Tools
Calculators
Two things worth recomputing rather than remembering: what fraction of the coffee ended up in the cup, and what a weighed salt recipe actually produces once diluted. Both are shown with their working, and neither asserts a target.
Extraction yield
What proportion of the dry coffee ended up dissolved in the cup. It needs a refractometer reading; without one, the brew ratio is the only part of this you can know.
Mass, not volume.
From a refractometer, as a percentage.
- Brew ratio
- 1 : 2.00Beverage mass divided by dose.
- Dissolved solids
- 3.42g
- Extraction yield
- 19.00%Beverage mass × TDS ÷ dose.
No target is given here on purpose. The commonly quoted 18–22 per cent band is a convention whose provenance this publication has not yet established, and quoting it as though it were a specification is the habit the site exists to check.
Water from a salt concentrate
Enter the salt masses you weighed into a concentrate, then the dilution. The tool converts those masses into carbonate-equivalent hardness and alkalinity. It does not recommend a recipe, establish potability, ingredient purity, taste suitability, or machine-warranty compatibility.
MgSO₄·7H₂O. Supplies magnesium.
NaHCO₃. Supplies alkalinity.
CaCl₂·2H₂O dihydrate. Supplies calcium.
Total parts of finished water.
- Magnesium hardness
- —As CaCO₃.
- Calcium hardness
- —As CaCO₃.
- Total hardness
- —As CaCO₃.
- Alkalinity
- —As CaCO₃.
Carbonate-equivalent chemistry only. Do not treat the outputs as drinking-water guidance or as clearance for any espresso machine’s warranty terms.
How the conversion works
Grams of salt are divided by molar mass to give moles, spread over the concentrate volume, then divided by the dilution. Molar masses used: magnesium sulphate heptahydrate 246.466, sodium bicarbonate 84.006, calcium chloride dihydrate 147.008, calcium carbonate 100.086 g/mol.
Hardness is reported as calcium carbonate equivalent, so one millimole of a divalent cation counts as 100.086 mg/l. Alkalinity is also reported as calcium carbonate, but bicarbonate carries one equivalent per mole against carbonate’s two, so one millimole counts as 50.043 mg/l. This is why the same weight of bicarbonate and of Epsom salt do not produce comparable numbers.
Sulphate, chloride and sodium are supplied along with the cations and are not converted here, because they are not expressed as carbonate equivalents.