How to Read a Lab COA for Cannabis

How do you know that the cannabis product you’re thinking about buying is high quality? A good start is to do some research and read up on reviews of products and businesses before you get to the buying stage. But there are always going to be new products hitting the market, and sometimes you just want to find out right there in the store.

Here at Gentleman Toker, it’s our mission to educate and empower cannabis users with the tools they need to make good purchasing decisions. So we're going to break down how to read a certificate of analysis (COA) for cannabis. 

What Does COA Mean?

Marijuana plants are excellent at absorbing nutrients, but this ability also means they are liable to pick absorb harmful materials if they are not properly grown and harvested. That’s why states require laboratories to test the products sold by cultivation centers and dispensaries for harmful substances, as well as their levels of THC and other cannabinoids.

A Certificate of Analysis is an informative label containing the test results for a particular cannabis product. The cannabis COA verifies that the product has undergone lab testing according to state standards and describes the specific results of the test. 

How Does Lab COA Testing Work?

While each state will have its own requirements regarding how a COA test is completed and what components it will test for, most cannabis COAs will have some of the same basic information. For example, a cannabis test could be required to test at least one sample from every batch of all marijuana products, including:

  • Flower
  • Tincture
  • Topical
  • Shatter
  • Oils
  • Edibles
  • Wax
  • Kief
  • Hash

To test for a broad spectrum of components, each sample is subjected to a battery of tests. In DC, COA cannabis tests often include:

  • Gas chromatography
  • Gas chromatography-mass spectrometry
  • Immunoassays
  • Thin layer chromatography
  • High-performance liquid chromatography
  • Liquid chromatography-mass spectroscopy

How Are COA Cannabis Tests Regulated?

State laws require the third-party laboratories that conduct cannabis testing to follow the testing methods approved by government agencies or scientific bodies such as the Research Institute of the AOAC International and American Herbal Pharmacopoeia.

How to Read a Certificate of Analysis

A COA cannabis test looks a bit like the back of a prescription bottle. It has a lot of very long words written in very tiny text with plenty of numbers and abbreviations thrown in for good measure. But there are a few key parts of the COA cannabis results that you can look at to quickly determine if this product may be right for you.

THC Levels

The first part of the cannabis COA you’ll probably want to zero in on is the THC content. This is usually the first number to be displayed on the COA tables. The COA should show a THC percentage, as well as a THC amount, measured in milligrams per gram (mg/g). 

Understanding the amount of milligrams of THC is important to understanding if you’re taking the right dosage for the intended effect. Each person is different, and the same levels of THC will have slightly different effects depending on your previous history and tolerance level. This is especially important if you’re new to cannabis. 

In our experience, however, the THC potency (represented by the percentage) isn’t as helpful as one might hope. It can be somewhat useful in directly comparing products to each other when there is a large difference, but at this point, the accuracy of testing for THC potency just isn’t there yet. 

Cannabinoid Content

After THC, you’ll want to check the additional amounts of cannabinoids, such as CBD and CBN, which are also represented in milligrams per gram. These indicators are usually more helpful in determining the strength of a product than the THC potency.

While businesses are legally required to test for a large number of items in a COA cannabis test, they may not be displayed on a label placed on the product. You can bet that THC content will be on there, but other items may be posted online and accessed through a QR code. Most phones nowadays will let you easily access the test results by simply turning on the camera function and holding it over the code. After it scans the code, a link will pop up to the cannabis COA test.

Other Important COA Data Points

Be sure to check out these items when reading a COA test for cannabis.

  • Testing lab name: This allows you to look up the lab and verify that it is legitimate.
  • Date of test: Are the results somewhat recent, or has it been on the shelf for a while?
  • Product brand name: Use this to make sure the COA results are actually for the product that you’re looking at and that the labels weren’t switched.
  • Toxins: Make sure each number is below the maximum allowed amount displayed, or that it says “passed.”

What’s Included in a COA for Cannabis?

As we mentioned earlier, different states will each have their own requirements for what should be included in a COA cannabis test. As an example, we have included what Washington, DC typically includes in its lab COA tests, such as:

  • Moisture content
  • Water activity
  • Cannabinoid potency, including (at minimum) the levels of Delta-9-tetrahydrocannabinolic acid (THCA), Delta-9-tetrahydrocannabinol (THC), Cannabidiolic acid (CBDA), Cannabidiol (CBD), and Cannabinol (CBN)
  • Foreign matter contamination
  • Microbial contamination
  • Mycotoxin contamination
  • Heavy metal contamination, including (at minimum) arsenic, cadmium, lead, and mercury
  • Pesticide and fertilizer residue
  • Residual solvents
  • Cannabinoid and terpene Profile
  • Product assessment (for edible products)
  • Homogeneity (for edible products)
  • Any other items requested by or approved by the U.S. Department of Agriculture

Many of the items listed above will be broken down into even further specificity on the COA cannabis test, which should include a list of all pesticides, heavy metals, fertilizers, and other harmful substances that were tested for. Foreign matter contamination sounds pretty vague, but it includes items like dirt, mold, rodent hair, insect fragments, “mammalian excreta”, and other substances you really don’t want in your products.

How to Know if a Lab COA Is Real

Unfortunately, there are a lot of fake cannabis COA tests out there, just like there are a lot of fake products. That’s why doing your research on each part of the COA test, such as the lab and product names, is crucial. The more legitimate COA cannabis tests you look at, the easier it will be to spot the fake ones. That’s why we’ve provided a few examples.

Certificate of Analysis Examples


Check Out Gentleman Toker’s Cannabis Reviews

While a cannabis COA can tell you what’s in a bud, it can’t tell you what it tastes like or what the high feels like. That's what Gentleman Toker is here for. Be sure to check out our reviews of cannabis strains and brands.