What Does CFU Mean in Probiotics, Prebiotics, and Postbiotics?

Published on January 03, 2024

By Kristen Boye BS, Natural Health

Kristen Boye

Kristen Boye is a natural health expert, writer, copywriter, and editor. Kristen was raised on an organic farm in British Columbia which inspired her life’s work. She holds a Bachelor’s Degree in Natural Health, is a Certified Natural Foods Chef, co-owner of a medicinal herb farm, and is a natural foods and children’s health advocate. Kristen lives with her husband and two children on their medicinal herb farm in Western North Carolina.

Probiotics have recently become one of the most accepted and popular health trends.

From artisan cultured foods and kombucha to probiotic skincare and supplements, everyone is wild about the benefits of these friendly bacteria.

However, if you’ve ever looked at a yogurt or probiotic supplement bottle and wondered: “What does CFU mean?” this article is for you.

Here, we’ll discuss what CFU means in probiotic products and probiotic/prebiotic/postbiotics supplements, why it matters, and how other probiotic-related biotics are measured.

What Does CFU or CFUs Mean in Probiotic and Prebiotic Products & Supplements?

CFU stands for colony-forming units. A colony can refer to many things, but in this case, it is a group of bacteria that grow together.REF#3310

CFUs in probiotics refer to the number of friendly bacteria in that particular probiotic-containing product or supplement.

CFUs are measured by adding bacterial cultures to a special type of petri dish known as an agar plate. The cultures are often diluted to make them easier to count.REF#3311

The plate is then viewed under a microscope, and the number of visible colonies (CFU) present is multiplied by the dilution factor to provide the CFU/ml value. 

To put it simply, CFUs are a measurement of how many live active cultures are within a particular probiotic.

How are Prebiotics and Postbiotics Measured?

Most Probiotic supplements also contain Prebiotics and, in some cases, Postbiotics, which are measured differently.

Prebiotics are a type of fiber that resists digestion and ferments in the gut, where they provide food for probiotics.

Postbiotics are metabolic by-products of probiotic and prebiotic fermentation.

Both of these are more like food than bacteria and are therefore measured by weight in milligrams or grams.REF#3312 REF#3313

So, if you buy a Probiotic supplement with Prebiotics or Postbiotics, expect to see different units of measure.

What is the Best CFU Count for Probiotics?

This is a big question shrouded in various theories, emerging science, anecdotal evidence, and experts' opinions.

The answer is it depends on many factors, including but not limited to:

  • The specific strain of probiotics 
  • The individual and their health concerns
  • The quality and integrity of the probiotic strains (some are more robust than others)
  • The type of probiotic product (food, supplements, skin care, etc.)

A general range would be from 100 million to 1.8 billion CFUs. But again, this depends on various factors—and more does not always mean better.

Probiotics are generally very well tolerated, with digestive upset occurring if too much is taken at one time.

If you’re looking for strain- and health-goal-specific dosing information, this referenced chart from the World Gastroenterology Organization, which is a compilation of optimal probiotic dosage based on current research, may prove helpful.

Talk to your healthcare practitioner about optimal individual dosing and strains.

CFU Recap

  • CFU stands for colony forming units and is used as a unit of measure for probiotic bacteria
  • Prebiotics and Postbiotics are measured by weight using milligrams (mg) or grams (g) and not by CFUs
  • The number of CFUs in various probiotic products varies widely, from 100 million to 1.8 billion, and more does not always mean better.
  • Talk to your healthcare practitioner about the best CFU count to meet your needs.

Interested in learning more about Prebiotics, Probiotics, and Postbiotics? Check out:


  • 1. , "Colony-Forming Unit", ScienceDirect..
  • 2. , "A simple and fast method for determining colony-forming units", Applied Microbiology International. Volume 47, Issue 4. October 2008. Pages 275-278..
  • 3. , "Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics", Nature Reviews Gastroenterology & Hepatology. .
  • 4. , "Postbiotics in Human Health: A Narrative Review", Nutrients..