Magic mushroom dosage calculator: what the number can't tell you
Every magic mushroom dosage calculator multiplies your inputs by a potency it has to assume. Lab tests of 14 strains grown the same way found a 9.7-fold spread in psilocybin, so no calculator can know what is in yours.
Your dose, calculated6 unknowns
Missing input: what's in your mushrooms
The short answer
A calculator can only do arithmetic. It can't measure your mushrooms, check your medicines or read your state of mind. Of 36 online calculators we checked on October 26, 2026, 23 require your body weight, although trials found weight didn't predict how strong the effects were, and only 8 name lithium, a medicine linked to seizures when taken with psychedelics.135
If you want a number anyway, the magic mushroom dosage calculator run by the team behind this site at least shows its formula and says which strain's potency it assumes. Read the rest of this page first: the six keys on the calculator are the six things every tool has to guess.
The six things no calculator can know
Each key on the calculator opens one of these. The figures come from published studies; the links lead to the full evidence.
Potency: what's actually in the mushroom
When researchers grew 14 Psilocybe cubensis strains in the same conditions and tested them the same way, psilocybin ranged from 0.20% to 1.96% of dry weight, a 9.66-fold spread. Within each of six strains, five mushrooms from the same growing chamber still varied, with coefficients of variation from 12.8% to 23.4%.2 Wild collections of one species have varied by more than sevenfold.10
Strain: a name, not a measurement
Strain names are trade names. The same study notes there is no genetic reference database for them, and a 2023 study of 86 commercial cubensis cultivars found low genetic diversity across them.29 A calculator's strain menu multiplies by a guess about a name.
Body weight: the input with the least evidence
A pooled analysis of 288 trial participants weighing 49 to 113 kg found no evidence that body weight affected the subjective effects, and a separate study found body mass index didn't predict them either.34 Yet 23 of the 36 calculators we checked require your weight.1
Tolerance: measured in 1961, barely since
The main human study tolerance tools cite is from 1961: 19 volunteers developed tolerance to psilocybin and two-way cross-tolerance with LSD. Its abstract reports no recovery time.6 The tools we checked assume half-lives of about 2.3 to 3 days or reset windows from 5 days to about 4 weeks.1
Medicines: the risk most calculators skip
In 62 online reports of lithium taken with a classic psychedelic such as LSD or psilocybin, 47% described seizures and 39% involved medical attention.5 SSRI and SNRI antidepressants often blunt the effects,11 and stopping an antidepressant carries its own risks.12 Only 8 of 36 calculators name lithium.1
Mind and setting: not a number at all
In a pooled analysis of 409 psilocybin sessions in 261 volunteers, dose was the strongest predictor of the experience, but a scanner setting predicted anxiety more than twice as strongly as dose did, and the best model explained 31% of the variation.7
We checked 36 calculators: here's what they leave out
We read every web calculator we could open for magic mushrooms, truffles and tolerance and recorded what each page asks for and tells you. We didn't record a single dose output. Half of them, 18 of 36, are run by companies that sell psilocybin or mushroom products.1
- Require body weight23 of 36
- Warn that potency varies19 of 36
- Mention medication interactions15 of 36
- Name lithium8 of 36
- Mention psychosis or bipolar history6 of 36
- Cite any research5 of 36
- Give a help or crisis line3 of 36
Check these before any calculator
- Interaction checkerType a medicine and see what the research says, from lithium and SSRIs to stimulants, with sources.
- Who should avoid itWhat psilocybin trials exclude and why: heart, blood pressure, mental-health history, pregnancy.
- Potency dataLab measurements from 42 published sources, as range bars and a free download.
If something goes wrong
Call 911 for chest pain, a seizure, trouble breathing, or someone who can't be woken. Poison Control answers at 1-800-222-1222, day and night.14 The 988 Suicide and Crisis Lifeline takes calls and texts 24/7,13 and the Fireside Project offers free peer support for difficult psychedelic experiences at 62-FIRESIDE (623-473-7433), 11 a.m. to 11 p.m. Pacific.8 Read the help page.
Latest research and rule changes
- Oregon's draft psilocybin rules add a new potency line to product labels
Oregon's draft rules add a total psilocybin equivalent label line and, under HB 4040, split dose reporting.
- Oregon proposes changing the formula labs use to total psilocybin potency
Oregon labs would report "total psilocybin equivalent" instead of "total potential psilocin".
- Microdosing meta-analysis finds no clear benefit over placebo in healthy adults
Pooled randomized trials showed no significant effect on depression, anxiety or stress scores versus placebo.
- Fourteen Psilocybe cubensis strains grown the same way differed almost tenfold in psilocybin
A 2026 study of 14 cubensis strains found psilocybin varied 9.66-fold, and single mushrooms of one strain differed too.
Every guide
- We checked 36 online mushroom dosage calculators: what they ask, what they leave out
- Psilocybin drug interactions: lithium, SSRIs, MAOIs and 23 more
- Who should avoid psilocybin? What clinical trials exclude
- Psilocybin potency: every magic mushroom lab measurement we could find
- Does body weight change how strongly psilocybin hits? What studies found
- Mushroom tolerance calculators: what they assume vs what's been measured
- Which magic mushroom strains are strongest? What lab tests show
- Does microdosing mushrooms work? What placebo-controlled studies found
- What does the mg on a mushroom capsule label mean?
- Psilocybin vs psilocin: what's the difference?
- Can you overdose on magic mushrooms? Toxicity, poison center data and warning signs
- Bad trip help: what to do and who to call
- Psilocybin glossary: terms from calculators, lab reports and studies
Questions people ask
Is there an accurate magic mushroom dosage calculator?
Not in the sense of knowing your result. Every calculator multiplies by an assumed potency, and lab studies keep finding severalfold differences between strains, batches and even single mushrooms. The more honest tools state their formula and the potency they assume, warn about medicines and give a help line; our calculator check shows which ones do.
Why do calculators ask for body weight?
Most borrow the idea from drugs that are dosed by weight. For psilocybin, a pooled analysis of 288 trial participants found no evidence that weight affected the subjective effects, and recent clinical trials gave everyone the same fixed amount.
Why doesn't this site give doses?
Because a number without the potency, your medicines and your health history is a guess presented as a measurement, and psilocybin is illegal under federal law. We publish the evidence calculators leave out instead: potency data, interactions, and who trials exclude.
Who runs this site?
The team that runs My Mushroom Dispensary, an online shop for adults 21+. We say so on every page that mentions it and in About. We sell no advertising.
Sources
- Online magic mushroom dosage and tolerance calculators audit. Magic Mushroom Dosage Calculator, checked October 26, 2026 (data under CC BY 4.0).
- Sharchaton A, et al. Surprising variability in tryptamine profiles of Psilocybe cubensis fruiting bodies: inter- and intra-strain differences across 14 strains cultivated under controlled conditions. Journal of Fungi, 2026;12(7):486. PMID 42506248.
- Garcia-Romeu A, et al. Optimal dosing for psilocybin pharmacotherapy: considering weight-adjusted and fixed dosing approaches. Journal of Psychopharmacology, 2021;35(4):353-361. PMID 33611977.
- Spriggs MJ, et al. Body mass index (BMI) does not predict responses to psilocybin. Journal of Psychopharmacology, 2023;37(1):107-116. PMID 36373934.
- Nayak SM, et al. Classic psychedelic coadministration with lithium, but not lamotrigine, is associated with seizures. Pharmacopsychiatry, 2021;54(5):240-245. PMID 34348413.
- Isbell H, Wolbach AB, Wikler A, Miner EJ. Cross tolerance between LSD and psilocybin. Psychopharmacologia, 1961;2:147-159. PMID 13717955.
- Studerus E, et al. Prediction of psilocybin response in healthy volunteers. PLoS One, 2012;7(2):e30800. PMID 22363492.
- Fireside Project: psychedelic peer support line. Fireside Project, checked October 26, 2026.
- McTaggart AR, et al. Domestication through clandestine cultivation constrained genetic diversity in magic mushrooms relative to naturalized populations. Current Biology, 2023;33(23):5147-5159. PMID 38052161.
- Beug MW, Bigwood J. Psilocybin and psilocin levels in twenty species from seven genera of wild mushrooms in the Pacific Northwest, U.S.A. Journal of Ethnopharmacology, 1982;5(3):271-285. PMID 7201053.
- Gukasyan N, et al. Attenuation of psilocybin mushroom effects during and after SSRI/SNRI antidepressant use. Journal of Psychopharmacology, 2023;37(7):707-716. PMID 37291890.
- Henssler J, et al. Incidence of antidepressant discontinuation symptoms: a systematic review and meta-analysis. Lancet Psychiatry, 2024;11(7):526-535. PMID 38851198.
- 988 Suicide and Crisis Lifeline. Checked October 26, 2026.
- Poison Help, 1-800-222-1222. Health Resources and Services Administration. Checked October 26, 2026.
Written and checked by the Dosage Calculator editors. Magic Mushroom Dosage Calculator is published by the team that runs My Mushroom Dispensary, an online shop. We sell no advertising and nothing on this site. Read who we are and how we check facts.