Water chemistry calculator

Free water chemistry calculator — live gypsum & CaCl₂ for mash & sparge

Free water chemistry calculator: enter your source water, pick a style, get live gypsum & CaCl₂ doses for mash and sparge — no signup.

Your source water
💡 Find these on your water utility's website (drinking water analysis) or in your lab report.
Water volumes
Total: 35.0 L. Salts are split proportionally between mash and sparge water.
Target profile
Hop-forward: High sulfate enhances bitterness & dryness
Examples: IPA, Pale Ale, NEIPA, Double IPA
Target mash pH: 5.2
Target values from the style — switch to »Manual« to edit
Ca²⁺
100 ppm
Mg²⁺
10 ppm
Na⁺
10 ppm
Cl⁻
50 ppm
SO₄²⁻
200 ppm
HCO₃⁻
25 ppm
57
Water match
Adjustment needed
Difficult ions (excess in source water):
HCO₃⁻+95 ppm (blending recommended)
Tip: Without blending with RO water, this style can't be matched perfectly with your water. Salts alone can't reduce minerals.
Recommended additions
Gypsum (CaSO4)
10 g
Raises sulfate by ~160 ppm for bitterness and crispness.
Mash
5.7 g
Sparge
4.3 g
Calcium Chloride (CaCl2)
1.5 g
Raises chloride by ~20 ppm for malt character and body.
Mash
0.9 g
Sparge
0.6 g
Lactic Acid 80%
11 ml
pH reduction to ~5.2
Mash
6.3 ml
Sparge
4.7 ml
Source vs. target
Ion
Source
Target
Ca²⁺
50
100
Mg²⁺
10
10
Na⁺
10
10
Cl⁻
30
50
SO₄²⁻
40
200
HCO₃⁻
120
25

Turn this water into a complete recipe

Your water profile carries over — the AI builds a matching recipe. Then save it to your free account: with shopping list & step-by-step brew day.

How the brewing water calculator works

Water is the largest ingredient in every beer — and the most underrated. The minerals in brewing water (calcium, magnesium, sodium, chloride, sulfate, bicarbonate) determine mash pH, hop perception, and the mouthfeel character of a style. Want a mash pH estimate from grain bill and water? Use the dedicated mash pH calculator for grain + lactic acid guidance.

The calculator compares your source water to the optimal profile for the chosen style and recommends specific salt additions. Gypsum (CaSO₄) adds sulfate for bitterness and dryness, calcium chloride adds chloride for fullness and sweetness, epsom salt raises magnesium, and 80% lactic acid lowers alkalinity.

Important: salts can only be added, never removed. If your water is significantly above target on any ion (e.g. HCO₃⁻), only blending with reverse osmosis water or acid correction will get you there. That's exactly what our match score shows: a value below 40 means salts alone won't hit the target.

Find more brew-day tools in our overview of all brewing calculators — IBU, ABV, carbonation, yeast starter and more.

Frequently asked questions

Where do I find values for my tap water?▼
Most water utilities publish an annual drinking water analysis online. Search for 'drinking water report [your municipality]'. You need Ca, Mg, Na, Cl, SO₄ and HCO₃ in mg/L (= ppm). If only hardness is given: 1 °dH ≈ 7.14 ppm CaCO₃, that's a rough estimate. More accurate is a water test through a brewing lab (~$30-50) or a homebrewer water test kit.
How is this different from the mash pH calculator?▼
This page targets ion targets and brewing salt dosing for mash and sparge after you pick a style. The separate mash pH calculator estimates pH from the grain bill and water and suggests aciduated malt or lactic acid. Use both together on brew day.
What does preparing brewing water mean?▼
Preparing brewing water means pushing calcium, chloride or sulfate upward with salts, or lowering excess hardness or alkalinity with RO dilution or lactic acid up to taste limits. Salts alone never remove ions. This calculator prints grams per batch for gypsum and related additions for your volumes.
Which water profiles work for different beer styles?▼
Rule of thumb: pale lagers (Pilsner, Helles, Kölsch) need very soft water with low minerals. IPAs benefit from high sulfate (200+ ppm) for dry bitterness. Stouts and porters tolerate high alkalinity (HCO₃ 150-200) because of roasted malt acidity. Belgian ales and witbier want balanced sulfate:chloride ratios. The calculator applies these profiles automatically when you pick the style.
What is the sulfate-to-chloride ratio (SO₄:Cl)?▼
The ratio of sulfate to chloride determines the character of the beer. Above 2:1 → dry, hoppy (typical IPA). Around 1:1 → balanced (typical Pale Ale). Below 1:2 → malty, full-bodied (typical Stout, Bock). Both ions are present in traces in nearly every water, but the ratio makes the flavor difference.
What if my water is too hard?▼
Hard water (high HCO₃, Ca, SO₄) can only be reduced by diluting with reverse osmosis water (RO). Salts can only add, not remove. A 50:50 RO blend halves all ions, then the calculator can salt up precisely. For alkalinity (HCO₃), 80% lactic acid works too, but only up to the taste threshold (~0.5 ml/L) — the calculator warns automatically if this is exceeded.
Salts in mash only or sparge too?▼
Salts go into both volumes because they affect the entire wort. The calculator splits the total amount proportionally to water volume. Acids (lactic, phosphoric) are most important in the mash for pH, the sparge often needs only a smaller stabilization dose. If you want to be precise: 70-80% of acid in the mash.

Use these values in a recipe

IBU, CO₂, batch size or water profile carry into the wizard — pick a style and generate.

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