Coffee Calculators
Barista Water Recipe Calculator
https://www.coffeesizing.com/calculators/barista-water-recipe/
Estimate only — not a cupping score, a water lab or a roast profile. Confirm on a test brew.
Barista Water Recipe Calculator
GH/KH is the short version of brewing water: general hardness (calcium and magnesium) and carbonate hardness (alkalinity). Specialty recipes often sit near 50–80 ppm GH and ~40 ppm KH as CaCO₃. This page doses Epsom salt for GH and baking soda for KH into a known volume of very soft or distilled water.
Inputs
Results
- Epsom salt
- 197.0mg
- Baking soda
- 67.2mg
- Epsom salt
- 0.197g
- Baking soda
- 0.067g
Recommended gear
Water filter pitcher
If you are not on distilled, strip chlorine and some hardness first. This recipe assumes a near-zero starting water.
Typical range: $20–$50
0.1 g coffee scale
0.1 g is coarse for a 1 L batch of bicarb. Prefer 0.01 g if you can; otherwise concentrate a 10× bottle.
Typical range: $20–$80
Coffee refractometer
Water TDS is not GH, but a sudden jump after mixing means you dumped the concentrate twice. Check, then brew.
Typical range: $80–$400
Calculation method
Epsom salt (MgSO₄·7H₂O) contributes GH: milligrams ≈ target GH ppm × litres × 2.46. Baking soda contributes KH: milligrams ≈ target KH ppm × litres × 1.68. Grams are those milligrams divided by 1000. The factors assume heptahydrate Epsom and sodium bicarbonate into mineral-free water. Calcium chloride recipes need a third salt this page does not dose.
Exact formula
epsomMg ≈ targetGhPpm × volumeL × 2.46. bakingSodaMg ≈ targetKhPpm × volumeL × 1.68. Grams are mg / 1000. Limits: Hydrate form, tap minerals already present, and potassium bicarbonate alternatives omitted; KH from bicarb is not a full SCA ion recipe.
Concentrate bottles
For 0.1 g scales, mix a 10× concentrate in 100 ml and pipette. Errors shrink. Label GH and KH so you do not fortify twice.
Espresso vs filter
Espresso often likes a bit more GH for sweetness; filter can taste sharper at the same KH. Change one target at a time and pull the same coffee.
Frequently asked questions
Can I use tap water as the base?
Only if you know its GH and KH and subtract them. This calculator starts from zero. Adding 40 ppm KH on top of 120 ppm tap KH mutes every espresso.
Why no calcium?
This is the simple magnesium + bicarb pair. Many barista recipes also add CaCl₂. Use it if you want, but not with these two outputs.
Scale in the kettle?
GH still scales boilers. KH drives alkalinity and flavour buffering. Descale on hardness and throughput, not because the recipe ‘is soft’.
More in this topic
All tools in this topicWater chemistry
Coffee Buffer & Acidity Calculator
Compare water KH to brew TDS for a simple buffer index and whether acidity is likely muted. Alkalinity fights acids; it does not erase roast.
Water chemistry
Descaling Frequency Calculator
Estimate days and shots until a descale from water hardness, daily shots and boiler volume. A maintenance schedule, not a plumber.
Water chemistry
Water Bypass Calculator
Add bypass water to a brewed batch to hit a lower target TDS. Beverage mass goes up; extraction yield of the grounds stays where it was.
Water chemistry
Water Hardness & Alkalinity Calculator
Convert GH and KH from ppm as CaCO₃ into German degrees and their ratio. Useful when a test kit and a coffee recipe disagree on units.