Reference formulas
From fundamentals to full brew-day math
Every formula below is translated to English and paired with an instant calculator. Use metric inputs (kg, liters, degrees Plato, EBC) for consistent results.
Measurements
Quick references for classic brewing units.
Plato (°P)
1 °P = 1 gram of sugar per 100 grams of wort.
Plato: — °P
EBC color
1 EBC = 1 ml of iodine in 100 ml of water.
Reference only (no calculator required).
Brewhouse efficiency
Estimate theoretical extract and compare to your real brew.
100% brewhouse efficiency
(Extract from malt 1 + extract from malt 2 + …) / total liters = grams of sugar per liter.
Plato at 100%: — g/L
Actual brewhouse efficiency
Measured Plato of the wort ÷ Plato at 100% efficiency.
Efficiency: —%
Beer color (Morey)
Calculate color per fermentable and turn it into a final EBC value.
| Ingredient | Weight (kg) | Color (EBC) | Volume (L) | A value |
|---|
Formula per ingredient
A = (4.236 × M × K) / V
M = kg, K = EBC, V = liters.
Final beer color
Beer color = 2.9353 × (SA)0.69
SA = sum of all A values.
Water calculations
Plan volumes from mash to kettle.
Evaporation
Evaporation = boil time × evaporation per hour
Evaporation: — L
Mash water
Mash water = mash thickness × grain bill
Mash water: — L
Sparge water
Sparge water = target post-boil volume - mash water + 1.01 × malt kg + evaporation
Sparge water: — L
Total brewing water
Total water = mash water + sparge water
Total water: — L
Strike water temperature
Estimate the water temperature needed before adding grain.
Formula
Ts = [ (M × 1.6 × (T1 - Tm)) / (V × 4.18) ] + T1 + 3
"+3" is a kettle heat loss correction. Adjust for your system.
Strike water temperature: — °C
Hop formulas
Work backwards from IBU targets or check your bitterness.
How much hops to use?
Grams of hops = (Liters of wort × 4 × IBU) / (Alpha acid % × 10)
Required hops: — g
Substitute hop
Replacement hops = (Alpha % original × grams original) / Alpha % substitute
Replacement grams: — g
IBU from hop amount
IBU = (grams of hops × alpha % × 10) / (liters of wort × 4)
Estimated IBU: —
Bitterness index
BI = IBU / (SG - 1.000)
Bitterness index: —
Yeast attenuation
Estimate final gravity from yeast attenuation.
Formula
Final SG = Start SG - Attenuation × (Start SG - 1.000)
Enter attenuation as a percentage from the yeast spec sheet.
Final SG: —
What is missing compared to a full brewing toolkit?
- ABV and ABW calculators based on OG/FG.
- Carbonation and priming sugar calculations.
- SRM ↔ EBC conversions and color chart previews.
- Yeast pitch rate (cells per ml per °P).
- Water chemistry adjustment targets (sulfate/chloride ratios).
We can add these next if you want a complete brewing workbook.