# Home Brewing Water Chemistry Calculator Turn source water, RO dilution and salt additions into a full ion profile, sulfate-chloride ratio and residual alkalinity. --- - **Canonical URL:** https://dothecalculation.com/calculators/home-brewing-water-chemistry-calculator - **Category:** Hobbies & Leisure Utilities - **Publisher:** Do The Calculation (https://dothecalculation.com) - **Cost:** Free, no account or sign-up required - **Privacy:** Runs entirely in the browser; inputs are never sent to a server - **Methodology:** https://dothecalculation.com/methodology --- ## Build a Brewing Water Profile From Salt Additions Source water, RO dilution and salt additions in grams, converted into a full ion profile with the sulfate-to-chloride ratio and residual alkalinity that actually decide the beer. - Ion contributions derived from molar mass, not copied from a chart - Sulfate-to-chloride ratio with a plain-language read on the balance - Kolbach residual alkalinity, so the grist and the water can be matched ## Quick Answer — How Brewing Salts Change Your Water Each brewing salt contributes ions in proportion to its formula weight. One gram of a salt dissolved in one litre of water contributes, in parts per million, the ion's share of the salt's molar mass multiplied by 1,000. Those figures are fixed chemistry, not a matter of opinion: • **Gypsum** (CaSO₄·2H₂O) — 232.8 ppm calcium, 558.0 ppm sulfate per g/L • **Calcium chloride** (CaCl₂·2H₂O) — 272.6 ppm calcium, 482.3 ppm chloride • **Epsom salt** (MgSO₄·7H₂O) — 98.6 ppm magnesium, 389.7 ppm sulfate • **Table salt** (NaCl) — 393.4 ppm sodium, 606.6 ppm chloride • **Baking soda** (NaHCO₃) — 273.7 ppm sodium, 726.3 ppm bicarbonate • **Chalk** (CaCO₃) — 400.4 ppm calcium, 1,219.2 ppm bicarbonate Two numbers matter more than the individual ions. The **sulfate-to-chloride ratio** sets how the finish reads: below about 0.8 the beer reads soft and malty, 0.8 to 1.5 is balanced, and above 1.5 the bitterness is accentuated and the finish turns dry. And **residual alkalinity** decides whether the mash pH lands where the grist wants it. ## How to Use This Calculator: A West Coast IPA Enter your source water report, the percentage you are cutting with reverse osmosis or distilled water, and the salt additions in grams for the full batch volume. Take a **30-litre** batch built on moderately soft tap water — **22 ppm calcium, 6 magnesium, 14 sodium, 28 sulfate, 20 chloride, 65 bicarbonate** — cut **50% with RO**, then treated with **8 g gypsum** and **2 g calcium chloride**. The dilution halves every source ion first: calcium falls to 11, sulfate to 14, chloride to 10, bicarbonate to 32.5. Then the salts add **80.3 ppm calcium**, **148.8 ppm sulfate** and **32.2 ppm chloride** across 30 litres. The finished profile is **91.3 calcium, 3.0 magnesium, 7.0 sodium, 162.8 sulfate, 42.2 chloride, 32.5 bicarbonate**. The sulfate-to-chloride ratio is **3.86 to 1** — firmly **hop-forward, dry and accentuated**, which is exactly the West Coast character. Calcium at 91 ppm sits comfortably inside the 50 to 150 range brewers target, and sulfate at 163 is assertive without approaching the 350 ppm point where it starts tasting harsh and mineral. Residual alkalinity comes out at **0.1**, essentially neutral, which suits a pale grist that has little acidity of its own to fight. Once the water is set, the [homebrew ABV and priming calculator](/calculators/homebrew-abv-priming-calculator) handles the other end of the same brew day. ## A Second Example: A Hazy IPA and a Stout, Both From RO Building from **100% RO water** is the cleanest approach because there is nothing to subtract — you are constructing the profile rather than correcting one. For a **23-litre** hazy IPA, **1.5 g gypsum** and **5.5 g calcium chloride** produce **80.4 calcium, 36.4 sulfate, 115.3 chloride** and a sulfate-to-chloride ratio of **0.32** — **malt-forward, soft and rounded**, which is the mouthfeel a hazy is built around. Residual alkalinity is **−23.0**, appropriately low for a pale grist, and calcium sits in range at 80 ppm. The identical batch size for a stout takes a different shape: **2 g gypsum, 2 g calcium chloride and 4 g baking soda** give **43.9 calcium, 47.6 sodium, 48.5 sulfate, 41.9 chloride, 126.3 bicarbonate**. The ratio is **1.16 — balanced** — but the important number is the **residual alkalinity of 91.0**, which is **high and suits brown and porter grists**. That alkalinity is deliberate: dark roasted malts are strongly acidic, and without carbonate to push against them the mash pH drops too far and the beer turns thin and sour rather than round. Note the calcium in that stout is 43.9 ppm, just below the usual 50 ppm floor. That is a real trade-off rather than an error — adding more calcium would drag the residual alkalinity back down, which is the opposite of what the grist needs. Brewing water is a system of competing targets, not a checklist, and the calculator shows all of them at once so the trade-off is visible rather than hidden. ## Reading the Numbers That Matter **Calcium (50 to 150 ppm)** is the workhorse. It supports enzyme activity in the mash, helps yeast flocculate, aids protein coagulation in the boil, and drops mash pH by reacting with malt phosphates. Below 50 ppm the mash and the fermentation both suffer; above 150 there is no further benefit and the water starts tasting mineral. **Sulfate and chloride** are the flavour pair. Sulfate accentuates hop bitterness and dries the finish; chloride enhances malt sweetness and fullness. It is the ratio between them, not the absolute levels, that shapes perception — though sulfate above about 350 ppm turns harsh and chloride above roughly 200 ppm can read as flabby. **Sodium (under about 150 ppm)** rounds and sweetens in small amounts and tastes salty above that. It usually arrives as a by-product of baking soda rather than as a deliberate addition. **Residual alkalinity** is the Kolbach figure: alkalinity as calcium carbonate minus calcium over 3.5 minus magnesium over 7. It measures how much the water resists the acidity of the malt. Pale grists want it near or below zero; dark roasted grists want it high, because they bring their own acid. Getting this wrong is the single most common water mistake, and it shows up as a mash pH outside the 5.2 to 5.6 range where conversion and flavour both work best. One warning: **chalk barely dissolves in water**. The figures here assume full dissolution, which does not happen in a mash without dissolved CO2 to help it. Most brewers use pickling lime or baking soda instead when alkalinity is genuinely needed. Treat any result relying on chalk as an upper bound on what you will actually get. ## Limitations This calculates the ion profile of the finished water. It does not predict mash pH, and the two are not the same thing. Mash pH depends on the grist — how much of it is base malt, crystal, roasted or acidulated — as much as on the water, and predicting it requires a full mash model with malt buffering data. Residual alkalinity tells you which direction the water pushes; only a pH meter tells you where the mash actually landed. Chalk is modelled at 100% dissolution and will not achieve that in practice. Pickling lime and baking soda are the practical alternatives when alkalinity is needed, and both are handled here. The salt additions are applied to the whole batch volume as a single figure. Many brewers split additions between the mash and the sparge, or treat only the mash water, and the effective concentration in each is then different from the batch-average figure shown. If you are splitting, run the mash volume and the sparge volume as separate calculations. Finally, a water report is a snapshot. Municipal supplies vary seasonally, sometimes substantially, and utilities blend sources through the year. If your source water is entering a recipe you care about, either request a recent report, test it yourself, or do what most brewers eventually do and build from reverse osmosis, where the starting point is zero and nothing changes between batches. That predictability is worth more than the specific profile. ## Related Calculators The [Homebrew ABV & Priming Sugar Calculator](/calculators/homebrew-abv-priming-calculator) covers the other end of the same brew day, from original and final gravity through to the priming sugar for a target carbonation. The [Coffee-to-Water Brew Ratio Calculator](/calculators/coffee-brew-ratio-calculator) applies a similar ratio-driven approach to the other drink where water chemistry quietly decides the result. And the [Baker's Percentage Calculator](/calculators/bakers-percentage-calculator) uses the same proportional thinking for the other craft where a few grams either way changes the result. ## Frequently asked questions ### What does gypsum do in brewing water? It adds calcium and sulfate — 232.8 ppm and 558.0 ppm respectively per gram per litre. Calcium supports mash enzymes and yeast flocculation; sulfate accentuates hop bitterness and dries the finish. It is the standard addition for pale, hoppy beers. ### What is a good sulfate to chloride ratio? It depends on the beer. Below about 0.8 reads soft and malty, 0.8 to 1.5 is balanced, and above 1.5 accentuates bitterness. A West Coast IPA at 3.86 is firmly hop-forward; a hazy at 0.32 is deliberately soft and rounded. ### How much calcium should brewing water have? Between 50 and 150 ppm for most beers. Below 50 the mash enzymes, protein coagulation and yeast flocculation all suffer; above 150 there is no further benefit and the water begins to taste mineral. ### What is residual alkalinity? The Kolbach figure: alkalinity as calcium carbonate, minus calcium divided by 3.5, minus magnesium divided by 7. It measures how strongly the water resists the acidity of the malt. Pale grists want it near or below zero; dark roasted grists want it high, because they bring their own acid. ### Should I build my brewing water from RO? It is the most predictable approach, because the starting point is zero and nothing varies between batches. Municipal water changes seasonally as utilities blend sources, and that variability is usually a bigger problem than any particular profile. Building from RO removes it entirely. ### Why does chalk not work well? Because calcium carbonate barely dissolves in water without dissolved CO2 to help it. This calculator assumes full dissolution, which will not happen in a mash, so treat any chalk-based result as an upper bound. Pickling lime or baking soda are the practical alternatives when alkalinity is genuinely needed. ### Does this predict my mash pH? No, and the two are different questions. Mash pH depends on the grist composition — base malt, crystal, roasted, acidulated — as much as on the water. Residual alkalinity tells you which direction the water pushes; a pH meter tells you where the mash actually landed. ### Should I add salts to the mash or the whole batch? Either works, but the concentrations differ. This calculator applies additions across the batch volume you enter, so if you are treating mash and sparge water separately, run each volume as its own calculation rather than splitting the batch figure by eye. ## Related concepts - **Sulfate-to-Chloride Ratio** — The balance between the two flavour ions. Sulfate accentuates hop bitterness and dries the finish; chloride enhances malt fullness. The ratio between them shapes perception more than either level alone. - **Residual Alkalinity** — Kolbach's measure of how strongly water resists the acidity of malt: alkalinity as CaCO3 minus calcium over 3.5 minus magnesium over 7. It is what matches a water profile to a grist. - **Brewing Salts** — Gypsum, calcium chloride, Epsom salt, table salt, baking soda and chalk. Each contributes fixed proportions of specific ions determined by its formula weight, which is why the additions can be calculated rather than guessed. ## Related guides - [How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide](https://dothecalculation.com/blog/site-guides/how-to-use-calculators) — Learn the fastest reliable workflow for using Do The Calculation calculators, reading results, checking formulas, and using save, print, share, and export actions correctly. - [Understanding Calculator Formulas: How DTC Turns Inputs into Results](https://dothecalculation.com/blog/site-guides/understanding-calculator-formulas) — Understand how Do The Calculation formulas are presented, what the explanation blocks mean, and how to verify calculator logic before using a result in a real decision. ## Related calculators - [Quilting Fabric Calculator](https://dothecalculation.com/calculators/quilting-fabric-calculator) — Backing, binding and batting yardage for a quilt, comparing both backing seam orientations to find the cheaper one. - [Binary, Hexadecimal, & ASCII Multi-Base Converter](https://dothecalculation.com/calculators/binary-hex-ascii-calculator) — Convert integers and strings between binary, hexadecimal, ASCII, and decimal formats instantly with this free online conversion tool. - [Blood Donation Eligibility & Regeneration Tracker](https://dothecalculation.com/calculators/blood-donation-interval-calculator) — Track blood donation eligibility dates, countdowns, and iron and plasma regeneration phases instantly with this free tracker tool. - [Estate & Gift Tax Calculator](https://dothecalculation.com/calculators/estate-tax-planning-calculator) — Estimate federal and state estate and gift tax liabilities, applicable exemptions, and net inheritance passed on to heirs. - [Solar Noon, Sunset, & Daylight Duration Calculator](https://dothecalculation.com/calculators/solar-noon-daylight-calculator) — Calculate NOAA solar noon, sunrise, sunset, and total daylight duration based on latitude and longitude coordinates instantly. - [Word Counter Calculator](https://dothecalculation.com/calculators/word-counter-calculator) — Count words, characters, sentences, and paragraphs in real-time, estimate reading times, and analyze word density/readability. --- _Every ppm figure on this page was produced by running this calculator with the stated inputs rather than estimated, and the ion contributions are derived from molar masses rather than copied from a chart. The calculator gives the ion profile of the finished water; it does not predict mash pH, which depends on grist composition as much as on water and needs a full mash model plus a pH meter to confirm. Chalk is modelled at full dissolution and will not achieve that in practice. Salt additions are applied across the batch volume entered, so mash and sparge water treated separately should be run as separate calculations._ --- _Source: [Do The Calculation](https://dothecalculation.com/calculators/home-brewing-water-chemistry-calculator). Quote freely with attribution and a link to this page._