THC Tests Are Often Wrong, Here’s Why
Photo credit: Julie Jacobson / AP
If you're hunting for the strongest herb with the highest THC content, you’re not alone. But have you ever wondered if those numbers on your cannabis packaging are really accurate? I used to trust them completely, but once I learned how THC testing actually works, my perspective changed. And after you see what really goes down behind the scenes, you might change your mind too.
Why THC Matters
We all know THC isn’t everything when it comes to picking a great strain, but it’s still an important factor. It’s a major indicator of a product’s potency and plays a big role in determining the price. THC testing is a cornerstone of the legal cannabis industry and is usually required for most legal products. At first glance, the process seems like a foolproof way to ensure accuracy—but as you’ll soon see, that’s not always the case.
A Shocking Study
One of the clearest examples of THC testing issues comes from a 2023 study called “Uncomfortably High: Testing Reveals Inflated THC Potency on Retail Cannabis Labels.” This study examined 23 cannabis samples from 12 strains across 10 dispensaries in Colorado, testing the actual THC levels compared to what was advertised on the packaging.
The results? Not good. On average, the real THC levels were 23.1% lower than the lowest reported values and 35.6% lower than the highest reported values. Even more shocking, 57% of the samples had THC levels that were over 30% lower than what was listed on the label. One sample had a whopping 34% lower THC content than advertised.
The study didn’t identify the exact cause of these discrepancies, but it highlighted four likely factors:
Different testing methods used at various labs.
Sample degradation over time (especially if the product has been sitting on the shelf).
Sample collection bias, where only the best buds are chosen for testing.
Economic incentive, with companies benefitting financially from higher THC results.
These results raise serious concerns about how accurate THC labels really are—and this isn’t the only study that’s shown similar issues.
The THC Testing Process
In most U.S. legal markets, THC is tested using High-Performance Liquid Chromatography (HPLC). This method is effective for measuring THC, other cannabinoids, terpenes, contaminants, and more. Here’s how it works:
Sample Collection: This is where things start, and it's also where problems can occur. As someone who’s worked as a grower, I’ve done this myself. When you test a batch of flower, you don’t send in all the plants—you only submit a few grams from the harvest. Maybe a quarter ounce from hundreds of plants.
The goal is to take samples that represent the entire crop, but there’s no strict oversight to ensure this is done fairly. In many cases, growers can just pick the best-looking buds from the top of the plant, where THC levels are often higher.
This means the test sample might not reflect the overall quality of the entire harvest, giving a skewed result.
Lab Preparation: Once the sample arrives at the lab, it’s registered, labeled, and prepped for testing. The bud is ground into a fine powder, and a small portion is dissolved in a solvent like acetonitrile to create a liquid solution.
Chromatographic Separation: This part can sound complicated, but it’s pretty simple. The liquid solution is injected into a tiny tube, where different compounds in the cannabis stick to particles inside. Some compounds stick for longer than others, which allows the lab to identify and measure each one.
The machine detects the THC and other cannabinoids, giving the final report that determines the THC percentage printed on your product label.
When done right, this process is accurate. But, as the study showed, things often don’t go as planned.
HPLC Testing
This testing is very accurate, but only if it’s done right.
When greed comes into play, anything goes.
Collection Problems: Why Your Sample Might Be Misleading
One of the biggest issues with THC testing comes down to how the samples are collected. As I mentioned earlier, growers don’t send in all their plants for testing. Instead, they pick a small sample that’s supposed to represent the entire batch. But in reality, there’s nothing stopping them from choosing only the best buds—the ones with the most trichomes and highest THC content.
Since most growers only need to send in a few grams for testing, this small sample might not reflect the quality or THC levels of the entire harvest. This creates an opportunity for companies to game the system by submitting their best-looking buds, which results in higher THC numbers on the final report—numbers that may not represent what you’re actually buying.
The Money Problem: Economic Incentives to Cheat
One of the most significant factors in THC inflation is the economic incentive (big surprise). Cannabis products with higher THC percentages sell for more money, so there’s a strong motivation for companies to get the best possible test results. This can lead to growers selecting ideal samples, "lab shopping" (choosing labs known for giving favorable results), or even paying extra for a THC boost on the report.
This issue has been seen across the cannabis industry, with some labs being suspended for unethical practices. A study of the Nevada and Washington cannabis markets found that many products tested just over 20% THC—a suspiciously high number that seemed too consistent to be natural. This practice, called "bunching," indicates something fishy, like companies pushing for specific results to boost sales.
Cannabis brands were able to pay these testing labs to get better results, but all the test results were almost the same - so they eventually got busted.
Why This Matters
The truth is, THC testing isn’t as reliable as we’d like to think. Whether it’s growers hand-picking the best buds for testing or labs being incentivized to provide favorable results, the numbers on your product label might not reflect the actual potency. The next time you see a strain boasting 30% THC, remember—it might not be what you’re actually getting.
Understanding how THC testing works (and where it can go wrong) can help you make more informed choices when buying cannabis. So, while THC numbers matter, it’s always a good idea to focus on the overall experience rather than just chasing the highest THC percentages.
Watch me talk about this more on my youtube video below. Bongs Up!
