Led wattage specs (output draw vs output in lumens)


So I was thinking about this for a while now…

A 1200w LED such as mine will draw 230-250watts from the plug (draw)

Even though it is a rated 1200w light (meaning compared to HPS or MH)

So my light it puts out the lumens of a 1200w HPS or MH, but draws only 230-250 watts of power from the plug…

Meaning the efficiency of LED still will give you lumens you need (formula wattage divided by sq ft)
My grow space is 4x4 so 16 square feet

1200watts divided by 16sqft is 75 watts per square foot
If I use the wattage pulled by my plug, it would be 250watts divided by 16sqft which is a measly 16watts per square foot.

So what I’m trying to get to is, the light produced by my 1200w is more than what the plug draws so are we doing our math correctly?

@FloridaSon @Countryboyjvd1971 @BondPacker @Majiktoker @yoshi anyone else I didn’t tag I’m sorry I have no idea who to ask about lighting :+1::v:

First grow, White widow Autos


The 1200 watt rating is output equivalency of the LED bulbs, if I understand correctly. Too early for math for me, lol

Good Question.


@bob31 I kno I have been trying to find facts about lumen output versus the power draw from the plug. We might be over doing lighting costs! Potential savings are great

Unless the rule of thumb is you need minimum 50 watts per square foot (meaning plug draw)

But that doesn’t make sense, because you need to do the calculations on lumens not power draw. Your just forgetting about how much light it produces and your focusing on saving money at the meter per kw :+1::smirk:


I think what is important more than anything is the penetration of the lights. If you have parts of your plants that aren’t getting light, then they aren’t producing. I’d be interested to hear from the others on this as well.


Maybe it just won’t grow “as fast as you want” I’m more of a patient kind of person :wink:


Im thinking if they arent getting enough light you wind up with popcorn buds and other issues.

another good reason for less lights and scrog or other techniques to maximize the lights you do have.


Yes your correct you end up with “airy” buds

I plan on using this one 1200w for one plant so I think she will be okay :+1::smirk:but it’s the thought if I should get another 1200w just for back up or for reinforcement in flower :thinking:


you are using about 4x the output equivalency that I am using for one plant


Perfect then (yes I’m going to try it) :joy:

4ft from top of seedling/sprout
3ft from top in veg period and lower it each day till I find the sweet spot
2ft from top in flower stage and lower each day until the sweet spot is found :+1:

Once I master one plant grow I will germ 2 seeds and go another round!


awesome. I’m growing an AK. I’m about a month from the day she emerged from the ground and I started on a t5 at about 2-3 inches and then switched to the 300/ 140 watt generic LED when she was about a week old. Been on the LED ever since. My power meter barely moves, on the side of the house, lol.

I do have two more 300/140 lights, but I don’t really think I will need them. I may add one more to my tent once we get towards the end of veg just to make sure I have good coverage.


sweet bro, your doing the right thing​:+1: I would definitely throw that second led in when your switching to flower, or even the last week you veg throw it in and she will be adjusted and used to it for flower :+1:

Something to look forward to, energy savings are guaranteed with LEDs :joy: Glad your meter stays in check :+1:


yep, I agree. It would be a waste of light right now.

I have her in a 3 gal soft pot and she is only about half as wide and not quite as tall. She has tripled in size in the last 10 days though. Just got off to a slow start.


Awesome brother I think I’m following along your grow :+1: Tag me otherwise if I can’t find it and don’t pop in for a few days. Good luck I wish you a happy harvest!


I’m not sure of the math. If @Iva is still around, he’s the guy I go to with LED questions. I haven’t seen him around for awhile, but if he is, he’s most helpful.

I think we can use the equivalent, but he’ll have the answer…


I may be wrong on this, but I would think the lumens are the most important numbers at various heights. The plants don’t care what wattage you are pulling, just how much light they are getting. So if a 1000w pulling 400 actual watts led has the same lumen output as 1000w HID the plant shouldn’t care.

It is like an algebra formula, we don’t care about the input because it can change as long as the output is constant.


When you look at leds they are measured in nanometers instead of lumens


I don’t think leds actually produce the same amount of light
Leds produce the correct useable light that benefits plants and not the unusable light that hps and other need to be very bright in so they reach those spectrums @AmnesiaHaze at least this is what I’m understanding
@Niala might be able to help explain this ?


isn’t there something like the inverse square law of radiation MacG liked to talk about, every inch light travels away from the bulb the growing properties of the light diminish.

I dunno if this helps

"In general minimum amount of lighting needed is around 2000 lumens per square foot.
Optimal is around 5000 lumens to 7000-10,000 or maybe even more, lumens per square foot.
No matter the type of light, if you can find the exact specs for its lumens/FLUX per square foot (or the equivalent PAR for red/blue only LEDs) you can use this as a loose guide as to what you need as minimums:

Seedlings and clones require about 400-1000 lumens per square foot.

Vegetative growth requires about a minimum of 2,000 to 3,000 lumens per square foot.

Flowering requires about 5,000 to 10,000 lumens per square foot, ideally, and can take possibly much more.

10,000 lumens is supposed to be about the average power of the sun at sea level on a clear day at high noon, or something like that, lol.

8,000 - 12,000 lumens is supposed to be about the power of the full sun without any overcast or no clouds.

It’s not ideal, but you can make do with 2,000 lumens for an entire grow if necessary."


Lumens are very much applicable to LEDs. Here is an excerpt:
At last, the LED light bulb arrived on the scene. Now we are talking even lower power consumption for a comparable light output and those watt consumption numbers continue to go down. “Wattage” is no longer a valid reference point. “Lumens” is however, a valid reference point. That is a stable measurement of light output that will not vary as LED light bulbs continue to get brighter and more efficient. Lumens per watt is even more important

Nanometers are important as well, this is the measure of the light output wavelength, or type of light and not an indicator of the intensity of light :slight_smile:


You’re absoletly right @JTheH, it’s a common misunderstanding between equivalent and actual draw “wattage” .

The actual draw is only to demonstrate that they are using less Watts from the wall and are express in watt to facilitate the customer to calculate the kilowatt hour consumption and show the difference in electricity gain of efficiency

The equivalent “wattage” is for the equivalence of lumens,lux and foot candle produce by a real draw light, example : 1000 watts hid draw 1000 watt and have a certain amount of lumens, lux or foot candle value to it, an equivalent 1000 watts draw about 200 watts, however, it has the same lumens, lux and foot candle as the 1000 watts hid.

Of course, some led compagny take advantage of this misunderstanding and cheat on the equivalence factor, so, be an inform customer, and do your homework before buying.

Hoping that’s enlighten a little on this controvertial subject

~Al :v: :innocent: