Product Review: tCheck Cannabis Oil Potency Tester

tCheck Cannabis Oil Potency Tester Copyright

We have been making our own infused butter and oils – and teaching other people how to make, use, and dose themselves – for well over six years now. We’ve even come up with a formula to calculate how much THC is theoretically in your homemade oil, but there’s never been a reasonably affordable way to actually measure it. Commercial cannabis labs are super accurate, but cost somewhere between $50 and $100 to test a single sample. So now along comes tCheck, with a nice little game changing wizardly product the size of an older iPod, for just $299.99 with no consumables or anything else to buy.

The technology behind tCheck is deceptively simple. Using a spectrometer, it was determined that all cannabinoids have a secondary peak wavelength at 320 nm, so they designed their photosensitive detection using an LED that emits light at the proper frequency, shines through the oil, and the result gets turned into an exact measurement.

One limitation of tCheck is that it cannot tell you all the separate cannabinoids that are in your sample, only the total cannabinoids by volume (CBV, expressed as milligrams per milliliter). Yet that’s still plenty of important information, especially since most users will know precisely what they started with. Your dispensary already tells you how much THC and CBD is in your bud or concentrate, and their exact proportions, but only the tCheck can tell you how much of that actually made it into your oil.

If you’re not in a “legal area”, the tCheck might even be more valuable. You’re probably only getting THC in your bud anyway, so you really have little or no idea how strong your finished product is going to be…unless you use tCheck. We’ve already warned people what can happen if they eat too much THC in their edibles! And if you are trying out some of the “legal CBD” products (some of which are several hundred dollars per bottle), tCheck could help verify that you’re actually getting the CBD you’re paying for.

Checking Out tCheck

Unlike many high tech and cannabis startups, the people at tCheck seem to be immune to hype and wild claims about their product. For instance, they mention that their battery will last for “more than 50 tests per full charge”, though our own testing shows that 40 consecutive tests drop the battery level only 24%…which means their product claim is much more conservative than actual results.

Tcheck supplied me with a unit for review, and we’ve been working with it for several weeks now. The first thing I did was carefully attempt to load infused oil into the test chamber, using the supplied test slide and precut filter paper. Half an hour later, I realized that the filters were actually removing the oil from the test chamber by capillary action, and stopped using them. Immediately after that, I started getting valid results. tCheck has subsequently come to the same conclusion: the filters are useless, and everything works just fine without them.

The company seems quite responsive. When the unit first arrived, we noted a number of minor bugs that were fixed within days and delivered as firmware updates over WiFi.

User Friendly

It’s really simple to use the tCheck. Mine arrived partially charged and already displaying the correct date and time, so all I had to do (just once) was input the login credentials for my WiFi network on the touchscreen. The company stresses that absolutely no information is “sent back” to them via the Internet, even the name of your WiFi connection, by the way. According to a company spokesperson, “If that ever changes, we will definitely have a notification to the user and have the option to disable that function. We are VERY big on transparency and we are not interested in data farming.”

Setting up WiFi allows the tCheck to “phone home” for firmware updates, so I got into the habit of checking for them every time I used it, though you certainly don’t have to. Likewise, you must calibrate the unit before you use it (which consists of pushing the calibration button), but you don’t really have to do that every time either, because it analyzes the exact characteristics of your particular unit.

To actually perform a test, you put just two drops of test liquid into the well on the concave half of the plastic test slide (almost exactly like a microscope slide), fit the corresponding convex half on top, push the slide into the tCheck unit, and push the “Run A Test” button. The unit thinks about it for a minute, and then tells you the result as milligrams per milliliter. This is a lot more useful than a simple percentage, because it lets you calculate the actual dosage directly. For example, a #00 capsule holds just under 1 ml of liquid, a tablespoon is 15 ml, etc.

Trust, But Verify

I first tested tCheck with plain uninfused olive oil and coconut oil, as well as salad dressing (checking for false positives!). They all came out with big fat zeroes, as expected.

Then I tested it with infused olive oil and six different “flavors” of infused canna-coconut oil. This is where it got interesting. I happen to have one particular mixture of oil we call API for All-Purpose Indica, that I made in my Magical Butter Machine by combining a number of strains, and it’s very strong. In fact, capsules made from this stuff are way too strong for me generally, although perfect for Felicity when she’s trying to go to sleep. So I carefully diluted a quantity of API for my own use, and labeled it “70% API”. When I tested the API, tCheck told me it was 8.3 mg/ml THC. Testing the “70% API” got a result of 5.9 mg/ml. Divide those numbers properly, and you get 71%. That’s what I call excellent consistency!

Also for testing purposes, I did repeat tests on a single sample of oil several times, sometimes leaving the slide in place and sometimes simply pulling it out and pushing it back in, without changing the test material. The results were either exactly the same or within tCheck’s published specifications (10% accuracy).

All the other oil tests also fit our experience with those oils in terms of their relative strength, other than a single sample. That one showed up as 1 mg/ml, even though it should have been over 4 times higher by calculation, and probably twice as much as that based on how strong it is when we take it. We’re still scratching our heads over that one, though tCheck verified that our unit was working fine.

Details and Future Plans

The product was formally developed by Engineered Medical Technologies. We spent a few hours recently with Peichen Chang, their CEO, and met most of their development and support team as well. Chang explained how their patented technology enables a reasonably priced, yet consistent and accurate product. The calibration process allows the precise characteristics of the UV-B LED and photoelectric detector to be analyzed before use, and then the 310 nm wavelength light shines through exactly 0.4 mm of oil. The plastic slide itself is made of a proprietary compound, and their software does the rest of the magic. They also showed us the collection of samples they had tested at Sequoia Labs by gas chromatograph to help them calibrate the tCheck units.

The people behind tCheck are medical marijuana advocates and patients, and as dedicated and focused on “doing it right” as anyone. They’ve cooked up coded an edibles calculator, and even a Chrome extension, to help you figure out the proper doses for your edibles.

“There’s really no other medicine we take where not knowing the amount is acceptable”
– Kelly K, tCheck Sales Chef

The tCheck will work with infused olive oil, coconut oil, ghee (clarified butter), and regular cannabutter (as long as you skim off the milk solids). They’re working on methods of testing vegetable glycerin and alcohol tinctures in the future, using the current hardware and free firmware updates. Chang told us that the tCheck should soon be able to test concentrates directly, by adding precise amounts of known solvents. Once this happens, home testing of home-pressed rosin will be a reality!

For the farther future, Chang sees a way to create a more expensive, but still relatively affordable model that will be able to analyze the exact proportions of THC and CBD. And they are planning to use their own product to help research the most efficient methods and temperatures to decarb and make infused oils, which is definitely something we support!

The Bottom Line

You will want a tCheck if you are a medical marijuana patient who is serious about knowing or tracking their dosage of homemade oil, butter, or edibles

You will want a tCheck if you are a medical marijuana patient who is serious about knowing or tracking their dosage of homemade oil, butter, or edibles, or someone who is informally making them for yourself or others (such as a caretaker or cannabis chef). Perhaps a responsible entrepreneurial type in a non-legal area might benefit from this, since licensed businesses in legal states must usually get their products tested by a third-party lab. Most fully legal oil, edible, or capsule manufacturers will probably want a tCheck around just for in-house sanity checking as well.

tCheck TC1S Oil Potency Tester, $299.99 with one year limited warranty

Old Hippie is a father of two boys and thankfully living in California where all this kind of thing is legal. He started smoking marijuana in 1967 in high school, experimented with mind-expanding drugs of all kinds, and then straightened out 15 or so years later to become an airplane pilot. After being diagnosed with depression in 2000, he lost his job and most of the following decade to prescription medications (such as antidepressants) which sapped his energy and will. Finally, a chance conversation with a friend led to a doctor’s recommendation for medical marijuana (MMJ). This changed his entire life, health, and outlook for the better. is his continuing story. It’s also his way to provide experienced advice on using medical marijuana effectively and responsibly, as well as advocacy, activism, and support for others. Old Hippie teaches about safe use of cannabis edibles, Canna Caps, vaporizers, dosing, and even microdosing.


Hello Old Hippie,

Any tips for a potion that will help me sleep (back pain) through the night without getting me high??

Jo Jo

For making oil, see this article. While there’s no specific “potion” for back pain, many people prefer high CBD indica strains for this condition, and if you use bud with a ratio of 8:1 CBD:THC or more, you are more likely to get relief without undue psychoactive effects.

With a small fortune invested in HPLC testing of infused oil samples through SCLabs on-hand, I was prepared to evaluate my tCheck device when it arrives. I eagerly looked forward to writing a shining review, backed with solid data, about this novel device that could perform economical home testing of infusions.

When the device arrived, I ran well over 60 tests as part of a Gage Reproducibility and Repeatability study. The results of the Gage R&R were about 30% of tolerance using an arbitrary, loosely set tolerance of ±0.5 mg/ml. The tCheck full scale range only goes up to 10.0 mg/ml so ±0.5 was very generous. A Gage R&R result of 30% would be just okay for a home tester I suppose, but not great. Industry standards for Gage R&R state that less than 10% is good; 10% to 30% needs work; over 30% is not acceptable.

However, the accuracy of the tCheck is not close to being acceptable. The best results were more than 400% lower than the HPLC test from SCLabs in Santa Cruz, CA which is not close by any stretch of the imagination. Someone could just guess at the value and be closer. I discussed the issue with tCheck over the phone and via email; they were very professional in how they handled my issue and went the extra mile to help me. I ended up sending my tCheck back twice and each time it came back “no-trouble-found”. I used unfiltered and then filtered coconut oil per their recommendation, coconut MCT oil, and Ghee butter, some of my oils were infused in the oven with no water used, others were infused in simmering water, and others in crockpots. Everything was strained through cheese cloth. The test results were similar for all samples; more than 400% low. For what it is worth, tCheck suggests the use of filtered coconut oils, coconut MCT oils (which freezes at an inconvenient 27°F), and Ghee butters; using these base materials reduces the number of particles that the light must shine through. When cooking healing salves or chocolate, and computing the dose using data from SCLabs, the effects were right on the mark compared to the effects of commercial products, which gives me even more confidence in the SCLabs test results over the tCheck results. By the way, SCLabs is in the processing of becoming ISO 17025 and ISO 170743 certified.

I REALLY did want to see this device perform well. I intended to verify the tCheck accuracy and Gage R&R and then be able to confidently test my products with the convenience, and lower cost that the system could have theoretically provided. Unfortunately, I have had to return my unit a third time, this time for a refund. My strategy must now revert back to doing larger batches and have the samples tested at SCLabs. If I learn tCheck somehow improved their device, I would like to try it out again. For now, this evaluation was costly to me and turned out to be a complete let down.

I am not familiar with this Gage R&R stuff, but you have brought up some interesting concerns. I intend to attempt to contact the tCheck folks again (they’ve been a bit hard to reach since January) to get their reaction. Thanks for your feedback!

The Gage R&R is statistical calculation based of many measurements of the same thing by different people. The results measure the variation in the measurement system arising from the measurement the tCheck device and the people taking the measurement. It is different than a “simple” accuracy level.

To contact them, I would suggest logging on to their site and starting with an email stating the issue and a phone number where you can be reached. If they can not answer you via email, they will probably give you a call. That has been my experience anyway. They do not publish a phone number for technical support that I am aware of.

tCheck will tell you their accuracy is right on based on repeated comparison tests from independent labs. However, there is a huge disconnect between the data they are collecting and my data.

I am not up on their technology 100% but I believe that they pass a UV light through the sample and make a determination of the levels based on the measurement of light spectrum and intensity that passes through the test sample. I would think a measurement like that would be very difficult to accomplish with the high level of variation in plant material, variation in impurities added to the base material, and individual infusion techniques.

I’m curious if anyone has received feedback based on similar results as KingKola1? King, I didn’t catch… did you have a final result of your Gage R&R? I also did some comparisons but not to the same volume. I tested 6 different coconut oil samples using TLC and came to a minimum of 400% lower… up to 700%. I can confirm the same scaling test that OldHippie conducted with the 70% deal, so I definitely feel the potential that they’re really close to cracking the case, but so far this product just isn’t there yet. I am giving them a bit to “troubleshoot” hoping it’s just my own device or someone forgot to carry the one… but I could get a lot more TLC testing done with that $300. 🙁

I just spoke to Kelly at tCheck and she says you can email her any time with questions at and also that a new software release is imminent, hopefully in the next week, that should deal with the fact that their supplier sent them a batch of LEDs with totally different characteristics which really screwed up their algorithms…

I recently received mine and I also calculated it was at least 400% off. Kelly told me about the update. She also said that kingkola1 gave them another chance and they sent a second unit. And presumably the performance is satisfactory? I was hoping kingkola could verify that. Appreciate any help.

Just received an email from Tcheck they are coming out with a new tester that requires an app and a smart phone (why not computer compatability via USB) plus subscription option for deeper testing of THC/CBD. To their credit they have been very nice to deal with and offer a 50% discount to Tcheck 1 owners. Their new model will be out the end of December and if you preorder they want a payment up front which is a fools errand too easy to get burnt……don’t ask how I know. I have done enough financing I will not pay to be on a wait list for what may be another version not ready for primetime.

When all is said and done we basically paid $299.00 to be beta testers for a product that was not at all ready for prime time which leaves me feeling a bit ripped-off. You have a great site here Old Hippie but I have to say maybe be you should be more cautious lending your credibility to extremely untested products. I think I’m done with Tcheck sadly a great idea very poorly thought out and executed.

I hear what you’re saying, but the repeatability and accuracy of the original tCheck has only gotten better through software updates. I do not know why they’ve gone to a subscription model after they made a point of “nothing else to buy” in their original unit, but I’d certainly expect to see proof that their new unit is actually better than the old one and that they can accurately show % constituents the way they claim before even thinking of “upgrading”.

I am really curious to hear if the latest version of the tCheck is more accurate. I sure would like to hear from KingKola1 again on the updated product. I can’t smoke anymore but wish to accurately dose myself during the day without qualms of over/under dosing! And since I grow my own, I definitely want to use my own product. Thanx for the help

The people at tCheck did a very professional job in finding the root cause and corrective action regarding my prior review. Sorry that this update is coming so late, but the software design changes and factory testing changes were a success. With the latest changes and updates received in 2017, my tcheck test results are now within 10% of laboratory tested samples which is excellent in my opinion considering there is variation in the sample being tested,etc. The latest revisions are sound.

Working the the tCheck people was very refreshing… How many products do you buy and find a problem with, just say return it, throw it out and buy a new one, etc.? These guys actually LISTEN to the customer and react in the best possible way as professionals – I don’t think I have ever really experienced service like that before. My hat is off to tCheck and I wish them the best of success with their new flower testing unit in 2018. They are amazing people and have a terrific product for home use.

Can this device help you optimize your decarb process? I have read elsewhere that it measures total cannabinoids. Doesn’t that mean it can’t tell THCA and CBN from THC?

Looks like the tcheck is a valuable tool. As soon as it can test concentrates directly, I must have one!

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