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How Do You Test THC Levels in Cannabis?

Quick – what was the THC content of the last joint you smoked? 15%? 20%? 25%? Do you know? Can you be sure? Probably not, in truth. It’s a fact that most of us have no idea what the THC content of our cannabis is.

You may be going by your budtender’s word, or if you grow yourself, by the promise on the packet. For what it’s worth, there’s a degree of accuracy to that, but how do you test THC levels of cannabis to be absolutely certain?

It would be nice if there was a way you could carry out potency testing at home. After all, if you grow your own marijuana and smoke your own marijuana, ideally, you’d be able to run your own tests.

Fortunately, there are a few ways to carry out cannabinoid testing.

What is THC?

THC is the abbreviation for tetrahydrocannabinol, the primary psychoactive cannabinoid in the cannabis plant. THC is found in the resin produced by the plant and can be smoked or extracted from the flower to make other cannabis products.

 Test THC Levels

The THC level of cannabis determines its potency; the higher the percentage, the more potent the weed. Upon ingestion – whether inhaled, eaten, drank or ingested in other way, THC molecules bind to the endocannabinoid receptors we each have in our bodies and brains. When that happens, we can experience a range of effects.

How Does THC get you High?

The body’s endocannabinoid system is a molecular system that helps the body maintain functional balance.  It regulates key functions like appetite, memory, sleep, and much more. If you’ve ever consumed cannabis, you’ll most likely have noticed it affects all of these things. It works via a series of cannabinoid receptors on the surface of cells in the human body, and when cannabinoids bind to these receptors, they trigger a body response.

The two main cannabinoid receptors are:

CB1 – present in the central nervous system

CB2 – present in the peripheral nervous system and immune system

During cannabis use, THC binds to the CB1 receptors, causing the body to recognise intoxication and causing it to make a series of adjustments to cope. Bloodflow to the brain’s prefrontal cortex is increased, affecting decision-making, motor skills, attention span and more.

Specifically for cannabis users, feelings of euphoria are triggered in the brain’s reward centre, creating a state of happiness. Congratulations, you’re stoned!

Why Should You Test THC Levels of your Cannabis?

If you’re someone who’s happy to spin the wheel and see where it lands, you’re probably not that concerned with running tests on your weed to see how potent it is.

That’s fine, of course, but there are several reasons why it’s a good idea to test the THC content of your cannabis.

You’ll Know What to Expect

Whether you’re new to cannabis or not, it can help to know how potent weed is beforehand. If it’s really high in THC, you may want to designate it for evening-only use, or if it’s lower in THC, you can mark it as safe for daytime consumption.

Helps you Analyse your Cultivation Habits

Testing can help you identify where you went right or wrong during cultivation if you grew your own.

For instance, if your buds score higher than the advertised levels of THC, make a note in your grow diary because you’ve probably handled things extremely well regarding nutrient levels, lighting, flowering time, etc. Likewise, if your buds register well below advertised, it may indicate room for adjustments in your cultivation approach.

Makes Dosing Easier

Especially true for users of medical cannabis, if you know your THC content, it can help you dose accurately and avoid any overdosing and the feelings of intoxication that go along with it.

How do you Test THC Levels in Cannabis?

We know what THC is and how it affects us. The more THC we consume, the more pronounced those effects will become. Depending on your tolerance levels, you’ll either be able to handle higher amounts of THC or only lower doses.

You’ll have a good idea of which of these is you, and it’s most likely a matter of experience – regular puffers will have a higher tolerance, newbies and occasional tokers will find their tolerance much lower, meaning it doesn’t take much THC to upset the applecart.

The beauty of legal cannabis dispensaries is that they’re required by law to ensure the weed is lab-tested before it hits the shelf, so stated THC percentages will be pretty accurate. But say you’ve just acquired a few buds and want to check their potency.

How do you test the THC levels in your cannabis?

Home Testing Kits

These are available in different forms and range in price from the fairly cheap to the considerably more expensive. Naturally, the more you spend on a test, the more accurate it will likely be. If you have a local dispensary, you can likely pick one up from there.

Otherwise, you can order one online.

Some kits can test for all manner of content, including cannabidiol (CBD), THCV, THCA, CBG, and other cannabinoids. If that’s of interest to you, great, but if you’re looking to test purely THC levels, pick up a kit which does THC alone.

By choosing a THC-only test, you immediately remove layers of complication and make it far more straightforward to carry out testing.

How to use a Home THC Test Kit

Choose the strain you want to test, and make sure it hasn’t been in close contact with any other cannabis strains – otherwise, you risk a false reading. All kits differ in one way or another, but they do come with instructions, so follow them closely to improve your chances of an accurate result.

Take a small sample of cannabis and break it up into even smaller pieces until you have about one-fifth of a gram for your test sample. The instructions will tell you how much to use for testing, so it helps if you have a good set of scales to weigh out the correct amount.

 Test THC Levels

Most test kits will come with a vial – a small plastic tube with a lid. You’ll put your cannabis in the vial, add the testing solution from the kit, seal and shake. Follow the instructions to know how long to leave the cannabis in the solution for it to react, and once the time is up, you should be left with a different coloured solution in the vial than you started with.

Home tests usually come with a colour chart, and at the end of the test period, you’ll check the colour of the sample in your vial against the colour chart.

From here, you should be able to match your sample to an approximate potency level. Most home kits don’t give you a percentage of THC content. It’s as simple as that, but as stated, the accuracy of home testing kits is unlikely to be 100%.

Home TLC Kits

TLC, or thin-layer chromatography, is a more accurate, complex, and expensive way to test the THC levels of your cannabis at home. They’re the next level up in price, usually starting at over $100, but TLC kits provide a good deal more bang for your buck. You can test many more samples and cannabinoids than a standard home THC testing kit allows.

 Test THC Levels

Using a TLC kit is a bit more sophisticated than a THC kit. You’ll mix a very small amount of your cannabis (in whatever form, i.e. flower, edible, concentrate) with a solution and then drip it onto the glass plate provided with the kit. 

Afterwards, you’ll carefully position the plate in a jar of test fluid and spray the plate with the included dye. You’ll see coloured dots appear and compare them to the chart, including determining the amount of THC (or whichever cannabinoid you’re testing for) in your cannabis. The real beauty of TLC kits is that they’re often accurate to around 1%, so the reading you get from the test is pretty darn close.

Order one for yourself here.

Testing Devices

If you’re really serious about this and plan to test every strain you buy or grow, you can break the bank and treat yourself to a handheld cannabis testing device. Don’t expect too much change from a grand, though – and bear in mind this pro-level kit is aimed at breeders and larger-scale cultivators.

 Test THC Levels

The next level up in sophistication, you place a quantity of cannabis flower in the device, then pair the device to your smartphone through Bluetooth. Set the software to tell it what you want to test for, and wait around five minutes for it to analyse your sample. When it’s done, you’ll get a fairly comprehensive readout of the contents of your cannabis, including THC, CBD, CBN, and even the terpenes present in your strain.

Order yourself a Gemmacert Testing Kit here.

THC Lab Testing

Admittedly, getting your weed lab-tested is difficult – finding a facility with the appropriate equipment is hard enough, but finding one that accepts public samples is even harder. If you’re lucky enough to get that far, you will have some serious resources at your disposal to play the game. Lab testing THC can cost upwards of $100 per sample, so it’s more of a commercial-level way of testing marijuana.

Lab testing involves a more advanced level of liquid chromatography to analyse weed, but it’ll give you high-level accuracy on your THC potency and provide terpene information. In some cases, lab testing also comes with a safety analysis of your cannabis samples and will give you details of everything from pesticides and heavy metals to microbes in the test results.

Is Testing THC Content Worthwhile?

Ultimately, the answer to this question varies from person to person. If you’re a recreational or medical cannabis user and you’re curious, you don’t need to drop vast sums of money to get an approximate indication of the THC content of your pot. However, if you insist on accuracy, it will cost you a pretty penny to scratch that itch with any degree of real precision.

Three High THC Cannabis Strains Try

If you’re looking to level up and sample cannabis with a high THC content, Seedsman can spoil you for choice. We have some of the highest-THC strains available today, and these can be yours to try with just a few clicks. Head over to to see more, but in the meantime, here are three of the best High THC cannabis seeds around:

Purple Ghost Candy

With a THC content of 27%, Seedsman’s Purple Ghost Candy has set tongues wagging throughout the cannabis community for its potency. But there’s so much to this elite strain than the THC content alone.

We crossed Candyland Purple with Ghost OG and came up with a new sativa-dominant hybrid – the kind of killer cannabis you owe yourself to try. And as you’d imagine, the effects of a strain so high in THC are next-level bliss. It’s cerebrally stimulating and will charge up your social presence but has an intensely relaxing effect on the body, one that soothes and nurtures any aches, pains and stress.

 Test THC Levels

The taste profile of this show-stopping strain is just as impressive – lemon-lime and peach notes abound, with a crisp mint bite on the exhale. It’s spicy, earthy, and fruity all at once, and cannasseurs can’t get enough.

Purple Ghost Candy is an easy-growing, high-yielding superstar cannabis strain. After 12 weeks of flowering, indoor growers can reap 500-600gm/m2 of high-THC bud. Outdoor growers can expect between 700-900gm/plant.

Try Purple Ghost Candy feminised seeds today

Gelat OG

If Indicas are more your thing, help yourself to a scoop of the delicious high-THC Gelat OG. This fast-flowering favourite packs a considerable punch with 25% THC and minimal CBD content below 0.1%. The result? Cannabis par excellence.

Gelat OG is a piece of cake to grow and recommended for beginners – although seasoned cultivators will know how to coax the very best out of these plants. Crossing OG Kush with Gelato gave us a plant with phenomenal resin production, making it a winning pick for makers of extracts and concentrates. Gelat OG has a short flowering period of just 9 weeks, meaning you won’t have long to wait to sample all the magic this one has to offer.

Sweet citrus and earthy floral notes mark the taste and perfume of Gelat OG, making it a sumptuous smoke with a tangy taste. The effects from the 25% THC may be surprising, though – rather than the couch-lock sensation you may expect from a potent indica, Gelat OG delivers high levels of relaxation and contentment but with a happy and uplifting buzz.

Pick up Gelat OG feminised seeds from Seedsman today

Zkittlez Auto

If you’re looking for a high-THC strain but with the convenience of autoflowering properties, look no further than Seedsman’s own Zkittlez Auto. Its 24% THC content is pretty impressive!

This is a sensational experience for the taste buds, being a cross of two of the fruitiest strains around – the legendary Zkittlez and a Fruit Kush Auto. If you’re growing Zkittlez Auto indoors, take great to ensure your odour control is on point to handle the insane aroma of these amazing plants. She’s a thirsty one, so make sure to keep her topped up with water and nutrients to get the best results. Zkittlez Auto flowers in 13 weeks, yielding up to 500gm/m2 if grown indoors and up to 600gm/plant outdoors.

The taste of this mostly-sativa hybrid is where it really shines. Sweet candy, berries, and grapes are all to the fore in the delicious Zkittlez Auto. You’ll find feelings of happiness and euphoria, but at the same time, supreme body relaxation. Zkittlez Auto has earned a reputation as medical marijuana and has been touted as successful in relieving pain, insomnia and depression.

Try the high-THC Zkittlez Auto today. Buy Feminised seeds from

Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

Duncan Mathers