How Health Canada interpret the unit "mg/unit"?

Hello everyone, I’m new to this forum and the cannabis industry. I’m working on something related to the potency of edibles, and I’ve encountered an issue with the way my company calculates potency.

We receive potency results from a third-party lab in milligrams per gram (mg/g), which we then need to convert into milligrams per unit (mg/unit). However, I’ve noticed that my company uses the declared weight of the product instead of the unit weight when calculating potency. As a chemist, this seems strange to me. In my experience, we calculate concentration by knowing the exact volume of a liquid. So, I believe that the potency calculation should take into account the actual weight of the sample, which may differ from the declared weight, to accurately determine the amount of cannabinoids inside each unit of edible.

I’m wondering if I’m correct in thinking this way, or if Health Canada actually considers mg/unit to be equivalent to mg/declared weight. Any insights or guidance would be much appreciated. Thank you!


Why is this in quotes?

to make it easier to read

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the concentration is a representation of the whole lot, and there is a tolerance on potency and on weight so those are your controls

I believe there is a +/- 10% variance allowed on unit weights, depending on your unit size. So if your declared weight is 1g, and your unit weight is within 0.9g-1.1g, you are fine using the declared weight.

It’s also entirely possible that whoever at your org chose the process for doing the math in the first place is doing the math wrong. It happens a lot in this industry. HC doesn’t tend to notice stuff like that until it’s pointed out to them.


While my org permits edibles that weigh equal or more than what’s declared, there is no specified maximum weight allowed. Furthermore, the average weight of the products seems to be increasing. While I agree that the potency difference is still acceptable, I have concerns about the potential issues that could arise with the weight if we continue this practice…

If your organization is having formulation changes then those would need to be reported, stability reconfirmed, and process method revalidated. That’s just the rules.

As @Lincoln20XX said - there are tolerance limits, your company defines what those are, as long as they are within the legal limits set by HC.

You could be pushing higher, this happens often due to environmental changes without intentionally changing the formulation. What you are describing doesn’t really sound like that though.

Do you know why the average weight is changing? Is it changing more than the formulation defined percentage? That percentage of tolerance should be on your batch record and part of your quality control review process. Someone should be checking them every so often just to make sure all is correct.

Its possible that your quality control department knows this is an issue and is already investigating it and working on a corrective action. This kind of stuff happens.

If you don’t have a QC department, then it will be much harder to meet HCs demands. I’m pretty sure they actually require you have one. Sometimes people have them, but don’t really fund them so its hard for them to do their work.

In any case - when you submit your product for consideration that includes the formulation, which includes all ingredients, quantities, unit weights, tolerances, and dosing information. This gets approved. Its a pretty simple process.

As chemists its totally normal for us to feel weird when things are kind of back of the napkin mathematics. Just try to remember that is how it is for ALL FOODS and most DRUGS. Tolerances for all ingredients, averages instead of actuals.

I don’t know which lab you are using (are you doing the testing yourself?) – in all of my labs we ask that we get enough units to do a 10 piece average weight. If the RSD across those is less than 2% then we call it “good” and move forward with the average weight of those items. In some labs, we let this number remain consistent across many months of testing - unless there is a laboratory investigation.

Sadly - many states (although I don’t think HC…) don’t require that you submit enough “samples” for you to really get a good representative sample. That means that these numbers are all bogus most the time anyway. And with limited process validation - you could be pushing out all kinds of stuff.

This has always made me uncomfortable as well - because I come from pharma under the FDA where the regulations require that you CARE about these things and MONITOR/CONTROL for them.

Food is just not the same and most states and HC seems to lean towards treating cannabis products like food and not like dietary supplements or drugs.

Such is life. Feel free to reach out if you want to talk about it a bit more. There are methods to do some more checks, and it may not be nearly as bad as it seems.

Oh and remember - you may be thinking that a calculated potency of a dosage form is inappropriate because it feels like it has too much error built, but there is always uncertainty - and how much we are willing to accept is all up to our risk tolerance. And most people think the risk with cannabis products is pretty low (its not like hormones… or opiates… where dosage shifts will kill you…) so perhaps you can take a nice exhale knowing that even if there is something wrong with the math, it probably isn’t so wrong that it will kill someone, but instead just get you in trouble with the regulators if they decide to look at it, which they probably won’t. <3 -hugs from Michigan, which I’m told is basically Canada-


Correct. HC doesn’t really (presently) care about that. Many companies get by with a single COA. Here is the Health Canada New Product Notification publication laying out what they look for when submitting new products. The whole process is incredibly hand-wavey.

Many companies we talk to don’t know what a representative sample is, or how to collect one.

We just went through a long exercise of re-building our sampling and testing protocol to minimize any measurement error introduced by our instruments. We do everything by mass, not by volume, and we’ve included temperature-based density compensation and tried to ensure that any measurements we are making keep the potential introduced instrument error to 0.1% or below.

It doesn’t eliminate uncertainty or the possibility of error, but the more things you control, the more confidence you can have when you get results that don’t make sense.

If anyone needs a recommendation to a very competent west coast Canadian analytical lab that is capable of repeatable high precision analysis and doesn’t blink when you ask for odd or custom testing protocols, please DM me. They are presently the only lab that I would recommend for extractors or cultivators in Canada. I don’t have any experience on the edibles side of things, but I have reason to believe that they would be very competent in that area.


Hello, Cassin. I work in the R&D department and must adjust the use of cannabinoids in response to a request from the QA department if the potency of the products is not satisfactory. The increase in average weight is intentionally allowed by the QA department to ensure that the potency of the product is always equal to or higher than the declared potency, but not more than 15% of it. I completely understand that our industry is more concerned with the range than with the specific potency for each sample. I just have a feeling… I’m not sure if we really need to increase the cannabinoid amount or how much extra we have to add when the qa make such request. I just don’t want it to be added arbitrarily. In fact, I convert mg/g to mg/unit using the average unit weight. This could boost my confidence in making the decision. However, the QA department never accepts my interpretation of the potency data and instead demands that I follow their orders. This saddens me.

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I am with you, but also, welcome to the federal Canadian Cannabis game, shit saddens us all.