How is the lactic acid dose estimated?

The tool models beer as a buffered solution and converts the pH change you want into hydrogen-ion demand, scaled by a buffering capacity factor typical of finished beer. It then converts that demand to millilitres of 88 percent lactic acid using the acid's concentration and molar mass. Because real buffering varies, treat the result as a strong starting estimate.

Why can't pH be lowered exactly by formula alone?

Beer contains proteins, phosphates and organic acids that resist pH change, and this buffering differs between recipes. A formula gives a close estimate, but the only reliable method is to dose in small increments and re-measure with a calibrated meter until you hit the target.

What pH should a finished sour beer be?

Most balanced sour and mixed-fermentation beers sit between pH 3.2 and 3.6. Below about 3.0 the acidity becomes sharp and aggressive; above 3.7 the sourness reads as soft or flat. Gose and Berliner Weisse are often in the 3.2 to 3.4 range.

Why use lactic acid rather than other acids?

Lactic acid gives the soft, clean, slightly creamy sourness associated with Lactobacillus fermentation, which is what most sour-beer styles are built on. Phosphoric acid is flavour-neutral but tastes mineral, and acetic or citric acid push the profile toward vinegar or citrus.

Can I over-acidify and ruin the beer?

Yes. Over-acidified beer tastes harsh and thin, and you cannot easily reverse it without blending in less-sour beer. Always under-dose your first addition, re-measure, and creep up to target. Keeping some unsoured beer on hand lets you correct an overshoot.

What is the Sour Beer Lactic Acid Titration Calculator?

Estimate the millilitres of 88% lactic acid needed to drop a finished beer from its measured pH to a target pH. Built for blenders finishing mixed-fermentation and kettle-sour beers without refermentation, with buffering-aware dosing. It runs free in your browser on Gera Tools, with nothing uploaded.

Sour Beer Lactic Acid Titration Calculator

Name: Sour Beer Lactic Acid Titration Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Blenders and kettle-sour brewers often need to fine-tune the pH of a finished beer without refermenting it. This calculator estimates the lactic acid addition needed to drop the beer from its current measured pH to your target, so you can dial in clean, balanced sourness.

How it works

pH is logarithmic, so each step down represents a tenfold increase in hydrogen-ion concentration. The tool converts the pH change into hydrogen-ion demand:

[H+] demand ∝ 10^(-target pH) - 10^(-current pH)

Because beer resists pH change through buffering, this raw demand is scaled by a buffering capacity factor typical of finished beer. The scaled demand is then converted to millilitres of 88% lactic acid using its concentration (≈ 1.21 g/mL, ≈ 90.08 g/mol):

mL acid = (mol H+ needed) / (mol lactic acid per mL of 88% solution)

The result is reported as a total and as a dose per litre.

Why measure, not just calculate

Real beers differ in protein, phosphate and residual organic acid content, so their buffering varies widely. The formula gives a strong starting estimate, but the only reliable path is to dose in small increments and re-measure with a calibrated pH meter. Under-dose first, then creep up.

Worked example

Suppose you have 20 litres of a mixed-fermentation blonde sitting at pH 3.8 and you want to finish at pH 3.4. The tool calculates the hydrogen-ion demand from that 0.4-unit drop, scales for beer buffering, and converts to millilitres of 88% lactic acid — for example it might output roughly 4 to 8 mL total, or about 0.2 to 0.4 mL per litre. Start with half that dose, stir gently, wait 60 seconds, measure again, and dose the rest in smaller increments. The first-dose estimate saves you from wildly overshooting; the incremental approach guards against the buffering being different from the model.

Choosing the right target pH

The style and your intended carbonation both influence where you want to land:

Style	Typical finished pH range
Berliner Weisse	3.2 to 3.5
Gose	3.2 to 3.4
Kettle sour golden ale	3.3 to 3.6
Mixed-fermentation farmhouse	3.4 to 3.7
Lambic / gueuze	3.2 to 3.5

Below about pH 3.0 the sourness becomes astringent and can suppress yeast health if you plan any further fermentation. Above 3.7 the beer may read as “soft sour” rather than genuinely tart.

Tips

Target pH 3.2 to 3.6 for most balanced sours; lower for gose-style sharpness.
Add acid slowly while stirring and let it equilibrate for a minute before re-reading.
Keep some unsoured beer on hand so you can blend back if you overshoot.
Lactic acid gives the soft, clean sourness of Lactobacillus; other acids shift the profile toward vinegar or citrus.
Calibrate your pH meter before every session — a drifted probe gives readings that are off by 0.2 to 0.3 units, turning a calculation into guesswork.

All calculations run locally in your browser.