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PAR, PPF and PPFD Explained: Understanding Lighting Metrics

Posted by Codisto Collaborator on

When you are searching the market for a new LED grow panel, you have probably come across incomprehensible scientific terms, such as PAR, PPF, and PPFD. Manufacturers and reviewers often quote these obscure acronyms as important indicators of a unit’s efficiency.


But what do they really mean?


In this article, we would like to dig a little bit deeper into the science behind LED panels. That’s why we are going to explain these fancy physics terms in a way that everyone can understand!

What Is PAR

The acronym stands for Photosynthetically Active Radiation and refers to the total energy required to support the growth of your plant. PAR is measured in mmol/m2, and its values range between 0-3.000mmol/m2.

In nature, highest PAR levels are associated with hot summer middays and reach zero in the night. To put it even more simply, it is the total light available for the photosynthesis of your plants. You can measure the PAR levels in your indoor garden by a detector that measures light from 400-700nm.

What Is PPF

PPF stands for Photosynthetic Photon Flux, and it refers to the total number of photons emitted per second within the PAR region. PPF is measured in μmol/S. Practically, PPF does not have a lot of practical use but is necessary to determine the PPFD, which is key in determining the efficiency of a LED panel

What Is PPFD

PPFD stands for Photosynthetic Photon Flux Density, and it is used to measure the PPF in the PAR region per m2s (square meters per second). Essentially, PPFD is a field measurement, which determines the light footprint of a LED unit at a set distance from the source of light.

Density is critical because it ties down the production of energy to a specific area. Of course, these levels are not the same everywhere and change according to the height of the LED panel and the distance from the center of the light.


When measuring the PPFD, you should take into account the distance from the light, the dimensions of the grow area and the intensity of the light.

What Am I Supposed To Do With All This Information?

The light intensity of your LED panel should be your top priority. Plants make their food from light and the stronger it is, the better (full-spectrum AND intense is ideal). PPFD is the horticulturist standard for measuring light intensity. But how much do your plants need exactly?

The answer is tricky because different plants have varying needs. As a rule of thumb, anything above 700 μMol/m2s at a 12/24 light cycle will get you decent results. If you are running your plants at longer light cycles, you should aim for a lower PPFD value (around 300 μMol/m2s).

PPFD measurements will vary depending on the distance from the canopy and the precise area of measurement. If you measure the light on the edge of the light footprint, the PPFD indicator will drop and will raise as you move to the center.


Our customer experience team is available 24/7 to solve all of your questions regarding the specs of your LED grow light!









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