How much psilocybin is in Psilocybe cubensis? What labs measured

Two studies, nineteen strains

Only two peer-reviewed studies we found measured several named cubensis strains with one method. They used different instruments, different drying and different sources of mushrooms, so their numbers are best read within each study, not across.

Study 1. A chemistry group at the University of Texas at Arlington developed a liquid chromatography and tandem mass spectrometry method and measured three whole dried mushrooms per strain. A second laboratory measured part of the material and found comparable results (Goff et al., 2024). Two of the co-authors work for the maker of the instrument and three for the supplier of the reference standards, which the paper declares.

Study 2. A group at Tel-Hai College and the University of Haifa in Israel grew 14 strains under the same conditions: coco and vermiculite substrate, 25 °C, a 12-hour light cycle and humidity above 80 percent. The mushrooms were freeze-dried, ground and analysed by liquid chromatography with a photodiode array detector. DNA barcoding confirmed that all 14 were P. cubensis (Sharchaton et al., 2026). The cultures came from two suppliers, one in Israel and one in Texas.

"All tryptamines" adds the related compounds baeocystin, norbaeocystin and aeruginascin, which were present in small amounts in some strains. Total tryptamines differed 7.8-fold between the highest and lowest strain.

Two details stand out. Jack Frost, which grower descriptions call highly potent according to the 2025 review (Kurzbaum et al., 2025), was among the lowest in this study. And Golden Teacher, one of the most searched strain names, was only measured as one half of a cross.

One strain, many mushrooms

The Israeli study also measured single fruit bodies separately for six strains. The coefficient of variation for psilocybin was 12.8 to 23.4 percent: mushrooms of the same strain, grown in the same chamber and harvested together, still differed noticeably. The Texas group saw the same effect from the other side: their results became more precise when several mushrooms were ground together before analysis.

One culture, several harvests

A culture produces mushrooms in successive flushes. A 1982 study followed P. cubensis in controlled culture through repeated harvests. Psilocybin, nearly always at least twice the level of psilocin, showed no upward or downward trend but varied by a factor of four. Psilocin was usually absent in the first flush, sometimes also in the second, and peaked by the fourth. Samples from outside sources varied by more than a factor of ten (Bigwood and Beug, 1982).

Cap, stem, mycelium and spores

A study from the University of Chemistry and Technology in Prague measured the parts separately (Gotvaldová et al., 2021):

The difference between caps and stems was not statistically significant, because single fruit bodies varied so much. The absence of tryptamines in spores matters legally: in the United States, spores that contain no psilocybin or psilocin are not controlled under federal law; see legal status.

Storage changes the numbers

The same Prague study tested storage. Tryptamines broke down fastest in fresh mushrooms kept at minus 80 °C and slowest in dried material kept in the dark at room temperature. A laboratory figure describes the sample on the day it was measured; how it was dried and stored before that matters as much as its strain.

Reading strain potency claims

• A potency claim without a laboratory, a method and a sample size is a description, not a measurement.
• Results from different studies use different units and methods. Percent of dry weight times ten gives milligrams per gram.
• Most of the strain names in the strain index have no published measurement at all.
• Even where a strain has been measured, its next harvest, its next mushroom and the same name from another supplier may differ.

Why the same name can stand for different cultures is explained on strain names.