Calculate THC Potency

December 4, 2025

Why Calculating THC Potency Matters

When you make edibles at home — using cannabutter, oils, tinctures, or other infused products — the final effect depends heavily on how much THC (or other cannabinoids) actually gets infused and consumed. Without calculating potency:

  • You might end up with much stronger edibles than intended — increasing risk of unpleasant side-effects (over-intoxication, anxiety, etc.). Leafly Weedmaps+2NuggMD+2

  • Or your edibles might be so weak they have little to no effect, wasting time, material, and effort.

  • Consistent dosing and safety are hard, especially when sharing with others.

By doing a potency calculation, you can roughly estimate mg THC per serving — which helps you dose responsibly and avoid surprises.

Key Concepts & Variables in Potency Calculation

To estimate THC potency in homemade edibles, you need to start by knowing or estimating:

  • Amount of cannabis (flower or concentrate) used (in grams or other units).

  • THC percentage (potency) of that source (e.g. 15 %, 20 %, etc.). This is often provided on packaging or a lab certificate. Aloha Green Apothecary+2GreenDoor SF+2

  • Losses due to decarboxylation and infusion — heat, extraction inefficiency and processing reduce the theoretical maximum THC that ends up in your butter/oil/tincture. Common working assumptions are ~ 80% of THC carries through. Veriheal+2Chronic Bakes+2

  • How much of the infused fat (butter/oil) you actually use in the recipe (you might not use the entire batch). Veriheal+1

  • Number of servings (pieces) in your final recipe (e.g. cookies, brownies, slices) — to divide the total THC by the number of servings. Grow Cannabis School+2GreenDoor SF+2

Step-by-Step: How to Estimate THC per Serving

Here’s a commonly used formula/workflow for estimating THC potency — though keep in mind it’s approximate, not exact.

1. Calculate theoretical total THC in your starting cannabis

  1. Convert grams of cannabis to milligrams:

  2. Multiply by THC% (as a decimal) to get potential THC.

    • Example: 7 g cannabis at 20% THC → 7 × 1000 × 0.20 = 1,400 mg THC total (in theory) before losses.

2. Adjust for decarboxylation & infusion losses

Because decarboxylation (activating THC) and infusion (transferring THC from plant into butter/oil) are imperfect, not all of that potential THC will make it into your final infusion. A common conservative assumption: about 80% of potential THC remains available. Veriheal+2Chronic Bakes+2

  • Using the example above: 1,400 mg × 0.80 = ~1,120 mg THC in your full batch of infused fat/butter/oil.

Some resources use slightly different efficiency assumptions (60–85 %) depending on method and fat/oil used. Chronic Bakes+2Sativa University+2

3. Determine how much infused fat you use in the recipe

If you made, say, 1 cup of cannabutter but only use ½ cup in a recipe, then you are only using half the THC.