Lighting ppfd to fc

Sorry im not that tech savy fairly new to this and just flat out bad with math and computers so im trying to figure out my lighting ppfd it says
100-300 for seedling
400-600 for vegetation
800-1000 for flowering my issue is i have a good meter for FC & klux but i cant find anywhere how to convert the reading for my lighting its LED BLUE/white for veg and i believe blue/red for bloom im sorry if this is a confusing or just ridiculous question but its been 2 days of throwing my phone trying to perfect my setup for now an when they get bigger

PPFD requires no conversion. It is accurate as read from the meter you are using and that reading accounts for spectral differences automatically.

If you have a light with veg/bloom switch, then you should be running with both on for the duration of a grow.


No sorry i know what the ppfd should be , but i dont have a meter that reads it … my meter only reads foot candles and klux and im trying to convert what my meter says into what the proper ppfd is so i can raise or lower my light to the proper level

The conversion of lux to PPFD is heavily influenced by the spectrum profile put out by the light. HLG has a conversion table, but if you are using a light with veg/bloom switch, then the HLG conversion table will not be accurate since there are large spectrum differences btw the diodes HLG uses and whatever diodes your light is using.

I’ve never seen a conversion table relevant for your type of lighting.

Have you tried the Photone app? It reads in PPFD and while it won’t be wholly accurate, it is the best you are probably going to do.


I’d like to add that the reason there isn’t a quick and dirty conversion is that lux measures only the visible spectrum of light (roughly 400 to 700nm.) Plants see a slightly wider spectrum of light that is measured in PPFD rather than lux. The wider spectrum that is unaccounted for with lux extends to ~370nm to ~800nm. True PPFD measurements account for this wider spectrum.

Additionally complicating things is that each model of light has it’s own unique spectrum that will impact both total lux and total PPFD.


Plus, primo lights are deficient in green.

Personally I would look at the plants to tell you how they are doing. If they’re ‘leggy’ then lower lights/raise power. If short and squatty then do the opposite. Lights should be turned all the way up once you start a 12/12 cycle.


HLG>COM website has “resources” tab.
Under resources, calculators tab.
Conversion of LUX to PPFD can be done.
Happy growing to you.

UT383-BT light meter used.


the app photone allows you to measure your grow light output.

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and for android, PPFD app, Called PPFD Meter in google store


Online there’s plenty of conversion charts or calculators.

Ppfd is not able to convert as they both use different types of readings so real world that’s why a ppfd meter cost ten times what a FC/lux meter does.


Somehow, my phone and the app I used were not trustworthy.
My UT383-BT is trustworthy, I believe.

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