What THC Percentage Is High? What the Lab Data Shows

According to the Trimbos Institute in the Netherlands, cannabis with around 17% THC counts as high potency. The best-selling strains in Dutch coffeeshops average about 14.6% THC, and hash comes in around 21%.

Tetrahydrocannabinol, or THC, is the main psychoactive compound in cannabis, the one behind the euphoric high people feel. THC potency can vary a lot from product to product, from very low levels in some strains to extremely high concentrations in others.

What counts as a "high" THC level depends on several factors, including your experience, your personal tolerance and how you consume. Understanding THC levels is key to making informed, safe decisions about your cannabis use.

Why does dosing edibles accurately matter?

Working out THC doses in edibles correctly is essential to avoid nasty side effects and to handle the long wait before they kick in.

A common rookie mistake is assuming edibles won't be that strong because they're "just" made with flower. But taking too big a dose can leave you feeling really rough, and if that happens, the only fix is to wait it out.

What counts as a high THC percentage in weed?

A lot of cannabis users assume anything under 25% THC is weaker than average. But plenty of the cannabis grown and smoked out there sits around 15% THC. In the Netherlands, the Trimbos Institute, an authority on mental health and addiction, runs a yearly study on the potency of cannabis and hash.

The Trimbos Institute study

Trimbos's 20th annual survey, based on cannabis samples bought from 50 different coffeeshops, is a great example. At each shop, researchers bought the "strongest" strain and the "most popular" strain, then tested them for THC and CBD. That scientific approach to data collection is what makes the Trimbos study so useful.

What the study found

The study found that the top premium flower in the coffeeshops tested at 17% THC. Based on that evidence, around 17% THC counts as a high level for cannabis.

That's significant, because the Dutch coffeeshop system has been running for decades, supplied by professional growers working with reliable genetics. Still, a lot of people would have expected the top strains to clear 20% THC.

For comparison, the coffeeshops' most popular strains, meaning the best sellers, came in at 14.6% THC. The gap between popular and premium strains was only 2.4 percentage points. And the average THC in coffeeshop hash was 21%, just 4 points higher than top-shelf flower.

How other countries compare

The THC levels found by Trimbos are similar to what's been measured in the UK. A UK Home Office survey found average THC levels of 15% in cannabis samples seized by police. Practically all the cannabis in the UK is grown domestically, with very little imported.

The similarity between the UK's 15% average and the 14.6% in popular Dutch coffeeshop strains suggests that typical THC levels in UK cannabis probably sit around 15%.

The takeaway

In short, around 17% THC is considered a high level for cannabis, based on data from studies in the Netherlands and the UK.

A lot of users expect premium strains to top 20% THC, but the reality is that average THC levels in the weed people actually smoke are lower. That's why your sense of potency should be based on data, not assumptions.

How do you calculate the potency of edibles?

THC concentration in most cannabis products is measured as a percentage. For example, when you buy seeds at a grow shop, you might see numbers like 20% THC or 10% CBD.

When you make edibles, though, potency is measured in milligrams of THC. The conversion isn't super complicated, but it does take a few steps.

How to calculate THC doses in edibles

Getting the amount of THC in your edibles right is crucial to avoid unwanted effects. Here's how to do it, taking a few key factors into account.

Decarboxylation

Bud potency is listed as THC, but what's actually in the flower is mostly THCA (tetrahydrocannabinolic acid). Turning THCA into THC takes decarboxylation, or "decarbing," a process that uses heat.

Some THCA gets lost along the way. You'll usually keep somewhere between 75% and 88% of the original potency, but to keep the math simple, we'll use 90% here (a bit above that range, so treat the numbers below as an upper estimate).

Formula for calculating the amount of THC after decarboxylation:

1. Work out the weight of THCA per gram of flower:
   • 10% THC = 100 mg of THCA per gram of flower
   • 15% THC = 150 mg of THCA per gram of flower
   • 20% THC = 200 mg of THCA per gram of flower
2. Work out the total for 5 grams of flower:
   • 10% THCA: 100 mg × 5 = 500 mg of THCA
   • 15% THCA: 150 mg × 5 = 750 mg of THCA
   • 20% THCA: 200 mg × 5 = 1,000 mg of THCA
3. Work out how much THC you'll have after decarbing (90% efficiency):
   • 500 mg of THCA × 0.9 = 450 mg of THC
   • 750 mg of THCA × 0.9 = 675 mg of THC
   • 1,000 mg of THCA × 0.9 = 900 mg of THC

How efficient fat extraction is

Not all the THC will make it into your butter or oil, because the extraction process isn't 100% efficient. Efficiency can range from 30% to 60%; to be on the safe side for dosing, work with 60%.

Calculating the THC available to consume:

• 450 mg of THC (from 5 grams of 10% THC flower) × 0.6 (60% extraction) = 270 mg of THC
• 675 mg × 0.6 = 405 mg of THC
• 900 mg × 0.6 = 540 mg of THC

How much THC is in each edible?

Once you know how much THC is in your fat (butter or oil), you can easily work out how much ends up in each edible, assuming it's evenly mixed.

Common THC doses:

• 2.5 mg
• 5 mg
• 10 mg

Dividing the total THC to get the dose per edible:

• 270 mg of THC (5 grams of 10% THC flower):
  • 270 mg / 2.5 mg = 108 servings
  • 270 mg / 5 mg = 54 servings
  • 270 mg / 10 mg = 27 servings

For 20% THC flower (540 mg of THC):

• 540 mg / 2.5 mg = 216 servings
• 540 mg / 5 mg = 108 servings
• 540 mg / 10 mg = 54 servings

Other things to keep in mind with THC edibles

An edible's potency isn't the only thing that shapes the high. When you work out a dose, you also have to factor in the person taking it. Here are the key things to consider:

THC tolerance

THC tolerance generally carries over between smoked cannabis and edibles. If you smoke regularly, you probably have a higher tolerance. Even so, don't go overboard with edibles, because their effects last longer and hit harder.

Body weight

Body weight plays a big role in edible dosing. Heavier people generally need higher doses to feel the effects, while lighter people should start smaller. It's always best to start low and go slow, especially if you're on the smaller side.

Mood

Your emotional state can shape how you experience THC. If you're feeling nervous or unsure about taking edibles, wait until you're more relaxed and confident. A positive, calm headspace can make a big difference.

Expectations

Be clear about the kind of experience you're after. If you just want to unwind and have a good time, start with a low dose. If you're going for a stronger high, you can adjust the dose accordingly, but always carefully. Remember, it's easier to take a little more than to deal with having taken too much THC.

Food intake

What you've eaten can affect how hard edibles hit. It's a good idea to eat a proper meal before taking edibles, since a full stomach can slightly soften the high. Taking edibles on an empty stomach can make the effect come on faster and stronger, which isn't what everyone wants.