A certificate of analysis (COA) is the lab report for one production batch of a CBD product. To read it, check four things: the batch number matches your bottle, the date of analysis, the CBD result compared with the label, and the THC result compared with the stated limit. Results are usually given in percent by weight, where 1% is about 10 mg per ml of oil, and "n.d." means not detected. At Formula Swiss, every production batch is tested, and the labels show the batch number and the CBD and THC content to two decimal places.
Key facts
- What a COA is
- The lab report for one batch, listing the measured cannabinoids
- First check
- The batch number on the report matches the batch number on your bottle
- Units
- Usually % by weight (wt.%). For an oil, 1% is about 10 mg per ml.
- "n.d."
- Not detected: below the lowest amount the method can measure
- THC
- Compare Δ9-THC (and Δ8-THC, if listed) with the limit on the label
- Why it matters
- In a test of 84 CBD extracts bought online, only 31% matched their label within 10% (Bonn-Miller et al., 2017)
What is a certificate of analysis?
A certificate of analysis is a document from a laboratory that shows what was measured in a sample from one production batch. For a CBD oil, the core of the report is the cannabinoid profile: how much CBD, THC and other cannabinoids the batch contains.
Because the report belongs to one batch, it only tells you about your bottle if the batch numbers match. A report for a different batch, or a report without a batch number, does not tell you what is in the bottle you hold.
The parts of a COA, one by one
| Part of the report | What it tells you | What to check |
|---|---|---|
| Report number | The reference of the analysis | Use it when you contact the seller about the report |
| Product and batch number | Which product and which batch was tested | It matches the batch number printed on your bottle |
| Date of analysis | When the sample was measured | It fits the production time of your batch |
| Method | How the cannabinoids were measured, for example GC-FID or HPLC | It affects how acid forms such as CBDA are reported (see below) |
| Results | Each cannabinoid, usually in % by weight | CBD is at least the amount on the label |
| THC | Δ9-THC, and on some reports Δ8-THC, listed separately | It is within the limit on the label, or "n.d." for a THC-free oil |
| Signature | Who is responsible for the report | The report is signed and dated |
How to convert percent into mg
Most reports give results in percent by weight. For an oil, 1% is about 10 mg per ml, because a ml of oil weighs close to a gram. So:
- A result of 10.28% CBD means about 103 mg CBD per ml, or about 1,028 mg in a 10 ml bottle.
- A result of 0.14% Δ9-THC means about 1.4 mg THC per ml.
To work out the amount per drop, divide the mg per ml by the number of drops per ml. Our CBD per drop guide has the tables for every strength.
A worked example: one of our certificates
Here are the results for St. Moritz Restore, one of our 30 ml full-spectrum oils (report 260410_A01, sample 260408.04, analysed in April 2026):
| Cannabinoid | Result | About mg per ml |
|---|---|---|
| CBD | 25.13% | 251 mg |
| CBG | 4.29% | 43 mg |
| CBC | 1.51% | 15 mg |
| CBN | 0.13% | 1.3 mg |
| Δ9-THC | 0.14% | 1.4 mg |
How to read it: the label promises 25% CBD, and the batch measured 25.13%, so the CBD is at or above the label. The label states THC under 0.2%, and the batch measured 0.14%. For comparison, the THC-free oils from the same report, Lucerne Calm and Lugano Clarity, show "n.d." for Δ9-THC. All results are in our guide to full spectrum, broad spectrum and isolate.
Why does CBDA not appear on some reports?
It depends on the method. Gas chromatography (GC) heats the sample, and heat turns the acid forms CBDA and THCA into CBD and THC. A GC report therefore shows the total after this conversion. Liquid chromatography (HPLC) does not heat the sample, so it can show CBDA and CBD separately.
Our certificates use GC-FID and state that the values "account for total amount of cannabinoids after complete decarboxylation". Our guide to CBDA and RAW CBD oil explains what this means for a RAW oil.
From our production
The certificates we publish come from our own lab in Switzerland, and I sign every one of them. We print the CBD and THC content on each label to two decimal places, for accuracy. When a label says 5% CBD, the oil contains at least 5% CBD, never less. For our full-spectrum oils, 99.9% of the batches declared under 0.2% THC measure between 0.12% and 0.17%, so there is a buffer to the limit.
Checklist: five questions to ask of any COA
- Is it for my batch? The batch number on the report matches the one on the bottle.
- Is the CBD at least what the label says? Compare the CBD result with the % or mg on the label.
- Is the THC within the stated limit? Full spectrum: below the figure on the label. THC-free: "n.d."
- Are the date and method stated? A report without a date or method is hard to interpret.
- Is it signed? Someone should be responsible for the result.
Some certificates also cover other analyses, for example for contaminants. Our quality control page describes the analyses in our testing process.
Frequently asked questions
What does COA mean on a CBD product?
COA stands for certificate of analysis. It is the lab report for one production batch and shows the measured cannabinoids, such as CBD and THC.
What does "n.d." mean on a lab report?
"n.d." means not detected: the amount is below the lowest level the method can measure. On a THC-free oil, the THC result should read "n.d."
How do I convert % on a COA into mg?
For an oil, 1% is about 10 mg per ml. A result of 10% CBD is about 100 mg per ml, or about 1,000 mg in a 10 ml bottle.
Why does the measured CBD differ slightly from the label?
Every batch varies a little, and every measurement has a small uncertainty. What matters is that the CBD is at least the amount on the label. Ours always is: a label that says 5% CBD means at least 5%.
Why is there no CBDA on my certificate?
Gas chromatography heats the sample, which turns CBDA into CBD. The CBD figure then includes the CBDA. Liquid chromatography can show the two separately.
Where can I find the COA for my bottle?
Look for the batch number on the label. Our certificates are published on our test results page, and if your batch is not listed, contact us with the product name and batch number and we will find the report.
Related guides
Formula Swiss CBD oils are sold as cosmetics for use on the skin. They are not food supplements or medicines and are not intended to diagnose, treat, cure or prevent any disease. This article is general information.
Last reviewed:
Sources
- Bonn-Miller MO, Loflin MJE, Thomas BF, et al. Labeling accuracy of cannabidiol extracts sold online. JAMA 2017;318(17):1708–1709. doi:10.1001/jama.2017.11909
- Wang M, et al. Decarboxylation study of acidic cannabinoids: a novel approach using ultra-high-performance supercritical fluid chromatography/photodiode array-mass spectrometry. Cannabis and Cannabinoid Research 2016. doi:10.1089/can.2016.0020
- Formula Swiss. Certificate of analysis, report 260410_A01 (sample 260408.04, St. Moritz Restore), published on our test results page.
- Formula Swiss. Quality control: guaranteed CBD levels, THC buffer and label information.
