THCA vs THC: what the difference means
THCA is the form of THC the plant makes. Heat turns it into THC. Here is what that means for labels, total THC and what you are buying.
Key points
- The plant mostly holds THCA; THC forms when THCA is heated.
- A label may list THC, THCA and total THC as three separate numbers.
- Total THC is calculated, not added: THC + (0.877 × THCA) under Washington's rule.
THCA is the acidic form of THC that the cannabis plant produces. Heat converts it into THC, the compound with intoxicating effects, which is why flower with a low THC number and a high THCA number is still strong once it is smoked, vaped or baked.
What is THCA?
THCA (tetrahydrocannabinolic acid) is the acid form of THC. A 2016 laboratory study explains that the neutral cannabinoids such as THC "do not occur in significant concentrations in cannabis" and are formed from their acid forms, which are "the predominant cannabinoids in the plant."
Wang et al., Cannabis and Cannabinoid Research
THC is the compound the National Institute on Drug Abuse describes as having "intoxicating — mind altering — effects." So the practical question for any product is how much THC it will deliver once it is used, not only how much THC it holds in the jar.
How does THCA become THC?
Through heat. The process is called decarboxylation: the acid group breaks off and THCA becomes THC. The study above measured it by heating extracts at set temperatures from 80°C to 145°C for up to an hour.
Lighting a joint, using a vaporizer and baking flower before making edibles all apply that heat. This is why raw flower and the same flower after heating are chemically different products.
THCA vs THC at a glance
| THCA | THC | |
|---|---|---|
| What it is | The acid form the plant makes | The form produced when THCA is heated |
| In raw flower | Most of the total | A small share |
| On a lab report | Listed as THCA | Listed as delta-9 THC |
| After smoking, vaping or baking | Converted to THC | The compound with intoxicating effects |
| In the total THC figure | Counted at 0.877 of its weight | Counted in full |
What does total THC mean on a label?
Total THC estimates how much THC a product can deliver after heating. Washington's testing rule sets the calculation as delta-9 THC + (0.877 × delta-9 THCA). The 0.877 accounts for the weight THCA loses when it converts.
A worked example: flower testing at 1% THC and 20% THCA has 18.54% total THC, not 21%. States define total THC in their own rules, so compare numbers within one state's labels. Our guide to THC, total THC and potency labels goes through the label line by line.
What is THCA flower?
"THCA flower" is a sales term for cannabis flower sold under hemp rules on the basis of its low delta-9 THC number. Whether that is lawful depends on how a jurisdiction counts THC, and those rules differ by state and are changing federally.
Because the law is moving, check the current position for your state on our cannabis laws by state pages and the federal picture on federal status before relying on anything printed on a package.
Common questions
Is THCA the same as THC?
No. THCA is the acid form the plant makes; THC is what it becomes when heated. They are listed separately on a lab report.
Does THCA get you high?
THC is the compound with intoxicating effects, and THCA converts to THC when it is heated. Flower high in THCA therefore delivers THC when it is smoked, vaped or baked.
What is a good THCA percentage?
For flower, THCA makes up most of the total THC figure, so read it the same way. See our guide to what a good THC percentage is.
Why is the THC number on my flower so low?
Raw flower holds most of its THC as THCA. Look for the total THC line, which combines the two using the state's formula.
Sources and further reading
Kush is for adults 21+. This guide is educational; product rules and testing requirements vary by state. Our editorial standards & corrections policy.
