Led wattage specs (output draw vs output in lumens)


Hey @AmnesiaHaze, the calculation method is

You need at least 35 watts per square feet for led light , so you have 16 square multiply by 35 , so 560 watts is a minimum

And if you go with the ratio of 50 watts per square feet, it’s 800 watts should be suffisant

So your 1200 watts equivalent led light is perfect (more watts mean more lumens, mean more light penetration), just have good mylar reflective material to assure a better coverage or put some appoint light to achieved it :grinning:

Hoping that’s helping you AmnesiaHaze

~Al :v: :innocent:


Wow thanks for all the well detailed explanations everyone! You have cleared my head out from the nonsense. It all is coming clear to me now :+1::v:

I get some additional lighting, well because why not? I’ll probably get a couple cfls for the side lighting and maybe a couple t5 fluorescent 4ft fixtures and have 5100k and 3100k

Which light is for vegetative and what is for flowering? 5100k and 3100k

@Niala your explanation made the most sense to me, as well as @JTheH and @kabongster thanks guys as well as everyone else that helped me out @Countryboyjvd1971 @Majiktoker @FloridaSon


3100 Kelvin is the more appropiate one for flowering @AmnesiaHaze, every thing above 5000 Kelvin is for vegetative stage :wink::innocent:, Oh and just make sure that you can control the heat (more light more heat) :wink: and you’re welcome :innocent:

~Al :v: :innocent:


Thank you @Niala your the bestest friend a friend could ask for haha :joy::+1::v:


Because of so many sellers fudging the numbers, different leds, how they are powered there would be close to no way to make an accurate equation to measure energy input to light output.

To get 1200 worth of light on the (old scale) out from 250w in would have to be a well thought out and made light.
I would guess the 1200 is closer to 600 out put or 800 max but I could be wrong and it would not be the first time.

I made a light I am using now with 12 100w led cobs with a max power usage of 1200w (from the wall) but I am running them at around 40% (supplying 60% less mil amps to each led unit but the same voltage) so I am pulling only just under 500w from the wall but is still supplying 70-80% of the 1200 (old scale) possible light and the leds last longer run at lower % but still out put a higher % of light then what is be supplied in energy with the sweet spot of price verses output around 50-60%.
You could run 12 at 20% using 220w from the wall but out putting 600-800w ish (old scale) but the cost for parts would be higher due to more Leds.
This makes a measuring Leds close to impossible to work out draw to lumens and alot of seller use this to sell low end light at top prices. Over the last few month I have test alot of led units and most are not what they state on the box so to speak.

This isnt that helpful but it will help exlain why its hard to work out a simple equation for Led wattage.


Thanks so much @Iva

You made a lot of sense, I understand your (old scale) reference, my 1200w is straight up made from china, in a way you could test with a lumens meter, might invest in one as well as a thermo cam so I can see foot print when raising or lowering the lights. It will give me my proper canopy temps :+1::smirk::crossed_fingers:

The light has 6 200w cob leds, with a rating from the manufacturer saying it’s pulling 250w-270w

Now I also think you forgot what I mentioned earlier, the led light will put out more lumens with less wattage, hence why everyone’s house hold lights are slowly being converted to leds from incandescent or fluorescent bulbs, why because they are cheaper to run but they put out just as much light if not more.

So back on to my original topic. My 1200w rated led is supposed to replace a 800w HPS or MH, BUT the 1200w has a different foot print so let’s not get off topic.

The 1200w is basically the projected lumens of a larger HPS or MH with the benefits of full spectrum, and it costs less


You know what more I think of it, my 1200 will replace a 1000w

I should make a scale/chart for reference as to what led will “compete with” as far as HPS and MH what do you all say! :wink::+1:haha


:raised_hands:t3:Well said my friend


Although I appreciate the tag @AmnesiaHaze, I am probably the worst one on here to ask about lights, as a solely outdoors grower I know a whole lot of nothing about them :joy: but, thank you for the tag cause it looks like some very interesting replies which I’m keen to read through and learn a bit :smile:


Some charts :+1:


I don’t use watts or light with leds just watts from the wall as I said its impossible to guess what an LED is really making with out looking at the LEDs and the power supply to work out it out and most ppl dont like their LED units opened to do it.

I use this for testing LED units they measure a wider spectrum out side what we can see and that normal lum meters cant detect as well.
Also after growing with spiderman LEDs and natural light LEDs (more white light) the white light makes a noticeable difference in the plant that looks more HPS shape and heavier feeling buds but that what I have found and may just be my plant.

Have you got a pic or a link for your light I think I know what it is but not sure.
Working out LED setups can be a bugger of a thing to do and best done before medicating :slight_smile:



CrxSunny 1200W COB LED Grow Light Full Specturm for for Hydropnic Indoor Plants and Greenhouse Growing Veg and Flower https://www.amazon.com/dp/B01MQOOTTS/ref=cm_sw_r_cp_apip_ZPQLqI1q65Z3N



There are many opinions on the question of “how much light is needed for growing marijuana indoors”.The info below, on lumens or watts per sq/ft, is only a general guideline to how much light you really need. The type of lighting used (High Pressure Sodium/Metal Halide, Compact Fluorescents, T-5, L.E.D.) as well as the stage of plant growth – seedlings: less light, vegetation: more light, flowering: most light. General rule of thumb is – Throw as much light on them as you can, with respect to heat, safety and affordability.
To determine how many lumens per square foot you have:

Find out the square footage of your space.
Width x Depth = Square feet. Divide the lumens available by your square footage.
This will give you lumens per square foot.

Example: Say your space is 3 feet deep by 4 feet wide, 12 square feet. The total lumens available from your light(s) is 45000 lumens. 45000/12 = 3750 lumens per square foot.

To determine how much light you need in watts?
The general rule of thumb for providing light for an area is a minimum of 30 watts per square foot but 50+ watts per square foot is optimal. You can determine the proper lighting for your area by using this formula:

50 watts (or the total watts you are using) x (your square footage).
Example: You have an area of 10 sq. ft. – 50w x 10 s.f. = 500watts/sq.ft minimum or 50 watts x 10 s.f. = 500 watts/sq. ft. (optimal).

Also, remember that fluorescent’s are weaker and emit less light than an HID. This means you will need 5 times the amount of wattage to equal the output of an HID. So, 30 watts of HID would equal 150 watts of fluorescent’s. This is why it is advised to provide a minimum of 30 watts per square foot for HID lights and aminimum of 150 watts per square foot for fluorescent’s.

I got more info if you need it



For that price thats a pretty good light !
be careful not to spend too much time under them because they have UV and ir or use sunblock.
Two of them in a 1200x1200mm space would be really good.
Start with one add second one just before swapping to flower happy plants
I have 12 cobs running at about 45% I use six at the start and swap to twelve two weeks before I swap the clock.
220w per bank and no fans. This is more light then I need but not too over the top but I found six to be only just enough.
LEDs are very hard to gauge on the watts or lums and I have never found a good guide to LED light per foot that made sense to me.


Thank you for dropping by, Brother. I haven’t seen anything from you in a while. How have you been?

I have that same light, but you have me a bit concerned. These lights aren’t adjustable with output. Does that mean I will need to get another one if I decide to flower indoor?

My plan is to use it for mothers, though I also have two Blueberry autos under it for a full grow. I’ve been reading and have noticed people increasing their lights for flowering. Is that necessary?

Thanks again…


You don’t need to add more. Lights @FloridaSon
You can just lower you light when you get closer to flower but depending on how many plants and size of canopy you may need to add a second or third light once canopys fill out
If you stay with in mfg foot print with the canopy you’ll be fine with one light
Having a extra light wouldn’t hurt though
But at Iva can explain better I’m sure I’ve read a bunch of his stuff and he seems to really understand the led light thing :+1:
Hope this helps bro


Yeah, he’s the one I go to for most of my LED questions. I think he heads the LED black ops!! LMAO


I hear that Again I’ve read a bunch of his posts and he seems extremely knowledgeable on these matters


I have had some real life problems but I am still here so thats a win

You dont need two but it would be better but not twice as good.
I grew with about the same as one of those lights and found the plant grew stronger and less fluff with more light but I was lazy and just doubled the setup and now there is a noticeable difference and have shut down becasue I have too much, Isn’t that cool :joy: never had too much before.

If they are 200w cobs x 6 (1200 max) and you are using 250ish watts from the wall they are running at less then 25% or so. My math is based on 220v 50hz but the difference should be minimal.
The cobs on this unit are the wide spectrum ones they are more white then spiderman LEDs but still have a little bit of a pink look to the light. I have never seen 200w ones but this dosn’t mean they arn’t there.
LED tech is really moving along now.


Thank man you reminded me about HID, although I did post a chart comparing them and it still didn’t ring a bell. So thanks for putting it in the memory bank :+1: @garrigan62

@iva I have a pair of uva and uvb sunglasses coming soon!

@FloridaSon don’t need to worry, just give your girls a little more breathing room, and only during your sprout/seedling stage. Once they reach veg stage, your fine with full power and 36" and lower each day to find the sweet spot