zymurgy

A small TypeScript library of utilities for estimating beer and wine fermentation.

Published as @jbaran/zymurgy. There are no runtime dependencies.

Install

npm install @jbaran/zymurgy

Usage

const {
  brixToSG,
  sgToBrix,
  platoToSG,
  sgToPlato,
  sgToPoints,
  pointsToSG,
  abv,
  abvAlternate,
  apparentAttenuation,
  correctHydrometerSG,
  predictedOG,
  predictedFG,
  tinsethIBU,
  moreySRM,
  maltColorUnits,
  strikeTemperatureF,
  residualAlkalinity,
  saltIonDelta,
  lacticAlkalinityDrop,
  troesterMashPH,
  blendWater,
} = require('@jbaran/zymurgy');

brixToSG(10);                      // 1.04
sgToBrix(1.04);                    // 10
platoToSG(12);                     // 1.048
sgToPlato(1.048);                  // 11.9
sgToPoints(1.040);                 // 40
abv(1.050, 1.010);                 // 5.3
abvAlternate(1.060, 1.012);        // 6.5
apparentAttenuation(1.050, 1.010); // 80
correctHydrometerSG(1.050, 80);    // 1.052  (80 °F sample, 60 °F hydrometer)
predictedOG([{ amountLb: 10, ppg: 36 }], 75, 5); // 1.054
predictedFG(1.050, 80);            // 1.01
tinsethIBU([{ massG: 30, alphaAcidPercent: 6, timeMin: 60, use: 'boil', form: 'whole' }], 1.040, 20); // 22.7
moreySRM(maltColorUnits(10, 8, 5)); // 10
strikeTemperatureF(152, 70, 1.25); // 165.1
residualAlkalinity({ca: 50, mg: 10, na: 0, cl: 0, so4: 0, alkalinity: 50}); // 34.3
saltIonDelta('gypsum', 1, 1).ca;   // 61.5  (CaSO4·2H2O, 1 g per gal)
lacticAlkalinityDrop(1, 1, 88);    // 155.6 ppm as CaCO3
troesterMashPH(0, 2);              // 5.57  (RA 0, 2 SRM, 4 L/kg)
blendWater({ca: 100, mg: 20, na: 40, cl: 60, so4: 80, alkalinity: 120}, 0.5).ca; // 50

These are brewing estimates, not lab-grade measurements. Specific gravity is rounded to 3 decimal places, Brix and Plato to 1, gravity points to the nearest integer, ABV / attenuation / IBU / SRM / EBC to 1 decimal, volumes to 3, strike temperature to 1, ion / RA / lactic alkalinity-drop ppm to 1, and mash pH to 2. Related conversions are not always exact inverses.

API

Gravity

brixToSG(brix: number): number

Converts degrees Brix to specific gravity.

| Brix | SG | |------|-------| | 0 | 1.000 | | 1 | 1.004 | | 10 | 1.040 | | 20 | 1.083 | | 30 | 1.129 | | 40 | 1.179 |

sgToBrix(sg: number): number

Converts specific gravity to degrees Brix.

| SG | Brix | |-------|------| | 1.000 | 0 | | 1.004 | 1 | | 1.040 | 10 | | 1.083 | 20 | | 1.129 | 30 | | 1.179 | 40.1 |

platoToSG(plato: number): number

Converts degrees Plato to specific gravity. Uses the same sucrose-solution fit as brixToSG.

| Plato | SG | |-------|-------| | 0 | 1.000 | | 12 | 1.048 | | 20 | 1.083 |

sgToPlato(sg: number): number

Converts specific gravity to degrees Plato (ASBC-fit cubic). This is not the same polynomial as sgToBrix, so the two will not always agree.

| SG | Plato | |-------|-------| | 1.000 | 0 | | 1.048 | 11.9 | | 1.083 | 20 |

sgToPoints(sg: number): number / pointsToSG(points: number): number

Gravity points are (SG − 1) × 1000.

| SG | Points | |-------|--------| | 1.000 | 0 | | 1.040 | 40 | | 1.083 | 83 |

Fermentation

abv(og: number, fg: number): number

Standard homebrew estimate: (OG − FG) × 131.25.

| OG | FG | ABV | |-------|-------|-----| | 1.050 | 1.050 | 0 | | 1.050 | 1.010 | 5.3 | | 1.060 | 1.012 | 6.3 |

abvAlternate(og: number, fg: number): number

Hall / Brewer's Friend alternate. Typically a bit higher than abv on bigger beers.

| OG | FG | ABV | |-------|-------|-----| | 1.050 | 1.010 | 5.3 | | 1.060 | 1.012 | 6.5 |

apparentAttenuation(og: number, fg: number): number

(OG − FG) / (OG − 1) × 100. Returns 0 when OG is 1.

| OG | FG | Attenuation | |-------|-------|-------------| | 1.050 | 1.050 | 0 | | 1.050 | 1.010 | 80 |

Hydrometer

correctHydrometerSG(sg: number, sampleTempF: number, calibrationTempF?: number): number

Corrects a hydrometer reading for sample temperature. Temperatures are in °F. Calibration defaults to 60 °F; pass 68 for a 20 °C instrument.

| SG | Sample | Cal | Corrected | |-------|--------|-----|-----------| | 1.050 | 60 °F | 60 | 1.050 | | 1.050 | 68 °F | 68 | 1.050 | | 1.050 | 80 °F | 60 | 1.052 |

Predicted gravity

predictedOG(fermentables, efficiencyPercent, batchGal): number

Points / PPG method. Mash and steep grains use efficiencyPercent; late boil sugars (lateAddition: true) count at 100% efficiency. Divide by post-boil / into-fermentor batchGal.

PPG ≈ extractPercent / 100 × 46 (sucrose) when ppg is omitted. Explicit ppg wins if both are set.

| Mash | Late sugar | Eff | Gal | OG | |------|------------|-----|-----|-------| | — | — | 75 | 5 | 1.000 | | 10 lb × 36 PPG | — | 75 | 5 | 1.054 | | — | 1 lb × 46 PPG | 0 | 5 | 1.009 | | 10 lb × 36 PPG | 1 lb × 46 PPG | 75 | 5 | 1.063 | | 10 lb × 80% extract | — | 75 | 5 | 1.055 |

Related: extractPercentToPPG(extractPercent) and fermentablePoints(amountLb, ppg).

predictedFG(og, attenuationPercent): number

fg_points = og_points × (1 − attenuation%).

| OG | Attn | FG | |-------|------|-------| | 1.050 | 0 | 1.050 | | 1.050 | 80 | 1.010 | | 1.060 | 70 | 1.018 | | 1.080 | 75 | 1.020 |

IBU

Tinseth (1997). preBoilSG is pre-boil specific gravity (Brewfather-like) — not mid-boil or predicted OG. Dry hop contributes 0 IBU.

Form factors are explicit: pellet 1.1, whole 1.0, plug 1.02 (BeerSmith-style), cryo = pellet 1.1 for MVP (Cryo already carries higher AA% on the label). Default form is pellet. Optional hopUtilizationFactor (default 1) is an equipment multiplier.

Whirlpool / hopstand: Tinseth time factor at contact minutes × a linear temp factor (1.0 at 212°F, 0.15 at 170°F, clamp outside that band).

tinsethIBU(hops, preBoilSG, volumeL, hopUtilizationFactor?): number

Mass in grams, volume in liters, alpha acid as a percent (e.g. 6), whirlpool temperature in °F.

| Addition | Pre-boil | L | IBU | |----------|----------|----|-----| | 30 g, 6% AA, 60 min boil, whole | 1.040 | 20 | 22.7 | | same, pellet | 1.040 | 20 | 25 | | 30 g, 6% AA, 20 min whirlpool @ 212 °F, whole | 1.040 | 20 | 13.8 | | same whirlpool @ 170 °F | 1.040 | 20 | 2.1 | | dry hop | 1.040 | 20 | 0 |

Related: tinsethUtilization(preBoilSG, timeMin), whirlpoolTempFactor(tempF), hopFormFactor(form).

Color

maltColorUnits(colorLovibond, amountLb, batchGal): number / moreySRM(mcu): number

MCU = (°L × lb) / gal. Morey: SRM = 1.4922 × MCU^0.6859.

| MCU | SRM | |-----|------| | 0 | 0 | | 1 | 1.5 | | 10 | 7.2 | | 16 | 10 | | 50 | 21.8 |

srmToEBC(srm): number

EBC ≈ SRM × 1.97.

| SRM | EBC | |-----|------| | 7.2 | 14.2 | | 10 | 19.7 |

Volume

Thin numerics only — no vessel deadspace or 3-vessel pipeline. Shrinkage defaults to 4%. Strike temperature is °F. Palmer: strike_F = (0.2 / qt_per_lb) × (target_F − grain_F) + target_F.

| Call | Result | |------|--------| | boilOffGal(1.25, 1) | 1.25 | | applyShrinkage(5) | 4.8 | | undoShrinkage(5) | 5.208 | | grainAbsorptionGal(12, 0.12) | 1.44 | | strikeTemperatureF(152, 70, 1.25) | 165.1 |

Water

Kolbach residual alkalinity, Troester/Braukaiser mash pH (RA + grain acidity from color — not deLange), salt ion yields, lactic acidification, and RO/diluent blend. Ions are Ca, Mg, Na, Cl, SO₄, alkalinity as CaCO₃ (ppm).

Salt hydrates are explicit in the API. Calcium chloride is CaCl₂·2H₂O (anhydrous is not assumed). Yields are ppm Δ per gram per US gallon (Ken Schwartz / Palmer). saltIonDeltaPerGramPerLiter is the SI helper. Lactic strength % is always an argument (default 88). Phosphoric, NaCl, pickling lime, and deLange are out of v1.

Chalk (CaCO₃) Δions are the stoichiometric table values (dissolve-with-CO₂ / mash-acid path), not the half-alkalinity spreadsheet hack.

residualAlkalinity(ions): number

RA = alkalinity − (Ca/3.5 + Mg/7) (ppm as CaCO₃). Ca and Mg are ion ppm.

| Ca | Mg | Alk | RA | |----|----|-----|------| | 0 | 0 | 0 | 0 | | 50 | 10 | 50 | 34.3 | | 100| 20 | 200 | 168.6| | 140| 10 | 20 | -21.4|

saltIonDelta(salt, grams, gallons): WaterIons

| Salt (1 g / 1 gal) | Formula | Δions | |--------------------|---------|-------| | gypsum | CaSO₄·2H₂O | Ca 61.5, SO₄ 147.4 | | calciumChloride | CaCl₂·2H₂O | Ca 72.0, Cl 127.4 | | epsom | MgSO₄·7H₂O | Mg 26.1, SO₄ 103.0 | | bakingSoda | NaHCO₃ | Na 72.3, alk 157.4 | | chalk | CaCO₃ | Ca 105.8, alk 264.2 |

lacticAlkalinityDrop(ml, gallons, strengthPercent?): number

| Call | Result | |------|--------| | lacticAlkalinityDrop(1, 1, 88) | 155.6 | | lacticAlkalinityDrop(2, 5, 88) | 62.2 | | lacticAlkalinityDrop(1, 1, 44) | 77.8 |

Related: applyLactic, lacticAlkalinityDropSI.

troesterMashPH(raPpm, colorSRM, thicknessLPerKg?, roastedFraction?): number

DI mash pH 5.6 plus Braukaiser color shift −(SRM × (0.21·(1−roast) + 0.06·roast)) / 12, then RA × spH where spH = 0.013·R + 0.013. Default thickness 4 L/kg. roastedFraction 0 = all crystal/non-roast.

| Call | Result | |------|--------| | troesterMashPH(0, 2) | 5.57 | | troesterMashPH(0, 10) | 5.43 | | estimatedMashPH({ca: 50, mg: 10, na: 0, cl: 0, so4: 0, alkalinity: 50}, 2) | 5.61 | | troesterMashPH(178, 2) | 5.80 |

Related: estimatedMashPH(ions, colorSRM, …), blendWater(source, fractionTowardDiluent, diluent?) (omitted diluent = RO/DI zeros).

Development

Source lives in src/. Compiled CommonJS and type declarations are emitted to lib/.

npm test        # Jest via ts-jest
npm run build   # tsc → lib/

License

ISC