Last week I talked about the batch sparging technique as presented by John Palmer’s How to Brew, and noted that because of the loss in extract potential due to the technique (as compared to “normal” all-grain recipes), that Palmer provides calculations to help you scale up your recipe’s grain bill to accommodate for that loss in extract potential.
I promised this week that I would publish a browser-based calculator that implements Palmer’s formulas, and that’s what I’ve done: you can find the calculator here.
How to use it is, plug in the inputs from your “regular” recipe that you want to adjust for batch sparging:
- Your target gravity (e.g. 1.050)
- The recipe’s grain bill weight in pounds
- The batch volume (e.g. 5 gallons)
- The boil volume (e.g. 6 gallons)
- (The “Water-retention coefficient” is a magic number Palmer gives that you can fiddle with if you like)
Click “Calculate” and the outputs will be calculated. In particular, the numbers you’ll want are the new grain bill (weight) and the volume of water you’ll need for the mash.
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