Interactive calculator

THCA to THC conversion calculator

Estimate potential THC after decarboxylation using the standard educational conversion factor of 0.877.

THCA percentage Enter the THCA line from the product COA. Do not use total cannabinoids or marketing potency. Product weight (grams) Use the amount of flower or product you want to evaluate, not necessarily the full package.

How to read the estimate

From COA percentage to theoretical THC

The calculator is most useful when it helps you compare labels carefully, not when it promises an exact experienced dose.

Step 1Find THCA on the COA

Use the raw THCA percentage from the cannabinoid panel, not marketing copy.

Step 2Apply the conversion factor

Multiply THCA by 0.877 to estimate the theoretical THC after decarboxylation.

Step 3Multiply by product weight

Use the grams you plan to evaluate, then convert grams to milligrams.

Step 4Account for real-world loss

The final experienced amount is usually lower than the theoretical maximum.

Recommended next steps

Use conversion context before comparing THCA products

Potency is only one part of a better purchase decision. Vendor transparency, COAs, legality, and format matter too.

ProductsBrowse THCA FlowerCompare flower options with potency, product type, and vendor context.GuideIs THCA Legal?Review legality and compliance context before comparing products.ToolTHC Dosage CalculatorUse a conservative dose planning tool for edible or tincture formats.ToolTolerance EstimatorCheck whether recent use changes how strong THCA products may feel.

Format context

Compare THCA products with more than a potency number

Theoretical THC can help decode labels, but product type and testing transparency decide whether the recommendation feels trustworthy.

FlowerTHCA flowerCompare strains, pre-rolls, snow caps, and vendor documentation.GuideTHCA overviewUse the editorial guide before interpreting product claims.Legal contextIs THCA legal?Review why state rules and testing matter before buying.ToleranceEstimate sensitivityUse recent consumption patterns to plan more conservatively.

What is THCA?

THCA (tetrahydrocannabinolic acid) is the raw, non-intoxicating form of THC found in fresh and dried hemp flower. It does not produce psychoactive effects on its own. When heated — through smoking, vaping, or cooking — THCA undergoes decarboxylation and converts into delta-9 THC, which is the active compound responsible for the effects most people associate with cannabis.

Where does 0.877 come from?

The 0.877 conversion factor comes from the molecular weight difference between THCA and THC. THCA has a molecular weight of 358.5 g/mol. When it loses a carboxyl group (CO₂) during decarboxylation, it becomes THC at 314.5 g/mol. Dividing 314.5 by 358.5 gives approximately 0.877 — meaning roughly 87.7% of the THCA by weight converts to THC under ideal conditions.

How to find THCA % on a COA

A Certificate of Analysis (COA) from an accredited lab will list THCA as a percentage of the total sample weight. Look for a line labeled "THCA" in the cannabinoid panel — not "Total THC," which is a calculated figure. The raw THCA percentage is what you enter into this calculator. Many reputable vendors publish current COAs on their product pages or provide a QR code on the packaging, but you should verify that documentation yourself.

Real-world limitations

This calculator assumes complete, ideal decarboxylation. In practice, conversion is never 100% efficient. Combustion (smoking) typically converts 60–80% of available THCA. Vaping varies by temperature — lower temps preserve terpenes but convert less THCA. Cooking or baking at controlled temperatures can approach the theoretical maximum but still varies by time, heat distribution, and fat content. Use this estimate as an educational reference, not a precise dosing tool.