Eighteen published numbers for the psychedelic drugs market. One shows its method on a free page.

On 11 September 2026 one reader spent a day looking for published market-size figures and found eighteen publishers carrying one. Eight of those price psilocybin on its own. The other ten size the wider psychedelics category, and six of those give psilocybin a share or a growth rate inside it while none gives it a dollar value. That is a floor on what is published. It is not a census of it.

Six of the eight land between US$1.80 billion and US$4.32 billion, which looks like agreement and is not. Those six carry six different years, six differently worded objects, and not one of them says what it counted. Nothing here establishes that any two of these count the same thing.

The other two are further apart than the rest of the table is wide. IndustryARC’s page puts psilocybin at US$62.00 million by 2031 and states no method on the page a reader can open. Verified Market Reports puts psychedelic mushrooms at US$64.79 billion in 2024 and states no method on its free page either. Different years, different stated objects, and no way to tell which of them is closer to anything.

There is a reason to be careful with the IndustryARC page beyond its number. Beneath that headline, where the report’s segmentation should sit, the page lists its product types as gallium nitride, gallium arsenide, high-purity gallium, gallium oxide and gallium phosphide, and grades them by gallium purity. That is almost certainly a template error on a press-release page. It is evidence about what a reader relying on free vendor pages is actually looking at. It says nothing about the report itself.

Of the eighteen, one states a counting method on its free page. Two publish a list of source types with no base and no assumptions. The remaining fifteen say nothing on their free pages about how the figure was arrived at.

All but one of these is sold, and the free page is an advertisement for it. A methodology section may well sit inside the paid document; what is established is what a reader can check for free, which is the position every reader of these figures is in.

The one that does state a method is one of the ten, and it gives psilocybin no dollar value of its own. Market Research Future says its estimates

A disclosed method is not a validated one. Nothing here checks whether that modelling was done well, or at all; it is the publisher’s own account of its own work, and it cannot be verified from outside the paid report. It also inherits whatever its inputs are worth.

Esketamine is an approved antidepressant derived from ketamine, and it is not psilocybin. A figure built bottom-up from esketamine prescriptions is measuring something real, and a reader who quotes it as the size of the psychedelics market is quoting a number whose largest stated input is a different drug with a different regulatory history. That is disclosed on the page, by the publisher, for anyone who reads down that far.

The one firm that shows its working builds partly on licensed-centre throughput from Oregon and Colorado, which are the two American states that publish anything at all about this. What they publish is not identical to what the method claims to use: Colorado publishes a licence register, and a licence is not a throughput.

Five things have been counted, every one of them by a government or a funder.

Public money. An obligation is recorded when it is promised and not when it is spent, so a concentration in recent years is partly a fact about how the register records things. With that in front: NIH RePORTER states US$90,053,627 of extramural obligations across the 133 of 150 project-year records under the narrow predicate that carry an amount, from FY2016 to FY2026, on a read of 7 September 2026. US$66,709,633 of that falls in FY2025 and FY2026 together, three quarters of everything the register states under the narrow predicate, to date, the federal year not having ended when it was read. Two other national funders publish their own: on the same read, CIHR states CAD 15,467,148 over 50 award records and UKRI GBP 2,195,745 across six. Three currencies, three clocks, and no way to add them.

Service volume. Oregon reports 5,935 clients served in calendar 2025, and 2,172 in the first half of 2026, a half-year figure this work has not tested for seasonality or for any change in reporting basis and which therefore does not annualise. That is a count of clients served in a period and never a count of people, and it is a fact about a regulated state programme.

Licences. Colorado’s Natural Medicine Division register carried 44 healing-centre licences at status Approved, held by 43 organizations, on the 5 September 2026 read, and 103 licences of every class: 72 Approved, 15 Pending, 9 Withdrawn, 4 Voluntary Surrender and 3 Denied. Approved is the register’s word for an authorisation. It does not mean a centre is open, or has served anyone.

A state-regulated service programme is not a prescription, a medicine or a medical treatment.

Permissions to treat. Switzerland’s annual figures here are stocks and not flows, because a Swiss authorisation counts a continuing patient again each year, so the difference between two of them is not a number of new patients. On that basis: Switzerland issued 322 exemption authorisations in 2024, up from 43 in 2021. Australia reported 47 new patients through 30 June 2025, none of them in the first six months, and those are new patients drawn from returns prescribers choose to file. Separately, and over a different period ending 28 November 2025, 36 of 40 prescriber applications were approved. The two do not divide into one another: they cover different windows, and an approval permits a prescriber to act while counting nobody. Canada had authorised psilocybin for 50 patients through its Special Access Program as of 4 November 2022, which is the department’s own figure and its most recent published one.

Kilograms. Governments reported 19.22 kilograms of psilocybine manufactured worldwide in 2024, against 36.10 in 2023. That is the pure-substance layer reported under the 1971 Convention, and it excludes every mushroom grown under an American state programme.

An authorisation is a permission. A client visit is a service. An obligation is a promise to pay over years. A kilogram is a kilogram. Five counts, five units, five clocks, and nothing in that list is a revenue figure.

Of everything counted above, exactly one thing is shaped like revenue: Oregon’s 15 percent retail tax on psilocybin products under ORS 475A. It is a rate on product sales, and this work did not read the sales. Oregon publishes product and sales data of its own, and at least one tracker has derived a revenue figure from it; neither is counted here, and neither is what the eighteen reports are measuring. Nothing else on this page stands in for that base, and in particular the client count above is a count of services and not of product revenue.

The registers produce counts that are narrow, dated and checkable, and that refuse to add up. The reports produce a single number that adds up beautifully and, on the page a reader can open, seventeen times out of eighteen declines to say how it was counted.

Who is permitted to make the drug is a separate question with its own answer, and so is who pays for the research and who owns the companies. Neither of those produces a market figure either.