How many grams of THC is in a flower?

Quick Answer

The amount of THC in a cannabis flower can vary significantly depending on the strain, growing conditions, harvesting time, and curing process. Most commercial cannabis strains today contain around 15-25% THC by dry weight. Assuming an average flower contains around 20% THC, that equates to around 200 mg of THC per gram of dried flower material. So in one gram of average cannabis flower, you can expect around 200 mg of activated THC. However, THC levels can range anywhere from less than 1% to over 30% for extremely potent strains. The final activated THC content depends on the decarboxylation process which converts THCA to THC.

What affects THC levels in cannabis?

Many different factors influence the THC levels in cannabis flowers:


The strain genetics play a major role in determining the amount of THC the plant produces. Some strains naturally have very high THC levels, while others produce minimal amounts. Breeders selectively crossbreed plants over generations to develop strains with desired cannabinoid profiles.

Growing conditions

The environmental conditions in which cannabis is grown affects THC production. Factors like sunlight, temperature, soil quality, and nutrients impact THC levels. Stressors can sometimes spur plants to produce more THC as a defense mechanism. Optimal, controlled growing conditions usually produce the highest THC yields.

Harvesting time

Harvest time influences potency. THCA synthesizes over the flowering stage, peaking at maturity. Harvesting early produces lower THC flowers. Harvesting late allows more THCA conversion to occur, up to a certain point.

Curing process

Proper curing and drying after harvest preserves THCA and other cannabinoids. Overly fast drying can cause degradation. The curing process allows for continued metabolic activity and conversion of acids to active compounds.


Heating cannabis converts the non-psychoactive THCA into activated THC through decarboxylation. This reaction occurs naturally over time, but applying heat speeds the process. Cooking, vaping, smoking, etc. decarboxylate THCA into THC.

Average THC Percentages of Cannabis Strains

Here are some general THC percentages for different strain varieties:

Strain Type Average THC % Range
Landrace strains 2 – 5%
Ditch weed Less than 1%
Low THC hemp 0.3 – 1%
Mid-grade cannabis 10 – 15%
Top Shelf cannabis 15 – 25%
Exotic strains 25 – 30%+

As you can see, most high-quality cannabis flowers fall in the 15-25% THC range. Strains over 30% are considered extremely potent. On the other end, industrial hemp contains less than 0.3%. Over the years, selective breeding has increased average THC levels considerably.

Calculating Total THC Content

To calculate the total THC content:

1. Get a lab test determining the percentage of THCA and THC.

2. Add together the percentages of THCA and THC.

3. Multiply the total percentage by the dry weight of the flower.

For example:

A strain tests at 16% THCA and 0.5% THC.
Total THC% = 16% + 0.5% = 16.5%
If you have 1 gram of dried flower, multiply:
16.5% of 1 gram = 0.165 grams total THC

To convert to milligrams:
0.165 grams x 1000 mg/g = 165 mg THC per gram of flower

So for this 16.5% THC strain, smoking 1 gram would provide around 165 mg of available THC.

Decarboxylating THCA to THC

THCA in raw cannabis is non-psychoactive until it gets decarboxylated into THC. Decarboxylation removes the carboxyl group from THCA through heat exposure. This converts THCA into the psychoactive THC.

Full decarboxylation typically occurs between 220-235°F over 30-45 minutes. During this process, almost all of the available THCA gets converted into THC.

For example, if a strain has:

– 15% THCA
– 0.5% THC

Fully decarboxylating 1 gram of this flower will convert 150 mg of THCA into 126 mg THC (accounting for the loss of CO2 weight).

This brings the total THC to 126.5 mg in 1 gram of decarboxylated flower material.

Getting the Most THC from Your Flower

To maximize the available THC from cannabis flower:

– Choose a potent high-THC strain
– Ensure the crop gets properly flushed and cured
– Decarboxylate the dried flower prior to consumption
– Use methods like vaping that don’t combust excess material
– Grind the flower to increase surface area
– Vaporize around 390°F to efficiently extract THC/cannabinoids without overheating

Optimal decarboxylation and vaporization can make almost all of the THC accessible.

THC Dosage Guidelines

Always start low and go slow with cannabis, especially if you’re inexperienced. THC dosages affect everyone differently. These general guidelines provide approximate amounts for typical effects:

THC Dosage Effects
2.5 – 15 mg Mild relaxation
15 – 40 mg Moderate euphoria
40 – 60 mg Strong effects
60 – 100+ mg Very strong effects

Everyone has a unique tolerance, so start with 5-10mg to assess your sensitivity before increasing dosage. It’s better to take too little than too much when starting. When consuming edibles, wait at least 2 hours before taking more.

Avoiding Potential THC Side Effects

High THC doses can sometimes produce adverse reactions like:

– Paranoia
– Increased anxiety
– Rapid heart rate
– Short-term memory issues
– Lightheadedness
– Panic attacks

These side effects are usually only temporary but can feel unpleasant. Staying within your personal tolerance limits helps avoid negative THC experiences. Start low, go slow, and work your way up cautiously when trying new products or consuming after a tolerance break.

Using a THC Calculator

Online THC calculators are handy tools you can use to estimate dosages. Simply enter the product potency percentage and quantity to determine approximate THC levels.

For example, calculating a 100mg edible rated at 10% THC:

100 mg edible * 0.10 THC = 10mg THC total

This provides a rough estimate of THC content. However, it’s still best to start with a small amount to gauge effects before increasing dosage.


While THC content can vary widely across cannabis strains and products, a good rule of thumb is that high-quality cannabis flower may contain around 150-250 mg of activated THC per gram. Factors including strain genetics, growing conditions, harvesting time, curing, and decarboxylation all impact the available THC levels in the end product. Carefully controlling these variables can produce cannabis with exceptionally high THC concentrations upwards of 30%. However, starting low and gradually increasing dosage is advisable for inexperienced consumers to avoid potential adverse effects. Knowing the approximate THC levels in your cannabis helps determine optimal dosing.

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