Ask Cheri

How to Calculate THC Percentage in Cannabis 

By Cheri Sicard
October 14, 2020

Dear Cheri,

How do I calculate the THC percentage in my weed?  Estimating the THC percentage is the hardest part of figuring out proper dosing for me.

I made some weed butter using your dosing calculator and I took your advice and estimated a percentage, but it was more potent than I guessed.  I don't live in a state that is regulated so I have no idea what it is or what to do.

No worries.  It is possible to calculate THC percentage in cannabis, even if you don't have a lab test.  But it might take a little practice.

If you don’t have regulated cannabis that comes with lab test results, or you don’t have access to a testing lab, and most home consumers don’t, you will have to do your best to estimate the THC percentage.

In my free (and paid) dosing classes, I give you typical ranges for THC to help you estimate.  I talk about everything from schwag or low quality brick weed all the way up to top shelf.  Your job is to figure out where the material you are cooking with falls into those ranges.

I know you have taken the class and are still having problems.  Stick with it, it will get better, I promise.

In my opinion, the best way to start to learn how to estimate THC percentage in cannabis is to smoke or vape a little to get an instant idea of how strong it is.  Then make an educated guess as to where your material fits into the categories in the dosing class.

I know it is not exact but with more experience you will get better at it, trust me.

You already have some experience from this time that you were estimating too low.

Each time you do it will you learn something new and you will get better at the process until accurately estimating THC become percentages will become second nature.  

For real.  I get emails from students all the time in the same position as you, then follow up emails a month or so later thanking me for getting them through the discovery process.

To be sure, discovering your optimal cannabis dose can take time but it is sooooooooo worth it.  Once you have that dialed in, you can always create edibles that are exactly what you need.

Otherwise the only way to calculate THC percentage is to lab test it.  That is usually not practical nor affordable for home consumers, at least not at this point in our history.  

Also note that when it comes to CBD percentages, a lab test is the only way. Estimating CBD percentages is not reliably possible.

Help with answering the question of estimate THC percentage in cannabis - woman wondering and photo of cannabis cola.

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About the author

Cheri Sicard is the author of Mary Jane: The Complete Marijuana Handbook for Women, and The Easy Cannabis Cookbook.  Her online courses at have educated 1000s of students about marijuana, cannabis cooking for home cooks, and making infused topicals.

  • I would recommend trying a little bit of the finished butter on a cracker to sample the potency prior to making edibles with it. Then you could always thin it down if it’s too potent, or re-melt it if you want to make it stronger. Keep track of measurements for future reference.

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