Homebrew calculator

How to use it

The numbers at the top are for the recipe; the tabs work on it.

Recipe — batch size into the fermenter, brewhouse efficiency, boil time, all-grain or extract, and the IBU formula. Add fermentables (typical PPG and colour filled in — edit them from your maltster’s sheet), hops (alpha acid from the packet, boil minutes, boil / whirlpool / dry hop) and a yeast (typical attenuation). Start from an example; Save keeps recipes in this browser with JSON export and import.

Mash & water — mash thickness, grain and mash temperatures, boil-off, kettle and tun losses and grain absorption give the strike temperature, mash and sparge water, the pre-boil volume and how big the mash tun must be.

Water chemistry — your water (from the supplier’s report or a test) and a target; tick the salts you have. The tool finds the grams of each that come closest, shows the resulting ions, the sulfate-to-chloride ratio, residual alkalinity and a rough mash pH.

Efficiency — your measured OG, FG and volume: brewhouse efficiency (and Use in the recipe), apparent and real attenuation and ABV.

Carbonation — volumes of CO₂, the beer volume and the warmest temperature it fermented at give the priming sugar (corn sugar, dextrose or table sugar); the keg temperature gives the regulator pressure.

The formulas

Gravity: points = PPG × pounds × efficiency (extract and sugar at 100 %) ÷ gallons. FG from the apparent attenuation; ABV = (OG − FG) × 131.25; real attenuation after Balling.
IBU: Glenn Tinseth’s utilisation 1.65 × 0.000125^(G−1) × (1 − e^(−0.04 t)) ÷ 4.15, or Jackie Rager’s 18.11 + 13.86 tanh((t − 31.32) ÷ 18.27) % with a gravity correction above 1.050 — both at the original gravity. Whirlpool and dry hops count as zero.
Colour: Dan Morey’s SRM = 1.4922 × MCU^0.6859; EBC = 1.97 × SRM. The swatch is an approximate screen colour.
Strike water: John Palmer’s (0.41 ÷ r)(T₂ − T₁) + T₂ (r in L/kg; 0.2 with qt/lb and °F).
Salts: ion contributions from each salt’s formula weight (gypsum 61.5 mg/L calcium and 147 mg/L sulfate per gram per US gallon). Residual alkalinity after Kolbach.
Priming: residual CO₂ = 3.0378 − 0.050062 T + 0.00026555 T² (T °F); sugar from the CO₂ each sugar releases (its formula weight), 1 volume = 1.96 g/L. Keg pressure from the fit to the Zahm & Nagel chart.

The tests check these against worked examples: Palmer’s strike-water example (1.5 qt/lb, 70 °F grain, 150 °F mash → 160.7 °F), Tinseth’s 0.231 utilisation at 1.050 and 60 minutes, the gypsum, calcium chloride, Epsom salt and table salt figures in How to Brew, the familiar 15.2 g of glucose per gallon per volume, and about 11 PSI for 2.5 volumes at 38 °F.

Limits

Ingredient values are typical; use your own maltster’s, hop and yeast data.
The mash pH is a rough model (grist acidity against residual alkalinity, loosely after Kai Troester’s measurements), ±0.2–0.3 at best and often high for dark beers. Measure with a calibrated meter on a cooled sample.
Volumes use rules of thumb for absorption and grain displacement; measure your system.
No style guidelines: the BJCP guidelines are not reproduced here — compare with them yourself.
Bottle only fully fermented beer; above about 3 volumes use heavy bottles.

Linking to an example

A recipe travels packed in the link (?s=…); these can be written by hand:

Parameter Meaning Example

Parameter	Meaning	Example
`example`	One of the example recipes below	`example=dry-stout`
`batch`	Batch size into the fermenter, litres	`batch=23`
`eff`	Brewhouse efficiency, %	`eff=70`

example

One of the example recipes below

example=dry-stout

batch

Batch size into the fermenter, litres

batch=23

eff

Brewhouse efficiency, %

eff=70

example= Shows

`example=`	Shows
`pale-ale`	American pale ale, 20 L (open)
`dry-stout`	Dry stout with roasted barley (open)
`extract-pale`	Extract pale ale with steeped crystal (open)
`pilsner`	German pilsner, 90-minute boil (open)

pale-ale

American pale ale, 20 L (open)

dry-stout

Dry stout with roasted barley (open)

extract-pale

Extract pale ale with steeped crystal (open)

pilsner

German pilsner, 90-minute boil (open)