How strong are Thai mushrooms? What one lab measured

One laboratory study has measured a cultivar labelled Thai: dried Thai Cubensis mushrooms contained on average 0.879% psilocybin plus psilocin by weight, about 8.8 milligrams per gram. That was the lowest of the five cultivars in the study, against 1.36% for the strongest (Goff et al., 2024). The shop that sells the Thai kits describes its potency as similar to Mexican. Neither tells you how strong your own harvest is.

The 2024 study

Researchers at the University of Texas at Arlington developed a method to measure psilocybin and psilocin in Psilocybe cubensis with liquid chromatography and tandem mass spectrometry, and tested it on five cultivars of dried, intact mushrooms. They analysed three whole mushrooms per cultivar individually, so they could see differences between cultivars and between mushrooms of the same cultivar.

A second, independent laboratory tested part of the samples and got comparable results. Two co-authors work for the maker of the instrument used and three for the supplier of the reference standards; the paper declares this.

According to a 2025 review that tabulates the study, the Thai material was grown in a laboratory by the Scottsdale Research Institute in Arizona (Kurzbaum et al., 2025). That matters: it is one culture, from one grower, which may or may not be the same line as a Thai kit sold in the Netherlands.

What the number does and does not tell you

It is one data point. The study was designed to test a measuring method, and three mushrooms from one batch is a small sample for a whole cultivar. The authors reported differences between individual mushrooms of the same cultivar, and the second laboratory got more consistent results when several mushrooms were ground together before testing. Single mushrooms differ.

Lowest of five, yet called relatively strong. The other four cultivars in the study are known as strong ones. The 2025 review lists Thai Cubensis among the cultivars "with relatively high psilocybin content", citing the same study. Both readings come from the same 0.88%: lower than the four others, and high enough for a review to group it with them.

The name does not guarantee the genetics. The same review notes that cultivars sold under the same name often lack genetic similarity across suppliers. A Thai kit from one producer and a Thai culture in a US laboratory share a name; whether they share a lineage is unknown.

Fresh mushrooms are mostly water. The 0.88% applies to dried mushrooms. Per gram of fresh mushroom the content is far lower, because most of the fresh weight is water that is lost in drying.

Converting to amounts

As arithmetic only, using the study average for Thai:

Read the table as an order of magnitude. Your harvest may be well above or below the study average, which is why careful users start low with every new batch. Effects can take up to an hour to begin, according to the Trimbos Institute, and a second portion taken because nothing seems to happen yet comes up again and again in reports of experiences that became too strong. The effects page explains the timeline.

The shop's comparison

Dutch-Smart writes that Thai mushrooms are, in terms of potency, "similar to Mexican magic mushrooms". Mexican was not part of the 2024 study, so this cannot be checked against lab data. It is the shop's assessment of the lines it grows. Its kits of both cultivars are below, with B+ for those who want a cultivar that measured higher in the same study.

A precision scale is the simplest way to turn a harvest into known portions.

Next: the effects as described, or a composite trip report.