PLENNY LEARN · MICROBIAL TEST RESULTS
Read the unit before judging the number
CFU/g means colony-forming units per gram. On a cannabis certificate of analysis, it expresses a microbial count relative to sample mass. It is not a THC percentage, a count of visible mold spots, or a safety verdict by itself. Read it with the organism or group tested, the method and the applicable limit.
By Plenny · Updated September 19, 2026 · 4 minute read
What does CFU/g mean on a cannabis COA?
In a culture-based test, a colony-forming unit represents microorganisms capable of producing a colony under the test’s conditions. The “per gram” part expresses the result relative to the mass of the sample. It does not mean the laboratory counted every microorganism in an entire package.
Colony-forming units: a culture-based measure tied to the method’s growth conditions.
Per gram: a mass-based reporting unit. CFU/mL uses volume instead.
The unit does not identify the organism. Read the row label, such as total yeast and mold.
FDA’s aerobic plate count chapter explains how colony counts and the amount of original sample represented are used to estimate microbial concentration. It is a food-testing reference for the measurement principle, not a cannabis action-limit table.
How to read scientific notation and less-than signs
These fictional entries demonstrate notation only. They are not recommended limits, real batch results or evidence that a product passed.
2.5 × 10³ CFU/g: how much is that?
2.5 × 1,000 = 2,500 CFU/g
The notation 2.5E3 usually represents the same number. Keep the unit and test name attached when comparing results.
<100 CFU/g: does that mean zero?
No. The less-than sign says the result is below the stated value under the laboratory’s reporting convention. It does not provide an exact count of zero. Check the report legend and ask whether the value is a detection or reporting limit.
ND beside a named organism: can I compare it with 100 CFU/g?
Not directly from those labels alone. A presence/absence test and a numerical count may answer different questions. Check the target, method, units, sample amount and the laboratory’s definition of ND.
Total yeast and mold is not every microbial test
A broad count and a test for a named organism have different scopes. A total yeast and mold entry does not identify every species contributing to the result. A result for one target, such as Salmonella, does not describe every other organism.
SC Labs’ testing menu lists total yeast and mold, total aerobic bacteria and specific microbial targets separately. Read which tests were actually included instead of treating one row as the entire microbial panel.
Plating and PCR do not measure the same signal
SC Labs explains that its qPCR testing detects DNA from specified organisms and that it also offers plating methods. Because the measurement principles differ, do not treat a PCR result as a literal count of colonies grown on a plate. Ask the laboratory how it validates and reports the particular assay.
What CFU/g is considered safe in cannabis?
There is no single number that answers this for every organism, product and testing program. Identify the relevant specification and read the laboratory’s reported pass/fail decision. A count without that context cannot establish compliance or suitability for a particular person.
ACS Laboratory distinguishes microbiology testing from mycotoxin testing. Mycotoxins are chemicals that certain molds can produce, and they can remain after the mold is no longer alive. A microbial result therefore does not substitute for a mycotoxin result.
A low count on one row does not verify the rest of the report. Check the relevant panels, sample identity and laboratory notes. Do not use this page to override a failed result or dismiss suspected contamination.
Four checks before interpreting a microbial result
If information is missing, a useful question is: “What exactly does this row measure, what reporting limit applies, and which specification determines the result?”
Common questions
Is CFU/g the same as a percentage?
No. CFU/g expresses colony-forming units relative to mass. A cannabinoid percentage expresses a mass fraction. The units describe different measurements and cannot be converted into each other.
Is CFU/g interchangeable with CFU/mL?
No. One is per gram and the other is per milliliter. Do not compare the numbers directly without knowing the material, method and any valid conversion used by the laboratory.
Does a pass mean the sample is sterile?
No. Passing means the reported result met the particular specification applied. It does not establish the absence of every microorganism, toxin or other contaminant.
Keep learning
Sources and scope
Sources checked September 19, 2026. Laboratory resources describe their own services and reporting methods. This guide explains terminology and does not certify a batch, supply a universal safety limit or replace current program requirements.
Chris Garcia, Owner and CEO
September 19, 2026
How this page is prepared: Plenny uses linked research and other relevant sources for educational explanations, and product details and batch COAs where relevant. General strain, flavor, and effect descriptions are not guarantees.
Commercial transparency: Plenny sells products discussed on this website. Educational pages are not medical or legal advice, and content is not medically reviewed unless a named licensed reviewer is shown.