#### Bignutes

##### Well-Known Member

Light follows something called the inverse square law, in layman’s terms it’s just that light intensity fades quickly with distance away from a light source.

Now let’s say the optimum lighting is one that covers your grow space well, like if you have a 2x4 space your light is 19”x46”, almost complete coverage. Do you want 45 w/sqft or 35, or 25?

If we have a set point that 35 W/sqft at 18” as our starting point, the question I had is what if I ran my lights at 30 W/sqft or even 25 W/sqft, at what height would I need to run to be the equivalent of 35 W/sqft.

Below as shown the first number is watts per square foot, calculated by taking the true wattage of your light divided by the length and width of your light, second number is the height at which you should hang your lights at to be equivalent to 35 W/sqft

At 45 it’s 20.4”

At 40 its 19.2”

At 35 it’s 18”

At 30 it’s 16.7”

At 25 it’s 15.2”

At 20 it’s 13.6”

What this tells me is that you can run a light at the lower wattage per square foot but it needs to be at a lower height to have the same performance as a light running at higher wattage per square foot.

By taking this into consideration, getting 1g/w at 35 W/sqft should increase to 1.4 g/w at 25 W/sqft considering all other variables are equal.