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Consumer guide

How to read a certificate of analysis (COA)

A certificate of analysis (COA) is a lab report for one batch of a product. To read one, first make sure it matches the batch number on your package. Then check who tested it and when, read the THC numbers, and look for a result on every safety test.

By CHSA editorial team · Published

Checked against California's testing law and regulations on . Next review: .

Fig. 1 · Specimen diagram · California

Reading a certificate of analysis (COA)

Specimen COA for a generic edible. Not a real lab, product or result.

[Testing laboratory name]Certificate of analysis

[City], CA · Report [0000-0000] Lab license [Lab license no.]

Sample [Product name] · Edible
Batch [0000-000]
Sampled · Reported [YYYY-MM-DD] · [YYYY-MM-DD]
Cannabinoids · 4 CCR § 15724
Analyte Result Per serving Per package
Δ9-THC [0.00] % [00.0] mg [000] mg
THCA [0.00] % [00.0] mg [000] mg
Total THC [0.00] % [00.0] mg [000] mg
CBD [0.00] % [00.0] mg [000] mg
Required safety screens · 4 CCR § 15714(b)
Category 4 CCR § Lab result
Residual pesticides 15719 Pass
Heavy metals 15723 Pass
Microbial impurities 15720 Pass
Mycotoxins 15721 Pass
Residual solvents and processing chemicals 15718 Pass
Foreign material 15722 Pass
Moisture · water activity 15717 Pass
Terpenoids (only if applicable) 15725 NT

Specimen for illustration. All results are placeholders. Page 1 of [n].

  1. Is the lab licensed? California labs must hold a state license, and the COA must show its number. Look it up in DCC’s license search. B&P § 26100 · 4 CCR § 15726(e)(2)
  2. Does the batch match? The batch number must match your package. A COA for another batch says nothing about yours.
  3. Check the dates. The COA must show when the sample was collected, when the lab received it and when it was tested. 4 CCR § 15726(e)(7)
  4. Look at total THC. Total THC = THC + (0.877 × THCA). Edibles: THC per serving must be within 10% of 10 mg. 4 CCR § 15724(c)(4) · B&P § 26100(e)(3)
  5. What “Pass” means. The sample met California’s limit for that test when it was tested. It is not a safety guarantee or a CHSA finding. Terpenoids are tested only if applicable (§ 15725).

Sources: Required test categories: Cal. Code Regs. tit. 4, § 15714(b) · COA contents and total THC: Cal. Code Regs. tit. 4, §§ 15724(c), 15726 · Edible tolerance: Bus. & Prof. Code § 26100(e)(3) · Retrieved · CHSA. “Pass” is a lab finding, not a CHSA verdict. CHSA does not test, certify or endorse products.

Five steps: match the batch, check the lab, check the date, read the THC numbers, and check every safety test. If you cannot find a COA for a product, or it does not match, that is worth asking about.

This guide uses California’s rules as the example. In California, a licensed lab must test cannabis before it is sold and issue a certificate of analysis.1

Step 1: Make sure it is the right report

A COA covers one batch. Find the batch or lot number on your package and on the COA. They should match exactly. Also check that the product name and type match, such as flower, vape or gummy.

Step 2: Check who did the testing

In California, the lab must hold a state license.1 The COA must show the lab’s name, address and license number.2 You can look up the license in the Department of Cannabis Control’s (DCC) license search, which lists the businesses DCC licenses.3

Step 3: Check the dates

In California, a COA must show when the sample was collected, when the lab received it and when it was tested.2 A very old report may not reflect the product you are holding.

Step 4: Read the cannabinoid numbers

COAs show cannabinoids such as THC, THCA, CBD and CBN.12 Numbers may be in percent (%) or milligrams per gram (mg/g):

  • 1% is the same as 10 mg per gram.
  • For edibles, look for mg per serving and per package.

California COAs also show total THC when it applies. THCA turns into THC when it is heated, so total THC counts both. The rule sets the math: total THC = THC + (0.877 × THCA).2 This assumes all of the THCA turns into THC, so it gives the most THC the product could have.4 In California, the THC in an edible serving must be within 10% of the 10 mg target.1

Step 5: Check every safety test

Look for a result for each test the state requires. In California, that means pesticides, solvents, heavy metals, germs, mold toxins, moisture and foreign material.2 California COAs must show “pass” or “fail” for each test and an overall “pass” or “fail” for the batch. You may also see “ND” (not detected), “<LOQ” (found, but too little to measure exactly) or “NT” (not tested).2

If a test is missing, or says “Fail,” ask the seller. See what California tests for for what each test means.

Warning signs

  • No batch number, or a batch number that does not match your package.
  • A COA for a different product, or one with no lab name or license number.
  • Numbers or text that look edited.
  • A link or QR code that leads to a website that is not the lab’s.

What a COA cannot tell you

A COA reports on a sample from one batch. It does not test every package. Passing state limits does not mean a product has no risk. Products that passed testing can still be recalled. Check current alerts and recalls.