How to calculate the mash water and sparge, is there a calculator?

The equipment profile is in the app, add the relevant Grainfather equipment. The mash/sparge/water volumes will be calculated accordingly for the brew session.

How much sparge water would I need?

If using to full capacity - 3x Sparge Water Heaters or 1x Sparge Water Heater and a G30 or 2x Sparge Water Heaters and fill one up as soon as empty and rotate.

G30 / G30v3 - Metric - (Grain bill kg x mash thickness L (2.7) ) + 3.5 = Mash water volume in Litres

G30 / G30v3 - Imperial - (Grain bill lbs x mash thickness US Gal (0.34) ) + 0.9 = Mash water volume in US Gallons

G70 / G70v2- Metric - (Grain bill kg x mash thickness L (2.7) ) + 7 = Mash water volume in Litres

G70 / G70v2- Imperial - (Grain bill lbs x mash thickness US Gal (0.34) ) + 1.8 = Mash water volume in US Gallons