A California certificate of analysis (COA) is the lab report for one batch. Before reading any number on it, confirm it belongs to the batch in your hand. Then check which results it actually contains, because a potency table by itself is not the whole report.
This guide covers California only and describes what the state's published guidance says. It isn't legal advice.
Match the report to the package
The label gives you the anchors. The Department of Cannabis Control's labeling checklist for manufactured products requires a batch or lot number, a UID tracking number, the manufacturer's name and contact information, and a packaging date on the informational panel.
- Find the batch or lot number on the label and the batch identifier on the COA. If they don't match, the report describes some other product, however similar it looks; ask the retailer for the certificate that matches the batch number on your package.
- Check that the producer and product name agree.
- Note the date. Before goods go to retail, DCC's representative sampling checklist has the distributor confirm the COA is less than 12 months old. That's a check on the transfer to a store. It isn't an expiration date for your jar: an older report alone doesn't mean the product has gone bad, and a recent one says nothing about storage since testing.
- Compare the cannabinoid numbers. The label may round the COA's cannabinoid figure to the nearest whole number, and a THC or CBD result reported as "non-detect" or "below LOQ" shows up on the label as "0 mg" or "<2 mg." Small differences of that kind are expected.
The batch number is the strongest anchor. Once a batch passes, DCC says it can't be repackaged into a new production batch or assigned a new batch number.
See what the report covers
DCC's testing laboratories page lists the required testing categories:
- cannabinoids and terpenes
- residual solvents and processing chemicals
- residual pesticides
- heavy metals
- microbial impurities
- mycotoxins
- moisture content and water activity
- foreign material
According to the same page, the COA states whether the batch passes or fails for each substance. The cannabinoid results feed the required label figures; terpene figures appear on the label only if the producer lists them. The rest are compliance results. A single cannabinoid chart, a terpene graphic or a cropped screenshot doesn't show you those pass/fail lines.
A jar labeled solventless is still described on the label by how it was made. The COA reports what the lab measured.
What a pass means
A pass tells you that a sample from the batch met the state's standards for the categories tested, at the time it was tested. It says nothing about how your jar was stored since then, and it isn't a guarantee about every gram. DCC describes the purpose of testing as making sure goods are free of contaminants and accurately labeled.
The sample is drawn by a lab employee from the whole batch at the distributor's premises, with manufactured products and pre-rolls already in final retail packaging (flower may be sampled in bulk). The lab can't change a COA after issuing it without DCC permission. Failed batches are destroyed or, with an approved plan, remediated and retested.
Getting the report
Distributors must send a copy of the COA to every retailer that receives the batch, so a store may have it on file. These sources don't say whether a store must show it to you. If a QR code leads to a report, run the same batch match. DCC doesn't accept QR codes as a substitute for required label information, and a scan doesn't prove that the document belongs to your package.
For the rest of the package, see how to read rosin labels. For what a report can't tell you about enjoyment, see how to tell if rosin is good.