Grow light wattage ratings

When I buy an LED bulb from the hardware store they rate the bulb at 100 watts equivalent and state that it only requires 20 watts to operate, fine a cost savings on energy. Now I’m seeing that they do this with grow LEDs but I believe in this case the equivalent wattage means nothing. For growing energy don’t I want high operating watts?


They are making a comparison of LED (20 watts) against incandescent bulbs (100 watts.) The comparison isn’t relevant for growing. It’s a meaningless metric. Power draw from the wall is what matters in horticulture. You should run ~40 to 50 watts of high quality LED lighting per square foot of canopy space.


Like you’re reading my mind bro! One more ad gimmick to sort through when buying a grow light.


There are several very deceptive and misleading description in this amazon add. It was the first light I clicked on when I searched for “grow light”

1000W is 10W led X 100 pieces. Not sure how they came up with 1200w. Maybe UV & IR. Either way it is meaningless.

About this item

  • :tulip:【LOW COSTS & HIGHER EFFICIENCY】 Constructed with100 pcs dual-chip(10W) LEDs which is much brighter and more efficient than traditional 1000w hps grow lights ( only consumes 70w), scientifically engineered to keep the balance of the PAR/Lumen Output and Coverage.Effectively promote plant growth, improve crop yield and quality.

Although it is promoted as a 1000 watt light it only draws 70 (I highlighted the above text). As @MidwestGuy pointed out, this is enough power to essentially light a shoe box. I down sized a bit because of the crappy LEDs more than likely used in the light.

This is a very common example of many if not most grow lights sold on amazon. FWIW


I know misleading and confusing!

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The misleading part is what gets people in trouble. The light is probably adequate if you were growing a head of lettuce (is a low light plant) but not cannabis.


I feel empathy for the beginning grower, or maybe I should say sympathy.
There is no excuse for how misleading Amazon is!
But I also don’t like the way online suppliers just copy and paste the manufacturer’s literature. So most of what you read online is biased, and is just the manufacturer’s unchallenged claims.
I know all the different techniques and opinions here on this forum is confusing as well. But, you beginners out there, will be much better served by obtaining advice from those who are not trying to sell.


Part of the problem is the way we measured light before led. Describing the amount of light by watts was never an accurate description, lights should have been sold by lumens. Now we have leds and manufacturers try to express the led lumens in watts since that’s what everyone is used to recognizing it by, which is fine for everything except growing lol