Sulfate-to-chloride ratio: crisp and bitter or soft and malty

SO₄:Cl ratios by style, the ppm each gram of gypsum or calcium chloride adds, with worked 20 L examples for a West Coast IPA and a NEIPA.

24 Sept 2026 · 6 min read

Sulfate (SO₄²⁻) and chloride (Cl⁻) don't add bitterness or sweetness themselves, but they change how we perceive them: sulfate makes hop bitterness sharper and drier with a clean finish; chloride makes the body rounder and the malt fuller. Their ratio is the simplest dial for tuning a recipe's balance.

Ratio by style

SO₄ : Cl	Perception	Styles
≤ 0,5 : 1	Rất đằm malt, thân dày · Very malty, full	NEIPA, Milk Stout
0,75–1 : 1	Ưu tiên malt · Malty	Stout, Porter, Amber Ale
1–1,5 : 1	Cân bằng · Balanced	Pale Ale, Blonde Ale, bia lúa mì · Wheat beer
2–3 : 1 (hoặc cao hơn)	Đắng giòn, khô · Bitter, dry	West Coast IPA, American Pale Ale

A ratio only matters at meaningful levels: 10 ppm : 5 ppm is also 2:1 but barely noticeable. Aim for at least ~40–50 ppm of each ion, and keep sulfate below ~350 ppm to avoid a harsh mineral bite.

What one gram of salt adds

Salt (1 g in 10 L)	Ca²⁺	SO₄²⁻	Cl⁻
Thạch cao · Gypsum CaSO₄·2H₂O	23,3 ppm	55,8 ppm	—
Canxi clorua ngậm nước · CaCl₂·2H₂O	27,3 ppm	—	48,2 ppm
Canxi clorua khan · CaCl₂ (anhydrous)	36,1 ppm	—	63,9 ppm

For other volumes: ppm = grams × table factor × 10 ÷ litres of water. Granular calcium chloride is usually the dihydrate; the anhydrous form is strongly hygroscopic, so weigh it quickly and keep it sealed.

Worked examples for 20 L of RO water

Target	Salts	Result
West Coast IPA	3 g gypsum + 1 g CaCl₂·2H₂O	Ca 49 · SO₄ 84 · Cl 24 ppm → ≈ 3,5 : 1
NEIPA	1 g gypsum + 2,5 g CaCl₂·2H₂O	Ca 46 · SO₄ 28 · Cl 60 ppm → ≈ 0,5 : 1
Pale Ale cân bằng · balanced	2 g gypsum + 2 g CaCl₂·2H₂O	Ca 51 · SO₄ 56 · Cl 48 ppm → ≈ 1,2 : 1

If you brew with tap water instead of RO, add the ions already in it (see the article on reading a water report). Weigh salts on a 0.1 g scale — a 1 g error in a 20 L batch shifts things by almost 30 ppm.