Footprint Shape

LED grow lights come in a wide range of shapes. Some are round, some are square, but about half of the lights reviewed here are rectangular. There's nothing wrong with a rectangular light; depending on your particular setup, rectangular lights may even be ideal–the key is to find a light with a footprint that matches the shape of the area you're trying to grow in.

Of course you can get 2 or more lights to cover a rectangular area, or even get a light mover to change the shape of the footprint (not so much change the total coverage area, but the shape–and if you get the right one, light movers are awesome!).

But whether you're getting one light, multiple lights or using a light mover, you still need to know the shape of the lighting footprint that the LED panel will put out to properly plan coverage for your growing area. Most of the LED vendors helpfully provide the suggested lighting footprint for their light.

However, after getting burned by a light that didn't cover the advertised footprint at any reasonable height, I started noticing just how many advertised footprints are wrong based on the shape of the light itself. Figuring out the shape of a light's footprint is fairly easy; light spreads out evenly in all directions from an LED no matter what the lens angle is; the lens angle only controls how fast it spreads out as you increase the light's height. The shape of the footprint is dictated by the shape of the light itself.

In the table above, companies that advertise footprint shapes for all of their lights which are within 90%-100% of the actual footprint shape are placed in "The Good" column. Companies advertising footprint shapes for all of their lights within 75% of the actual footprint shape are placed in "The Bad"; those with any lights less than 75% are in "The Ugly". Apache Tech does not provide information on the size of their lights, and Truth Lighting provides no suggested footprint sizes, so they were placed in "The Unknown".

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Calculating an LED Grow Light's Footprint Shape

For an example of how to figure out the lighting footprint shape, Hydro Grow's 168X-PRO 270W light is extremely long (48 inches) and narrow (6 inches); if the light is raised to whatever height it takes to spread the light from each LED out to a circle 12" across (6" in radius), the total length for the footprint would be 48" (light length) + 6" on one end of light spread + 6" on the other end for light spread, which is 60". At the same height, the footprint width would be 6" (light width) + 6" light spread + 6" light spread = 18" footprint width. And indeed, the 168X-PRO 270W light is advertised as having a 60"x18" footprint, so if you hang it at the right height, you're getting 100% coverage of the advertised footprint shape. (I chose the LED light spread of 12" in this example because it demonstrates that this advertised footprint is the correct shape. I find it interesting that Hydro Grow can get some of their footprint shapes completely correct, and yet be horribly wrong on others.)

Hydro Grow 168X-PRO footprint coverage diagram

Lush Lighting's Dominator light is also extremely long (35") and narrow (8.5") and is advertised as having a 48"x48" footprint. To get one side of the actual lighting footprint to be 48", we would need to raise it to whatever height it needs to be to get light spreading out in a 13" diameter circle from each LED (6.5" in radius, but 13" in total from the ends and sides of the light) so the actual footprint would be 48"x21.5". So the actual footprint is (48 * 21.5 = ) 1032 square inches, but the advertised 48"x48" footprint is 2304 square inches. Covering only 1032 of the advertised 2304 square inches means that only (1032/2304 = ) 44.8% of the advertised footprint is being covered at whatever height it takes to get a 48" long footprint.

Lush Lighting Dominator footprint coverage diagram, light hung low

But wait– we can raise the light higher to spread the light out more and get it to cover the full 48" advertised footprint width. The light's width of 8.5" means that the light would need to spread out 39.5" total (19.75" on each side) to get it 48" wide. At this same height and light spread, the footprint's length is now (35" + 39.5" = ) 74.5", so the total footprint area is (48 * 74.5 = ) 3576 square inches. The original advertised 48"x48" footprint is 2304 inches, meaning that (3576 – 2304 = ) 1272 square inches of light are now falling outside of the advertised footprint and are wasted if you were planning on the 48"x48" footprint. 1272 wasted square inches compared to the originally advertised 2304 inches means that (1272/2304 = ) 55.2% of the light is wasted, and that you're only using (100% – 55.2% = ) 44.8% of the light being produced if you hang it at that height.

Lush Lighting Dominator footprint coverage diagram, light hung high

So if you hang Lush's Dominator high enough to match the advertised footprint length, you're only getting 44.8% of the advertised area to grow in, and if you hang it high enough to cover the advertised footprint width, you're only using 44.8% of the light you're paying for. If you split the height difference in half, you'll get half of your wasted footprint area back, but you'll still be wasting half of the wasted light off the ends. In other words, it doesn't matter what height you hang the light at, you're always only getting 44.8% use out of your Dominator light compared to the advertised footprint– less than half of what you were expecting.

Calculating this "coverage score" for all of the lights compared here, it's shocking how badly most of the LED sellers have done at giving accurate coverage footprint shapes for all of their lights. It isn't just rectangular lights either– some square lights have rectangular advertised footprints!

A coverage score less than 100% but higher than 90% is pretty good; you probably would never notice that the lighting footprint isn't perfect, and I'm not going to say that a light with a score above 90% is bad. In some cases, rounding off numbers may be the reason a score isn't 100%. For example, if I were an LED vendor and my light footprint was 19.6" long, I'd just call it 20".

In California Light Works' Solar Storm series of lights, the coverage score is somewhat unfairly skewed by having the UV fluorescent reptile bulbs hanging off the side of the LEDs. In the Solar Storm 880W's case, the LEDs themselves are almost square and the light's shape is made even more rectangular by the fluorescent tubes. It still scores above 90%, so this isn't being unfair to it. For the Solar Storm 440, the LEDs are spaced out at least twice as long as they are wide, and the fluorescent tubes make the light fixture itself more square, giving it a score above 90% when it really doesn't deserve it. Without having an accurate measurement of the LED dimensions, I can't say what the score should be, but it would likely be around 50%.

I should note that some of the LED vendors such as G8LED only gave coverage footprints for their lights in square feet and did not give a shape; for these I calculated the perfect footprint shape to cover the given area so they would get a 100% score. It's easy to see in the table which lights these are, as they have fractional inches in the footprint dimensions.

Footprint Shape Comparison Graph

To summarize again, scores from 90-100% below are good, 75-90% are questionable, 50-75% is really bad, and those less than 50% are shockingly bad.

Loading graph…

Less than 90%: Poor Performers

For lights that have less than 90% but more than 75% of the advertised footprint adequately covered, you'll likely notice that plant growth would be uneven in the advertised footprint. At the low end of 75%, you're not getting ¼ of what you paid for.

Less than 75%: Have they Actually Tested These?

For lights with less than a 75% coverage score, it means that at least ¼ of the advertised footprint isn't getting direct light, or that if you raise the light to fix that, more than ¼ of the light is now wasted shining outside the footprint.

Human eyes are actually quite bad at discerning differences in brightness, so you may not notice obvious uneven coverage for a light with a score of 75%, though your plants would. It makes me wonder where they come up with some of these footprint sizes, because it probably wasn't from a growing test, and clearly wasn't from scientific measurements or even basic math. This makes me nervous about accepting any of their other claims.

Less than 50%: Unshapely Lies

Even to a human eye, it would be obvious if you plugged in a light with a 50% or lower score that the shape of the light footprint isn't the same as the advertised footprint shape. To me this indicates that they've never even plugged these lights in to examine their claims, or that they are lying to try and sell you lights– either way I wouldn't recommend buying them.

Lush Lighting's coverage scores go all the way down to 26% for the Dominator lights, meaning that almost ¾ of the advertised "intense coverage" footprint is unusable or that ¾ of the light is wasted if you pull the light up high enough to cover the full footprint width. If they are giving such grossly misleading information about footprint shapes, it really makes you wonder how else they're trying to mislead you.

Footnotes

Illumitex Footnote:

The Illumitex NeoSol DS light has an innovative feature that allows you to change the angle of each of the individual bars that make up the light so that you can aim them out to get more even coverage. This is a very neat feature, but even if you angle all the bars out perfectly, it still won't give you even light coverage for a square footprint. This is because the light has to travel further to reach the outside of the footprint, and due to the inverse square law of light, the further it travels, the less intense it becomes. So even with all the bars properly aimed, right under the center of the light fixture the light will be intense, but on the sides of a square footprint parallel to the long dimension of the light, where it has to travel the furthest, it will be much less intense.

If they had put a lot more LEDs on those outer bars than they did on the middle bars, that could start to even things out, but with the current design each bar has exactly the same number of LEDs. Even if they do put more LEDs on the outside bar, the footprint shape still won't be square; the light that has to travel the farthest to the corners of the footprint will spread out more as it travels, so the footprint shape would be something like a butterfly's wings, with lots of light wasted off the corners. It's just really, really hard to get a square lighting footprint out of a rectangular light.

Math Footnote

Figuring out ideal footprint shapes when you only have the size of the light and an area for coverage gave me my first-ever real-world need to use algebra's quadratic equation; it may have taken 30 years, but I guess Mr. Richardson was finally right about it being worth learning! If you don't feel like deriving the equation yourself, and you're trying to figure out the footprint shape for a light of length L and width W, whose footprint is given only as an area A, it's as easy as figuring out the light spread S needed to get the total coverage area, given by the equation:

Equation to determine light spread, given light shape and area

Given the light spread S, the footprint length is then L + S, and the footprint width is W + S. It's important to convert L, W and A all to the same units (feet, inches, centimeters, whatever) for this to work.

Footprint Shape Data for All Lights

The data table is very large- you may need to scroll side-to-side as well as up and down to see the whole thing. Larger screens help! If you're only looking for one company or light model, enter the name in the search to only show those results.

CompanyConclusion RankingProductLight Length (in)Light Width (in)Footprint 1 NameFootprint 1 Length (in)Footprint 1 Width (in)Footprint 1 Coverage %Footprint 1 Coverage PercentFootprint 2 NameFootprint 2 Length (in)Footprint 2 Width (in)Footprint 2 Coverage %Footprint 2 Coverage Percent
Diamond Series DS 100 - Extreme 3w
19.00
5.00
36.00
30.00
73%
30.00
24.00
67%
Diamond Series DS 200 - Extreme 3w
19.00
9.00
42.00
36.00
89%
36.00
30.00
87%
Diamond Series DS 300 - Extreme 3w
19.00
11.00
48.00
42.00
95%
36.00
36.00
78%
Diamond Series DS 400 - Extreme 3w
36.00
8.00
54.00
36.00
72%
48.00
30.00
67%
Diamond Series DS 600 - Extreme 3w
36.00
12.00
54.00
42.00
71%
48.00
36.00
67%
Diamond Series DS 800 - Extreme 3w
36.00
19.00
66.00
54.00
91%
54.00
42.00
88%
XTE Series DS XTE 100 - 5W LEDs
19.00
5.00
36.00
30.00
73%
30.00
24.00
67%
XTE Series DS XTE 200 - 5W LEDs
19.00
9.00
42.00
36.00
89%
36.00
30.00
87%
XTE Series DS XTE 300 - 5W LEDs
19.50
12.00
48.00
42.00
96%
36.00
36.00
79%
XTE Series DS XTE 400 - 5W LEDs
35.00
8.00
54.00
36.00
75%
48.00
30.00
70%
Diamond Series EX-Veg DS200
19.00
8.00
54.00
54.00
80%
36.00
36.00
69%
Diamond Series EX-Veg DS300
19.50
12.00
66.00
66.00
89%
48.00
48.00
84%
Diamond Series XML DS XML 150
12.50
12.50
36.00
36.00
100%
30.00
30.00
100%
Diamond Series XML DS XML 350
19.00
19.00
54.00
54.00
100%
48.00
48.00
100%
Diamond Series XML DS XML 650
25.50
25.50
66.00
66.00
100%
60.00
60.00
100%
AT-120WB (White and Blue LEDs)
14.00
11.00
?
?
AT120RB (Red and Blue LEDs)
14.00
11.00
?
?
AT120W (All white LEDs)
14.00
11.00
?
?
AT120WR (White and Red LEDs)
14.00
11.00
?
?
AT-600-WR2 (White and Red)
?
?
48.00
48.00
?
?
GL100LED Full Spectrum 300W LED
?
?
48.00
48.00
?
31.75
31.75
?
GL80x5LED Full Spectrum 400W LED
13.20
13.20
36.00
36.00
100%
30.00
30.00
100%
Full Spectrum 600 Watt LED
12.00
8.25
?
?
GL140x5LED Full Spectrum 700W LED
15.00
15.00
42.00
42.00
100%
36.00
36.00
100%
Full Spectrum 900 Watt LED
16.50
16.50
?
?
Full Spectrum 1200 Watt LED
18.10
18.10
?
?
GL25LED Full Spectrum 75W LED
6.80
6.80
24.00
24.00
100%
?
GL25LED Full Spectrum 135W LED
10.50
10.50
24.00
24.00
100%
?
GL25LED Full Spectrum 180W LED
10.50
10.50
30.00
30.00
100%
?
W90-3000K
11.25
6.75
100%
20.00
20.00
100%
W90-4000K
11.25
6.75
36.00
36.00
100%
100%
W90-5000K
11.25
6.75
36.00
36.00
100%
100%
PhytoMAX 200
12.00
12.00
42.00
42.00
100%
30.00
30.00
100%
PhytoMAX 400
15.75
15.75
60.00
60.00
100%
42.00
42.00
100%
PhytoMAX 600
18.75
18.75
72.00
72.00
100%
51.00
51.00
100%
PhytoMAX 800
21.00
21.00
84.00
84.00
100%
60.00
60.00
100%
PhytoMAX 1000
21.00
21.00
96.00
96.00
100%
66.00
66.00
100%
SPYDR 600 START-MAX Spectrum
36.24
35.63
?
48.00
48.00
99%
SPYDR 600 GROW-MAX Spectrum
36.24
35.63
?
48.00
48.00
99%
SPYDR 1000 GROW-MAX Spectrum
36.00
36.00
?
48.00
48.00
100%
SPYDR 1200 GROW-MAX Spectrum
36.00
36.00
?
48.00
48.00
100%
Solar Storm 880W
23.00
18.00
84.00
84.00
94%
48.00
48.00
90%
Solar Storm 440W
18.00
15.00
72.00
72.00
96%
36.00
36.00
92%
Solar Flare 220W LED VegMaster
9.00
9.00
60.00
60.00
100%
24.00
24.00
100%
Solar Flare 220W LED BloomBooster
9.00
9.00
60.00
60.00
100%
24.00
24.00
100%
Solar Flare 220W LED FullCycle
9.00
9.00
60.00
60.00
100%
24.00
24.00
100%
Solar Flare 110W LED VegMaster
9.00
9.00
48.00
48.00
100%
?
Solar Flare 110W LED BloomBooster
9.00
9.00
48.00
48.00
100%
?
90 Watt LED All RED G8 Flowering BOOST
10.50
10.50
37.95
37.95
100%
?
240 Watt Full Spectrum G8LED BLOOM only
16.00
8.50
33.38
25.88
100%
?
450 Watt Full Spectrum G8LED BLOOM only
17.50
11.00
44.95
38.45
100%
?
240 Watt Full Spectrum G8LED Grow Light
16.00
8.50
33.38
25.88
100%
?
450 Watt Full Spectrum G8LED Grow Light
17.50
11.00
44.95
38.45
100%
?
600 Watt Full Spectrum G8LED Grow Light
20.50
14.00
54.27
47.77
100%
?
900 Watt Full Spectrum G8LED Grow Light
20.50
14.00
62.13
55.63
100%
?
E60
16.70
8.60
98.40
98.40
92%
?
RX30
16.70
8.60
?
?
L4A Series 10 (refurbished)
23.40
15.20
?
?
LX601 C-plate
16.70
8.60
48.00
48.00
83%
?
LX601 G-plate
16.70
8.60
48.00
48.00
83%
?
LX602
16.70
8.60
78.00
78.00
90%
?
21X-PRO 36W
5.25
5.25
12.00
12.00
100%
?
84X-PRO 120W
11.75
11.75
24.00
24.00
100%
?
126X-PRO 200W
17.50
11.75
36.00
24.00
74%
?
168X-PRO 270W
48.00
6.00
60.00
18.00
100%
?
189X-PRO 290W
17.50
17.50
36.00
36.00
100%
?
336X-PRO 500W
23.50
23.50
48.00
48.00
100%
?
420X-PRO 600W
11.00
11.00
N/A
N/A
Sol 1 (45 Watt Configuration)
8.50
8.50
96.00
96.00
100%
24.00
24.00
100%
Sol 1 (85 Watt Configuration)
8.50
8.50
120.00
120.00
100%
36.00
36.00
100%
Sol 2 (45 Watt Configuration)
12.50
8.50
144.00
96.00
54%
36.00
24.00
67%
Sol 2 (85 Watt Configuration)
12.50
8.50
180.00
120.00
53%
48.00
36.00
78%
Sol 4 (45 Watt Configuration)
12.50
12.50
144.00
144.00
100%
36.00
36.00
100%
Sol 4 (85 Watt Configuration)
15.00
15.00
180.00
180.00
100%
48.00
48.00
100%
Sol 6 (45 Watt Configuration)
18.00
12.50
180.00
144.00
79%
48.00
36.00
82%
Sol 6 (85 Watt Configuration)
21.70
15.00
216.00
180.00
84%
60.00
48.00
89%
Sol 9 (45 Watt Configuration)
18.00
18.00
180.00
180.00
100%
48.00
48.00
100%
Sol 9 (85 Watt Configuration)
21.70
21.70
216.00
216.00
100%
60.00
60.00
100%
NeoSol DS
48.50
24.00
60.00
60.00
59%
48.00
48.00
49%
NeoSol NS
36.50
18.00
?
?
NeoSol LS
36.50
2.50
?
?
H380
4.00
4.00
24.00
24.00
100%
?
H350 (Magenta or Purple models)
4.00
4.00
36.00
36.00
100%
24.00
24.00
100%
H150 (Magenta or Purple models)
2.50
2.50
24.00
24.00
100%
?
H150 Blue
2.50
2.50
24.00
24.00
100%
?
H150 Red
2.50
2.50
24.00
24.00
100%
?
K3 - L300
15.00
11.00
36.00
24.00
67%
?
K3 - L450
20.00
11.00
42.00
30.00
90%
?
K3 - L600
25.00
11.00
48.00
36.00
94%
?
K3 VEG L600
25.00
11.00
48.00
36.00
94%
?
K5 - XL750
23.00
17.00
48.00
48.00
88%
?
K5 - XL1000
26.00
20.00
60.00
60.00
90%
?
90 watt LED Grow Light UV
10.75
10.75
24.00
24.00
100%
?
90 watt LED Grow Light HO (Vegetative Model)
10.75
10.75
24.00
24.00
100%
?
BlackStar 480 watt LED Grow Light HO V2.0
15.75
15.75
36.00
24.00
50%
?
BlackStar 480 watt LED Grow Light UV V2.0
15.75
15.75
48.00
36.00
67%
?
BlackStar 180 watt LED Grow Light HO V2.0
15.75
8.38
36.00
24.00
81%
?
BlackStar 180 watt LED Grow Light UV V2.0
15.75
8.38
36.00
24.00
81%
?
BlackStar 240 watt LED Grow Light HO V2.0
15.75
8.38
36.00
24.00
81%
?
BlackStar 240 watt LED Grow Light UV V2.0
15.75
8.38
36.00
24.00
81%
?
Lighthouse Hydro ION 8 426w FSF LED Grow Light with UVB
12.50
12.50
36.00
36.00
100%
24.00
24.00
100%
Lighthouse Hydro ION 8 1546w FSF LED Grow Light with UVB
25.50
25.50
72.00
72.00
100%
48.00
48.00
100%
BlackStar Chrome 180w LED Grow Light FSF
11.00
11.00
36.00
36.00
100%
24.00
24.00
100%
BlackStar Chrome 270w LED Grow Light FSF
16.00
16.00
54.00
54.00
100%
36.00
36.00
100%
BlackStar Chrome 405w LED Grow Light FSF
16.00
16.00
54.00
54.00
100%
36.00
36.00
100%
BlackStar Chrome 720w LED Grow Light FSF
20.50
20.50
72.00
72.00
100%
48.00
48.00
100%
BlackStar 600 watt LED Grow Light UV
19.75
12.25
48.00
36.00
88%
?
BlackStar 900 watt Commercial Grade LED Grow Light UV
20.13
12.25
54.00
42.00
90%
?
LumiGrow Pro 650
17.00
10.00
120.00
120.00
94%
72
72
90%
LumiGrow Pro 325
11.00
10.00
120.00
120.00
99%
72
72
99%
DOMINATOR
35.00
8.50
48.00
48.00
45%
36.00
36.00
26%
DOMINATOR XL
36.00
12.00
60.00
60.00
60%
48.00
48.00
50%
DOMINATOR 2X
35.00
8.50
48.00
48.00
45%
36.00
36.00
26%
DOMINATOR 2X XL
36.00
12.00
60.00
60.00
60%
48.00
48.00
50%
Luminator
15.75
8.50
36.00
36.00
80%
24.00
24.00
70%
Luminator 2X
15.75
8.50
36.00
36.00
80%
24.00
24.00
70%
Vegetator
19.50
11.75
48.00
48.00
84%
36.00
36.00
78%
Vegetator 2X
19.50
11.75
60.00
60.00
87%
48.00
48.00
84%
Herbalvador
15.75
8.50
48.00
48.00
85%
36.00
36.00
80%
Herbalvador 2X
15.75
8.50
48.00
48.00
85%
36.00
36.00
80%
Mars II 400w LED Grow Light
11.50
11.50
30.00
30.00
100%
?
Mars II 700w LED Grow Light
15.00
15.00
36.00
36.00
100%
?
Mars II 900w LED Grow Light
15.00
15.00
42.00
42.00
100%
?
Mars II 1200w LED Grow Light
19.00
19.00
48.00
48.00
100%
?
Mars II 1600w LED Grow Light
23.00
23.00
50.40
50.40
100%
?
Reflector-48
12.00
12.00
24.00
24.00
100%
?
Reflector-96
23.00
10.00
36.00
24.00
96%
?
Reflector-144
28.00
10.00
48.00
24.00
75%
?
Reflector-192
24.00
21.00
48.00
48.00
94%
?
MarsPro 160LED Epistar-160
23.00
14.00
48.00
24.00
38%
?
MarsPro 320LED Epistar-320
23.00
23.00
48.00
48.00
100%
?
MarsPro Cree-128
23.00
13.00
48.00
24.00
42%
?
MarsPro Cree-256
23.00
21.00
48.00
48.00
96%
?
P150
19.00
5.00
54.00
42.00
95%
36.00
18.00
78%
P300
19.00
9.00
54.00
45.60
96%
36.00
24.00
92%
P450
19.00
11.00
54.00
48.00
96%
36.00
30.00
93%
P600
36.00
8.00
72.00
45.00
98%
60.00
24.00
67%
P900
36.00
12.00
72.00
48.00
100%
60.00
36.00
100%
P1200
36.00
19.00
72.00
66.00
83%
60.00
48.00
90%
P4-XML2
24.00
24.00
48.00
48.00
100%
36.00
36.00
100%
P9-XML2
28.00
28.00
60.00
60.00
100%
48.00
48.00
100%
MAX-600
25.13
15.13
48.00
48.00
79%
?
MAX-1200
25.13
15.13
48.00
48.00
79%
?
Illuminator 100W
12.00
12.00
48.00
48.00
100%
24.00
24.00
100%
Illuminator Jumbo 200W
15.00
15.00
60.00
60.00
100%
36.00
36.00
100%
Illuminator Commercial 400W
22.00
22.00
72.00
60.00
80%
48.00
48.00
100%
Mother Keeper 100W
11.50
11.50
?
?
300 Series 90° reflector
12.56
12.13
60.00
60.00
99%
36.00
36.00
99%
300 Series 120° reflector
12.56
12.13
48.00
48.00
99%
?
400 Series 60° reflector
14.56
12.56
48.00
48.00
96%
?
400 Series 90° reflector
14.56
12.56
96.00
96.00
98%
48.00
48.00
96%
400 Series 120° reflector
14.56
12.56
96.00
96.00
98%
60.00
60.00
97%
400+ Series 60° reflector
14.56
12.56
48.00
48.00
96%
?
400+ Series 90° reflector
14.56
12.56
96.00
96.00
98%
48.00
48.00
96%
400+ Series 120° reflector
14.56
12.56
96.00
96.00
98%
60.00
60.00
97%
M6
12.60
12.13
?
?
M9
19.21
19.21
?
?
M16
23.62
23.62
?
?

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