	L
Boil off	2.8	L
Shrinkage	0.92	L
Kettle hop absorption	0.51	L
Volume into fermenter	20	L
Grain	4.85	kg

Sources:

• How to Brew — John J. Palmer, Brewers Publications, 2017