How to read a cannabis label (and its lab results)
Potency percentages, total THC math, terpene lists, and batch dates: a field guide to the fine print on legal cannabis packaging.
Updated July 7, 2026 5 min read
Legal cannabis comes with more label than most groceries. Once you can read it, the fine print answers the questions that matter: how strong, how fresh, what it will taste like, and whether it was tested.
Potency: THC, THCA, and totals
Flower labels usually show THCA (the raw form) and delta-9 THC separately, plus a "total THC" that applies the conversion math (THC + THCA × 0.877). Edibles list milligrams per piece and per package. Comparing products? Use total THC for flower and mg for edibles, and remember terpenes shape the feel as much as a few potency points.
Dates and batch numbers
Look for harvest or production dates: flower is at its best within 6-12 months, and terpene-forward products reward freshness. The batch number ties your product to its certificate of analysis (COA), the lab report behind the label, often reachable by QR code.
Reading the COA
A COA confirms potency and screens for pesticides, mold, heavy metals, and residual solvents. You mostly need two checks: the potency section should match the label, and every contaminant row should read "pass" or "ND" (not detected). A brand that makes COAs hard to find is telling you something.
Frequently asked questions
What does total THC mean on a label?
The THC you'll actually get after heating: delta-9 THC plus THCA multiplied by 0.877 to account for conversion loss.
What is a COA?
A certificate of analysis: the third-party lab report showing a batch's potency and contaminant screening results. Licensed products link each package to one by batch number.