Work out mash water volume instantly with clear inputs, formula shown and shareable results.
Strike water is grain weight times mash thickness, typically 2.5-3.5 litres per kilogram. Grain retains around 1 litre per kilogram, and the tun's dead space holds more, so first runnings are always well below the water added. Grain itself occupies about 0.67 litres per kilogram, which sets the tun volume needed.
Strike water
Strike water = grain weight x mash thickness
Runnings
First runnings = strike water - grain absorption x grain weight - dead space
Yes. Thicker mashes favour beta-amylase and produce more fermentable wort with better protein degradation; thinner mashes favour alpha-amylase and extract more efficiently.
With crush, husk content and how thoroughly the grain bed is drained. Measure your own figure by mass balance over several brews rather than assuming a book value.