Dry-Yeast Pitching Calculator

Enter the original gravity, wort volume, age of yeast, and approximate storage temperature in order to estimate the grams of dry yeast to pitch for ales or lagers:

units:	metric or U.S.customary (e.g. gallons, ounces)
beer type:	ale or lager
original gravity (OG):
wort volume:	XX
age of yeast:	months
storage temperature:	°XX
weight of dry yeast:	0.0

This calculator uses the recommendation from George and Laurie Fix (An Analysis of Brewing Techniques, page 68) of 1.5x10^6 cells per ml and degree Plato for lagers, and half that for ales. It assumes that the dry yeast has 20 billion cells per gram at packaging, and that 4% of the currently-viable cells become unviable every year when stored in a refrigerator (as they should be). When stored at room temperature, 20% of the currently-viable cells become unviable every year. It also assumes (based on very meager evidence) an exponential reduction in viability with temperature, and no viable cells after storage for one year at 40°C (104°F).

Since you're here, I found the following article about rehydrating yeast very interesting: Drayman's Recommendations on Yeast Rehydration. While rehydration may not be necessary for low- or medium-gravity worts, sometimes you want to be sure that you're treating your yeast in the best way possible.

Alcohol Calculator

Enter values for original gravity and final gravity to estimate alcohol by volume in beer:

original gravity (OG):
final gravity (FG):
alcohol (ABV):	0.0%

This calculator uses an equation from Jan DeClerck (provided by Jester Goldman in Beer and Brewing (2016)) to convert from specific gravity to degrees Plato, equation 3b from Anthony Cutaia, Anna-Jean Reid, and R. Alex Speers in Journal of the Institute of Brewing (2009) to convert from original and apparent extract (original and final gravity, in degress Plato) to alcohol by weight, and an equation from Michael Hall in Zymurgy (1995) to convert from alcohol by weight (ABW) to alcohol by volume (ABV). In particular:

OE = -205.347×OG2 + 668.72×OG − 463.37

AE = -205.347×FG2 + 668.72×FG − 463.37

ABW = (0.372 + 0.00357×OE) × (OE − AE)

ABV = ABW × FG / 0.78934