Who makes this
This site is independently built and maintained. It is free, has no accounts, and stores nothing on a server — your inputs live in the URL of your own browser, which is also how the share links and QR codes work. Corrections are genuinely welcome at hello@ediblecalculator.app.
This is a calculation tool, not medical advice, and not a substitute for lab testing. If an exact dose matters to you for a medical reason, test your material.
The constants
The 0.877 THCA to THC factor
Decarboxylation removes a carboxyl group from THCA and releases carbon dioxide. The mass that leaves is real, so the conversion is not one-to-one:
- THCA (C₂₂H₃₀O₄): 358.47 g/mol
- THC (C₂₁H₃₀O₂): 314.46 g/mol
- Ratio: 314.46 ÷ 358.47 = 0.8772
This is the same factor used across the cannabis testing industry to report Total THC as (THCA × 0.877) + THC. CBDA to CBD uses the same molecular weights and therefore the same ratio; CBGA to CBG is marginally different at 0.878.
Why this matters: a calculator that converts THCA to THC one-to-one overstates potency by about 14%. On a 10mg target that is 1.4mg — not dangerous. On a 50mg batch portion for someone who is sensitive, it is the difference between the dose they planned and the dose they got.
Infusion efficiencies
The 75–90% range used here reflects widely reported home-infusion outcomes rather than a controlled study, and the spread between carriers tracks their saturated fat content, since cannabinoids are lipophilic. These are the softest numbers in the whole tool. If you have tested your own infusion, override the value in the fine-tune panel — your measurement beats our estimate every time.
The decarboxylation model
Decarboxylation is first-order, and first-order rate constants follow the Arrhenius relationship, so ln(time) is linear in 1/T. The calculator fits that line to the time and temperature pairs that home-decarb guidance has settled on:
| Temperature | Celsius | Modelled time |
|---|---|---|
| 220°F | 104°C | 65 min |
| 240°F | 116°C | 39 min |
| 250°F | 121°C | 30 min |
| 265°F | 129°C | 21 min |
| 280°F | 138°C | 15 min |
Two limitations worth stating plainly:
- The published anchors are rules of thumb and are not mutually consistent, so the fit reproduces them to within roughly 14% rather than exactly.
- The implied activation energy (~57 kJ/mol) is lower than laboratory kinetics for isolated THCA. That is expected: oven guidance absorbs preheat lag, tray depth and thermal mass that a sealed vial does not.
Treat the output as a calibrated starting point, not a lab protocol.
What this cannot tell you
The arithmetic is exact; the inputs are not. Home ovens run up to 25°F off their dial, infusion efficiency shifts with time and agitation, cannabinoid distribution through a finished batch is rarely uniform, and lab-reported potency has its own error bars. A realistic envelope around any figure here is about ±20%.
That uncertainty is a reason to round your dose down, not up. Take half a serving, wait two hours, and decide from there.
Changes
- August 2026 — Added the 0.877 molar conversion factor, which was previously missing entirely. Added an explicit Total THC / THCA basis toggle, input bounds, and a single shared definition of the dose tiers. Corrected decarb efficiency so it applies on both bases: an earlier revision skipped it for Total THC readings on the mistaken view that the label already accounted for it, which overstated potency by about 10% at the default setting. Material that arrives already decarboxylated is exempt.