What is the best cannabis potency calculator?
For most people, the best cannabis potency calculator is a free edible dose calculator that runs the THCA to THC conversion, multiplies total THC by the weight of cannabis used, and divides the result by servings. It answers the only question that matters: how many milligrams of THC sit in one bite, one capsule, or one dropper.
Does Higher THC Mean Stronger Effects? A Practical Guide
If you cook edibles a few times a year, a browser based dose calculator wins on speed. If you infuse butter, oil, or tincture in batches, pick a calculator built for infusions instead.
more on this topic
How we ranked the options
Every calculator on this list had to do three things: accept a labeled THC percentage or a THCA value, apply standard decarboxylation math, and show a clear milligram per serving result.
Cannabis Potency Testing Kits: Home Users' Guide
- Accuracy of the total THC formula
- Clear per serving output
- Support for flower, concentrate, and infused fat
- No signup or payment gate
Top cannabis potency calculators compared
1. Edible dose calculators from menu platforms
Leafly and Weedmaps both publish free dose calculators that convert a labeled potency into milligrams per serving. They win for beginners because the output is a number, not a formula. The limit is batch work: neither scales a full tray of brownies or a jar of oil.
2. Infusion calculators for butter, oil, and tincture
Infusion tools ask for the weight of decarbed flower, the fat or solvent volume, and the recipe's serving count. They estimate extraction loss, often 10% to 25%, so the final number lands closer to reality. Accuracy still depends on how well you strained the batch.
3. THCA conversion calculators for raw flower
These tools read a certificate of analysis and return total THC for the strain. They suit shoppers who want to compare a 22% THCA label against a 20% THC label on equal footing. You need a real lab number to get a useful answer.
4. Spreadsheet templates
A homemade sheet gives full control over serving size, extraction loss, and cost per milligram. It also saves your past batches for repeat runs. The downside is manual entry, and a single typo skews every result after it.
What math does a cannabis potency calculator run?
Total THC follows a fixed formula used by testing labs: total THC = (THCA x 0.877) + delta-9 THC. The 0.877 factor accounts for the mass lost when the acid group leaves THCA during decarboxylation.
- Convert THCA to THC with the 0.877 factor.
- Multiply potency by cannabis weight in milligrams. One gram of 20% THC flower holds roughly 200 mg of THC.
- Subtract extraction loss, then divide by servings.
What inputs do you need?
- Weight of cannabis used, in grams or ounces
- THC and THCA percentages from a lab label
- Volume of butter, oil, or tincture in the recipe
- Number of servings the recipe yields
How many mg of THC is one dose?
Most states cap a single edible serving at 10 mg of THC, and 5 mg is the standard commercial serving. Beginners usually start at 1 mg to 2.5 mg and wait two hours before a second dose.
Frequently asked questions
Are cannabis potency calculators accurate?
They are as accurate as your input. Potency shifts from bud to bud, and home extraction rarely pulls every milligram, so treat the result as a ceiling rather than an exact figure. Lab testing your own infusion is the only way to confirm.
Can a potency calculator convert THCA to THC without heat?
No. The 0.877 factor is math alone. THCA still needs heat, about 220F to 240F for 30 to 60 minutes, before it becomes psychoactive THC.
Does the calculator work for vape carts and concentrates?
Yes, if the label lists THC and THCA. Activated concentrates skip the decarboxylation step, so enter the total THC value directly.
Bottom line
Start with a free edible dose calculator that shows milligrams per serving and runs the THCA to THC conversion. Move to an infusion calculator once you work in batches of butter, oil, or tincture.