How Many Grams in An Ounce? – Measuring Weed

ziplock bag of an ounce of marijuana
Michael Moloney/

We get it. With all the excitement about marijuana legalization, sometimes a reminder of the basics is just what’s needed. In this guide, we will look at how many grams are in an ounce, along with numerous other measurement conversions perfect for the cannabis consumer.

No matter where you learn them, weight conversions are useful beyond the specific reason you were taught. As the cannabis industry continues to expand across the US, it is becoming more and more necessary for consumers to be educated not only in the product they intend to use but the way the effects and potency are measured

Measurement Conversions Show Broad Information

I recently had a conversation with my father. He is aware (though wary) of the industry I work in and write for. During our conversation, in preparation for this piece or just out of some impulse, I asked if he knew how many grams were in an ounce. Without skipping a beat, he relayed the measurement conversion, later citing the cereal boxes he'd read over at breakfast as a child.

True, in the cannabis industry as much as with any other consumer market (from medicine to breakfast cereal), having an understanding of conversions between weight, volume, potency, and effect. Too much cereal may cause nausea. Too much weed, and paranoia or red eyes may appear. Without an understanding of each consumer item individually, general risk finds a sturdier footing around all of them.
For instance, if asked how many grams in an ounce, a well-rounded response is based on three things:

  • The weight of the ounce in grams (clearly) 
  • The potency of THC and other cannabinoids in a strain by percentage (total THC volume) 
  • The volume of cannabinoids needed to cause the desired effects (potency by weight) 

This requires a thorough understanding of how weight is defined between measurement systems, including the imperial, avoirdupois, household, and metric systems.

Don't worry; many of these conversions require simple math and can be done readily by a calculator.

Let's start by first listing several of the most common conversions needed for marijuana, starting with how many grams are in an ounce and working backward.

Common Flower & Concentrate Measurements

The following measurements are commonly used in the cannabis industry. While used predominantly in measuring flower and concentrates, they are used across the industry for various products.

    1 gram =  1,000 milligrams
  • Example: 3 grams of concentrate x 1000 mg = 3000 mg of concentrate
1 kilogram = 1,000 grams 
  • Example: 500 grams of flower / 1 kilogram = 0.5 kilograms
1 kilogram = 2.2 pounds
  • Example: 1 pound of trim / 2.2 pounds per kilogram = 0.45 kilograms = 450 grams
1 pound = 16 ounces
  • Example: 1/4 pound of fresh nugs / 16 ounces per lb = 4 ounces of nugs
1 ounce = 28 grams
  • Example: 2 ounces of shatter = 28 grams in an ounce x 2 = 56 grams of shatter
1 pound = 454 grams 
  • Example: 454 grams per lb / 0.25 lb of flower = 113.5 grams of flower

Edible & Oil Measurements

Household and avoirdupois measurements are common and easily recognizable, even if it’s unclear how they convert for the cannabis user or what they mean in general. Just as the measurements listed above illuminate how many grams are in an ounce, the following measurements can help explain how many milligrams are in each dose (useful when making edibles or using oils), along with other helpful cannabis measurement tips.

1 liter = 1,000 milliliters (ml)
  • Example: 500 ml CBD-infused water = ˝ liter of CBD water
1 teaspoon (tsp) = 5 ml
  • Example: 1 tsp of cannabis tincture x 5 ml per tsp = 5 ml of cannabis tincture
1 tablespoon (Tbsp) = 15 ml 
  • Example: 3 tsp (5 ml x 3) of CBD oil = 1 Tbsp = 15 ml of CBD oil
1 fluid ounce (fl oz) = 30 ml 
  • Example: 8 oz of cannabis-infused drink x 30 ml per oz = 240 ml
1 cup = 8 fl oz 
  • Example: 2 cups of cannabis oil x 8 fl oz per cup = 16 fl oz of oil
1 pint = 473 ml 
  • Example: 16 fl oz of cannabis-infused butter x 30 ml per fl oz = 1 pint of butter

Percentages & Ratios Used in Measuring Cannabis

The potency of individual cannabis products varies greatly. The number of grams in an ounce makes no difference if each gram lacks potency, therefore producing little beneficial or intoxicating effect. The potency of cannabis products is commonly measured in two ways:

  • By potency strength 
  • By a percentage of the weight 

Edibles are commonly measured in milligrams. Potency percentages are common among products like oils, concentrates, and flower, all tested in the lab for cannabinoids BY WEIGHT and not milligram. The percentage by weight of active cannabinoids can, however, be expressed in milligrams using the following simple conversion rule:

Each percentage point is equivalent to ten times itself in milligrams. Remember, each gram is equal to 1,000 milligrams 

Here are some examples: 

A gram of cannabis concentrate testing at 75% THC 
  • 75% THC x 1,000 mg per gram
    • 750 mg THC per gram of concentrate
An ounce of flower grown outdoors testing at 10% CBD and 4% THC 
  • (10% CBD x 1,000 mg per gram) + (4% THC x 1,000 mg per gram)
    • 100 mg CBD and 40 mg THC per gram

Marijuana Measurements: Bringing It All Together

Grams of Marijuana
Photo by: Michael Buffalo / Shutterstock
Using the conversions above, we should now be able to easily and readily identify a number of common measurements used by the cannabis industry, as well as reason through and understand how to dose edibles and other products. Check it out:

How many grams in a 1/8th? 

For numerous medical and recreational cannabis consumers, buying in bulk doesn’t fit their consumption frequency or medical treatment plan. Often, such individuals will limit their purchases as a result. The most common measurement outside of grams in an ounce is grams in an 1/8th.

Recall from above, an ounce is equal to 28 grams. 1/8th of cannabis refers to the resulting weight if you divide 28 grams into eight equal pieces. Such an action defines each 1/8th of an ounce as equivalent to 3.5 grams.

How many grams in a quarter ounce?

Referred to by many as simply a "quarter," a quarter-ounce represents 25% of an ounce.

28 grams per ounce x 0.25 ounce per quarter = 7 grams per quarter ounce

How many grams in a half ounce?

Following our conversions for grams in an ounce helps us easily determine how many grams are in a half ounce as well.

28 grams per ounce x 0.5 ounces = 14 grams per half ounce

How many grams in an ounce?>

There are 28 grams in an ounce.

How many ounces in a quarter pound? 

Fluid ounces convert to metric measurements different from those used when converting solid ounces. When measuring a solid substance such as flower or concentrate, one pound is equal to 16 ounces of product.

16 ounces x 0.25 pound = 4 ounces per quarter pound

How much THC per milliliter is available in a 2 fl oz tincture with 300 mg THC per bottle? 

For this, we need to know how many milliliters (ml) are in each fl oz of the cannabis tincture. Pulling from the conversion chart, each fl oz is equal to 30 ml. We get:

  • 30 ml x 2 fl oz = 60 ml per 2 fl oz
  • 300 mg THC / 60 ml per bottle = 5 mg per ml
Testing at 15% THC, how many grams of an ounce are needed to have 600 mg of THC? 

Say you are making edibles and need to figure out the amount of cannabis to adequately dose each. You'd like to make a 600 mg batch, divided into 60 doses of 10 mg each.

  • 15% of 1,000 mg is equal to 150 mg THC per gram
    • 600 mg THC / 150 mg per gram
      • 4 grams of flower per 600 mg of THC


As you can see, the cannabis industry in the US has embraced several measurement systems, creating a web of mixed measurements sometimes difficult to easily recall. From how many grams in an ounce to how many milligrams per dose, we hope this guide gives you the tools necessary to navigate the wonderful world of cannabis with an (ahem) measured confidence.