Low, but not zero
Kombucha is a fermented tea drink. The USDA FoodData Central entry for kombucha lists 11 mg of caffeine per 100 g, which works out to about 41 mg in a 12 oz serving. The caffeine comes from the black or green tea used as the base; fermentation reduces it only slightly.
The actual number varies by brand and recipe. Kombucha brewed from black tea tends to be higher than one brewed from green tea. Longer fermentation may reduce caffeine a little further because some microbes can metabolise it, but the effect is small and inconsistent.
Kombucha as a low-caffeine option
At roughly 40 mg per 12 oz, kombucha is one of the lowest-caffeine options on the site. It is comparable to an 8 oz green tea or a small black tea and far below a typical coffee or energy drink.
Because the dose is low, kombucha is unlikely to disrupt sleep for most people when consumed in moderation. However, the acidic nature of the drink can aggravate reflux in some individuals, so tolerance to the beverage itself is separate from tolerance to the caffeine.
What the label may not tell you
Kombucha brands rarely list caffeine on the front label. Some list it on the nutrition facts, but many do not because the amount is below the threshold that requires disclosure in some jurisdictions. If you are sensitive to caffeine or tracking your daily total, look for the tea base listed in the ingredients. Black-tea-based kombuchas are higher in caffeine than green-tea-based ones, and some flavoured commercial versions add extra tea extract.
Source
The caffeine figure is from USDA FoodData Central, tea, kombucha, checked 19 September 2026.