What heat does to each cannabinoid

THCA C22H30O4 → THC C21H30O2 + CO₂1 g of THCA leaves 877 mg of THC

Made by the plant from CBGA, and present in raw flower almost entirely as the acid.

The one every number on this site is about. Raw flower carries THCA, which does nothing until heat drives off a molecule of carbon dioxide and leaves THC behind. Keep heating past that point and you start losing it again — not to evaporation, but to CBN, which is why every temperature ceiling in the decarb table sits where it does.

Degrades to CBN slowly, through heat, oxygen and time — and never back again.

CBDA C22H30O4 → CBD C21H30O2 + CO₂1 g of CBDA leaves 877 mg of CBD

Also made from CBGA, by a different enzyme. A plant leans one way or the other; it does not make both freely.

Behaves almost exactly as THC does through the oven, which is convenient: the same decarb schedule converts both, and the mass it loses on the way is identical because CBDA and THCA are built from the same atoms in a different arrangement. What it does not do is turn into CBN. That degradation path belongs to THC alone, and the two get conflated constantly.

CBGA C22H32O4 → CBG C21H32O2 + CO₂1 g of CBGA leaves 878 mg of CBG — -1 mg less than this site’s calculators assume

The one the others are made from. CBGA is the plant's starting material, and enzymes convert most of it into THCA or CBDA as the flower matures — so a mature plant has little left, and the lines that keep it are the ones bred not to convert it.

Decarbs like the rest, at very nearly the same ratio. The reason you rarely have much of it is agricultural rather than culinary: the plant spent it becoming something else before harvest.

CBCA C22H30O4 → CBC C21H30O2 + CO₂1 g of CBCA leaves 877 mg of CBC

A third branch off CBGA, usually a minor one.

Same atoms as THC and CBD in another arrangement, so it loses the same fraction of its mass decarbing. Present in small amounts in most flower and rarely reported on a label at all, which means you are usually cooking with some and have no figure for it.

CBNA C22H26O4 → CBN C21H26O2 + CO₂1 g of CBNA leaves 876 mg of CBN — 1 mg less than this site’s calculators assume

Not really made by the plant. CBN is what THC becomes after enough heat, air and time — so its presence is a record of what happened to the material rather than of how it grew.

This is the one to read as a signal. A lab sheet with meaningful CBN on it is telling you the flower is old, was stored badly, or was cooked too hard — and every milligram of it was THC once. That conversion is one-way. It is also why old butter tests weaker than the day it was made, and why 'longer is safer' is the most expensive wrong idea in this subject.

THCVA C20H26O4 → THCV C19H26O2 + CO₂1 g of THCVA leaves 867 mg of THCV — 10 mg less than this site’s calculators assume

Built on a shorter side chain than THC — three carbons instead of five — from a different precursor acid. Concentrated in some African and Asian landrace lines and scarce almost everywhere else.

Decarbs like the others, but the arithmetic is not quite the same. Because the molecule is smaller, the carbon dioxide it sheds is a larger share of its mass, so less of the acid survives as the neutral form than the figure this site's calculators use.

CBDVA C20H26O4 → CBDV C19H26O2 + CO₂1 g of CBDVA leaves 867 mg of CBDV — 10 mg less than this site’s calculators assume

CBD's short-chain counterpart, and as uncommon as THCV.

Shares THCV's arithmetic exactly, for the same reason: same atoms, different arrangement. If a label gives you a varin figure, the conversion to expect off the acid is a little lower than the one the calculators here assume.