You should be able to pick up a cannabinoid test kit at your local clinic or dispensary. If you don’t have one of these places in your area, try looking online. Home test kits typically sell for between $20-100, depending on the level of precision you’re looking for.

Only test one type of cannabis at a time. Make sure the strain you’re testing hasn’t been in contact with any other strains—this could throw off your reading. In most places where marijuana is legal, vendors are required by law to provide the cannabinoid content for the strain they sell. However, this is not always the case. Home testing is a good way to learn more about a certain strain before you put it in your body.

Most kits contain multiple tests, which can give you a second chance if you make a mistake the first time around.

Break up large clumps to allow the sample to fit inside the vial and infuse into the testing solution. A pair of tweezers may come in handy for handling tiny test samples.

Basic test kits tend to only call for about 1 ml of fluid, while more sophisticated systems may require as much as 15 ml. [5] X Research source If your kit came with more than one testing solution, make sure you add each in the correct proportion.

Hold your thumb over the lid of the vial while you shake it to keep it from coming open accidentally.

After a few minutes, the solution will slowly wick up the slide, separating the various compounds into distinct, easy-to-read layers. [8] X Research source Slide tests are more nuanced and are designed to make the color-coded results easier to interpret. They are often used with combination kits.

Let the sample sit for the full 10 minutes. If you check it before it’s had enough time to reach its final shade, the resulting reading will be incorrect.

Color charts will usually be labelled to indicate a range of potency rather than an exact percentage. For example, a sample that comes back light blue may contain only 5% THC, while one that’s royal or navy blue might be closer to 20%. If you’re using a slide test, make sure you’re looking at the layer that corresponds to THC to avoid confusing the reading for that of another compound. [10] X Research source

Look up drug screening labs in your area to find out if there’s somewhere you can go to have a blood or saliva sample taken. If you live in Australia, you might be able to purchase a home saliva-testing kit to check your THC levels. [12] X Research source

In most parts of the world where THC is labeled as a controlled substance, the acceptable legal concentration you’re looking for is 5 nanograms per milliliter of blood or less. [14] X Research source Because of how rapidly THC breaks down in the body, a fresh sample will usually have deteriorated before it can be processed.

It’s difficult even for most researchers to interpret the effects and lifespan of THC in the body.

You could be subjected to a hefty fine or even jail time for the unlawful purchase, possession, or use of marijuana. [16] X Research source