Lactic acid calculator
How much lactic acid does your brewing water need? Enter the volume, the water's alkalinity and pH, and your target — the dose comes from exact carbonate equilibrium, the same engine behind brewwtr's sparge acidification.
How it works
The carbonate system's species fractions are computed at your water's pH and at the target, giving the exact acid (in milliequivalents) needed to convert bicarbonate toward carbonic acid — no rules of thumb, no safety fudge factors. That requirement becomes a physical dose using lactic acid's dissociation at the target pH and the measured density of your strength.
FAQ
How much lactic acid per gallon is typical?
For sparge water at moderate alkalinity (around 100 ppm as CaCO₃), expect roughly 0.4–0.6 mL of 88% lactic per gallon to reach pH 5.5. Very alkaline water can need two to three times that.
My lactic acid isn’t 88% — does it matter?
Yes, proportionally. 88% is the common homebrew strength; enter your product’s percentage and the dose scales using the acid’s density curve, not a linear guess.
Will lactic acid affect flavor?
Lactate becomes taste-detectable around 400 ppm in the finished beer — far above what water acidification produces. Typical sparge doses contribute well under 100 ppm.
Can I use this dose for my mash?
No — mash pH depends on the grain bill’s acidity and buffering, not just the water. Use the full calculator, which models the mash and goal-seeks the dose.
Method: carbonate equilibrium with the free-H⁺ term kept exact; lactic dissociation at pKa 3.86; density from published solution data. Validated against hand-computed worked examples in the brewwtr test suite.