LED Buyers Guide

If you’ve read the LED section of our grow light guide, you’ll know that when you’re choosing an LED light, you’re at the mercy of unscrupulous vendors who take advantage of the confusion of various LED light specifications which are often misrepresented. The first thing you’ll see when choosing a light is the wattage. Simple right, this is just how many watts the light uses. Unfortunately that’s almost never accurate. When you see a wattage next to an LED light, it could mean one of three things:

    • Actual Power Draw – is how much power the light actually draws from the wall. This is the most useful piece of information. This is what people should be basing gram per watt yields off of, but often don’t. Unfortunately because this is the lowest of the three representations of wattage, vendors who are trying to sell their product almost never advertise this. If you’re lucky you’ll find it buried in the specifications, but even then, it’s usually inaccurate.
  • Combined LED Max Power Usage – is the max power the light can use in theory. So for instance, one of the most common arrangements is 100 x 3-watt LEDs, as seen on the right. This arrangement would have a combined LED max power usage of 300W. This is the most commonly advertised value used for wattage, however this is misleading because most of these 3-watt LEDs don’t actually use 3-watts. Each color of LED uses different amounts of power, so instead of giving the exact wattage for each individual light, they categorize them based on equivalent light output. Furthermore, manufacturers often run LEDs at ~40-50% power because this means less heat, which increases LED lifespan and efficiency. This means that an LED lights advertised as 300W with 100 x 3W LEDs have an actual power draw of ~120-150 watts.
  • HID/HPS Equivalency – is the wattage of the HID light this LED is supposed to replace. This is the highest number you can advertise for an LED, but it’s very misleading. For example, it’s fairly common for vendors to say a 300W LED (100 x 3W LED) is equivalent to a 1000W HPS lamp. If you’re lucky, that 300W LED actually uses about 150 watts whereas a 1000W HPS uses about 1020 watts. This means for a “300W” LED to be equivalent to a 1000W HPS, the yields would have to be 7x more grams per watt than the HPS. If that were true, everyone would have switched to LED lights by now. When measuring by actual power usage, LEDs tend to have ~20-100% higher yields, but never anywhere near 7x. If you want to know actual HID/HPS equivalency, take the actual power usage and multiply by ~1.2-1.8x depending on the quality of the LEDs. If you’re uncertain on the quality of the LEDs, we recommend estimating on the low end so you don’t end up with less light than you need.

In order to determine the actual power draw of an LED grow light, you need a little understanding of the individual LEDs used to build these things, so we compiled a list of the different types of LEDs used to make grow lights:


<1 Watt LEDs


5mm LEDs, as seen on the left, are among the most common LEDs. They are commonly used by hobbyists for various electronics projects. For grow lights however, they make a very poor choice. These LEDs consume about 0.03-0.1 watts each, meaning 1000 of them will only consume about 40 watts, making them expensive to manufacture grow lights out of and not very effective for growing cannabis. To reach the ~150 watt consumption used by the smallest LED panels, you’d need about 6000 of them, which on a panel with minimal spacing would be about 2×2 ft or 60×60 cm. If you see a light with thousands of individual LEDs with little spacing that is only advertised as ~100-300 watts, they might be using 5mm LEDs, which means it wont be an effective grow light.


SMD LEDs are the more common type of <1 watt LED. They’re usually rectangular or square in shape and come in long strips. They come in a variety of wattages and can actually be rated for over 1 watt, but very rarely do they actually consume more than 1 watt. Most SMD LEDs are rated for about 0.5 watts, and actually consume around 0.2 watts, however SMD LEDs used for grow lights are often much weaker than that. If you see a light with many individual LEDs, little spacing, and little space for cooling, it’s probably a light you want to stay away from.


1W & 3W LEDs


Anything above 1W is generally considered to be a “High Power LED.” High Powered LEDs are the best and most common LED in grow lights. Unfortunately the only way to tell 1W and 3W lights apart is the size of that tiny orange square in the middle of the light, which is what actually produces the light. The two metal prongs are the +/- power connections and the clear globe around it is the lens which determines its viewing angle. A wider viewing angle, say 140 degrees, would have a widespread light with less canopy penetration, but would allow for closer placement to the plants. A more focused viewing angle, say 90 degrees, which seems to be the popular viewing angle, allows for a more focused light that penetrates the canopy better, but can limit how close your lights can be.

If you count the LEDs on the panel and there are 100, then you know they’re 3W if it’s presented as a 300W light. Fortunately a 3W light only costs about 5% more than a 1W light, so there’s really no good reason for a manufacturer to misrepresent 1W lights as 3W. This is why 3W lights are the most commonly used LED. When in doubt, you can probably assume an LED grow light is using 3W LEDs.

5W & 10W LEDs


What you see on the left are 5W LED diodes. While 1W and 3W LED diodes do look similar to these, if you look closely you can see 4 of those little squares inside these 5W LEDs. Fitting those small chips together makes 5W lights more difficult and expensive to make, making them a significant step above 3W LEDs. Sometimes they’ll only have 2 of those chips, but always 2-4 for 5W LEDs. If you see a seller claiming to be selling 10W lights that look like these, chances are, it’s a lie. Although they can be made in this format, usually they’re a bit larger as they must fit about 9 of those small square chips inside.


To give you an idea of how much more heat 10W LEDs generate, we’ve displayed a 10W LED heatsink on the right. This is how much space is needed to radiate the heat from a 10W LED. Although the heat can be radiated someone vertically rather than out horizontally, this just shows how much extra space is required for cooling of 10W LEDs. If you see someone claiming to sell a light with 10W LEDs, check how close together the lights are and how thick the light is. Thicker lights means more space dedicated cooling, so the lights might be higher power. If you can, check how many chips are in the individual bulbs. When in doubt, you should assume that any LEDs that resemble these are most likely 3W LEDs unless you can make out multiple chips per LED, in which case it’s probably a 5W LED.


Chip on board (COB) LEDs


The next step up the food chain of LEDs are COB LEDs. Although it’s possible to make a 10W LED that resembles 1W and 3W LEDs, most 10W LEDs are COB LEDs. They usually come in the shape of a square, as shown on the left, but can come in other shapes. Much like 5W LEDs, you can see how much power an LED has based on the number of those small square chips on the board. For instance the 10W LED has 9 chips. If you look closely you can see 20 chips on the 20W LED, 30 chips on the 30W LED, and 100 chips on the 100W LEDs.

If you’ve looked into buying various LED lights, you’ve probably never seen these. But why? It’d make a lot of sense to just jam 20 colored 20W COB LEDs onto a panel, right? Although that’d be an easy solution in theory, there’s a problem with LEDs known as the efficiency droop. The efficiency droop describes how brightness, lifespan, and luminous efficiency, quantified by lumens per watt, decreases as current increases above 10mA. The high brightness LEDs used for grow lights use about 350mA, which is a compromise between brightness, efficiency, and lifespan. COB LEDs use more than this. 3W LEDs are the most common because the compromise is reasonable, and there’s enough space on a panel to fit hundreds of them without issue. If you happen upon an LED grow light that uses COB LEDs, just keep in mind that it’ll have lower brightness, efficiency, and lifespan.


Lumens per Watt

Another important thing to know when deciding on an LED grow light is what typical lumen per watt (lm/W) numbers are for various LEDs. While PAR is more important for plants, the lumens can still help you tell if a vendor is being honest. While white LEDs are capable of getting more than 100 lumens per watt with high power 350mA LEDs, more specific wavelengths of light, such as red or blue, aren’t capable of such high efficiencies. Leaders in the LED industry are getting about 35-39 lm/W for red LEDs and 25-37 lm/W for blue LEDs. So if you see a vendor claiming to sell a 300W light consisting mostly of red and blue that gives off 15000 lumens (50 lm/W), that should be a red flag, especially considering the actual power draw for a 300W LED is likely to be closer to 150W.


About LED brands


Often the company who makes the LEDs in the light isn’t stated at all, but if it is, the two most commonly used are Cree, from the US, and Epistar, from Taiwan. Both are great LED manufacturers, but Cree has the best reputation, plus a few thousand patents to back it up. The problem with Epistar is that they sometimes are paid for their name. As a result, there are tons of unregulated LEDs labeled Epistar, some of which aren’t even paying Epistar. So while Epistar is a great LED manufacturer, you can’t really trust that an LED labeled as Epistar is actually made by Epistar unless they have some kind of certification that Epistar can verify.

There are numerous benefits to having LEDs made by a reputable manufacturer. First, there’s binning. LED lights from Cree are manufactured with a maximum intensity variance of 10%. The LEDs outside this range are discarded. This means all Cree LEDs are going to be about the same brightness. Other factors that are closely controlled by reputable LED manufacturers are total lumens, efficiency, CRI (color accuracy), lifespan, power factor, and light spread.


Choosing a Grow Light – Made in USA or China?


Now that you have a bit more knowledge of how LED grow lights are made, it’s time to actually choose a grow light. So we’ve talked about all of the benefits of using a reputable manufacturer like Cree, so how important is it that our LEDs are made by Cree? Well that’s a matter of opinion, but more importantly, budget. One of the biggest knocks against LED grow lights is the cost.

Let’s compare an American made light using Cree and Bridgelux LEDs with a Chinese made light using Epistar LEDs. For the American light, let’s consider this $950 900W LED grow light (557W actual power consumption) by PlatinumLED, a popular American brand. For the Chinese light, let’s consider this $310 2-pack of 600W LED grow lights (2 x 278W = 556W actual power consumption) by Mars Hydro, a decent Chinese brand. This is a great example comparison because if you were deciding simply based on the title, you’d think the Mars Hydro lights were using more power. Fortunately Mars Hydro is very forthright and includes Actual Power Consumpion in the title of the listing. PlatinumLED doesn’t even go that far to advertise actual power consumption, although they do include it in the specs. When you can get something Chinese made that looks about equal it makes you wonder if it’s really worth paying three times more for the benefits of an American made, Cree & Brigelux LED powered light.

Before we continue, we need to point out that one of the most important reasons to pick a reputable grow light manufacturer is for safety reasons. Although grow lights are made all over the world where certification standards are different, when you buy a grow light you should make sure it has some safety certification (e.g. ETL, UL, CSA or BEAB) so you can be certain that it wont be a fire risk. You’ll be able to verify most safety certifications online. Many Chinese made grow lights aren’t certified at all, so you should be extra careful with Chinese manufacturers. For our comparison we’ve chosen a Chinese brand, Mars Hydro, that has real safety certifications.

So let’s go down the list and consider the things we risk by choosing the cheaper light:

  • Brightness – When we choose non-Cree LEDs like in the Mars Hydro light, we run the risk that the brightness from 556 watts will be less with non-Cree lights. This can be remedied by using another smaller light, for instance this $80 300W LED light (132W actual power consumption) by Mars Hydro. Although the brightness variance is going to be greater with Chinese LEDs, adding 132W will easily make up that difference, and probably more. The actual difference can be measured with a PAR meter if you have one.
  • Efficiency – related to brightness, since we have to add some watts, we’ll have to pay a little more in electricity. Once again, this difference probably isn’t enough to make up a 3x price increase. Even still, it is worth keeping in mind that in the long run you’ll be paying less money in electricity with most American made lights.
  • CRI / Color Accuracy – With Chinese made LEDs, the color may not be exactly the spectrum you’re expecting. A less perfectly targeted spectrum will result in lower Photosynthetically Active Radiation (PAR), or light that the plant actually uses. Even still, if you add the 132W we recommended, you’ll more than make up for the potential PAR lost without coming anywhere near the cost of the PlatinumLED light.
  • Lifespan – This is where the differences start to accumulate. A Chinese made LED is probably going to have a shorter lifespan. Sudden failure in LEDs is rare, so lifespan is usually expressed in L70 or L50, which is the number of hours before the light is working at 70% or 50% efficiency respectively. Although efficiency will likely drop faster with Chinese made lights, it’s not going to be hugely significant, at most the lifespan difference will likely be 5-25% different. Combined potential higher electricity costs, it starts to add up, but does it add up to making it worth paying 4x as much for an American made, Cree-powered LED grow light? That’s for you to decide.

If you recount the efficiency droop we talked about earlier, you’ll know that higher power per LED results in lower brightness, efficiency, and lifespan. Since the actual vs max power consumption of the Mars Hydro lights (556 / 1200 = 46.3%) is lower than actual vs max power consumption for the PlatinumLED light (557/900 = 61.9%), the Chinese LEDs actually have a brightness, efficiency, and lifespan advantage in this aspect. On the other hand, PlatinumLED uses 300 x 3W LEDs, whereas Mars Hydro uses 240 x 5W LEDs, and using the 3W LEDs gives PlatinumLED a bigger advantage in that aspect. Combined with that and the manufacturing precision and binning by American LED manufacturers means that the PlatinumLED LEDs most likely have better brightness, efficiency, and lifespan.

At the end of the day, we recommend everyone who can afford it to use American made lights, especially if you’re growing to sell. The cost of the light, even American lights, is dwarfed when compared to the value of the cannabis grown with that light. Aside from supporting the US capitalist economy over the Chinese state-run economy, there are plenty of functional reasons that American LED grow lights tend to be better, the most important of which if you’re growing to sell is their lifespan. We showed you an example of a respectable Chinese brand here, but don’t be fooled, there are plenty of Chinese brands that appear to be forthright and give you all the specs, such as actual power consumption, but often they are outright lying. Quite possibly the best reason to buy an American made light is that you don’t have to deal with all the nonsense this page has talked about. With most American LED manufacturers you can just buy a light and trust that it will do the job the vendor tells you it can do. While we recommend buying American made lights, we also realize that not everybody has $1000 to spend on a light, which is why we made this guide. If you’re a savvy buyer, you can almost always find a Chinese made grow light that is much, much more budget friendly overall.

If you do decide to go with a Chinese LED grow light, make sure you do the following:

  1. Count the LEDs on the light
  2. Compare the number of LEDs on the light to the wattage the light is advertised as. If it has 120 LEDs and is being advertised as a 600W, then you’ll know it is using 5W LEDs. If it has 100 LEDs and is being advertised as 1000W, then those lights should be 10W lights. Based on how they look and what you’ve read here, does that seem realistic?
  3. Consider actual power consumption. Ideally, the vendor will tell you actual power consumption, but not often. If a light uses 120 5W LEDs, then it’s max power usage is 600W, so realistically it probably has an actual power consumption of 300W or less. If you’re uncertain, we recommend buying an electricity usage meter, such as the Kill-A-Watt, and measure the actual usage yourself. Ask the vendor beforehand if you can return the light if it’s not reasonably close to what they advertised or what you expected.
  4. Consider lumens per watt and lux/PAR per watt. If they are advertising a certain number of lumens, check if that’s realistic. If you’re uncertain what’s realistic, check out the specs of some American-made lights and make sure it isn’t higher than what they’re advertising. Be careful when comparing PAR/lux, as they are dependent upon the viewing angle of the LEDs, most of which are 90 degrees, and the distance that they’re measured at.
  5. Consider cooling. If the light is using 5W LEDs, the LEDs should be spaced further and/or the grow light should be thicker to make room for heatsinks and fans. If a light is claiming to use 5W LEDs you should see more space dedicated to cooling compared with lights using 3W LEDs.
  6. Check spectrum coverage. While red and blue should make up the majority of the lights used, there should be more than just two colors, including multiple reds, white, and infared. This is to make sure that your plants don’t end up with any nutrient deficiencies.
  7. Compare to similar lights. Pretty much any light of similar power, check the dimensions, especially thickness and weight if provided. If specifications aren’t provided exactly, just decipher as much as you can from the pictures.
  8. Look for a safety certification. Any certification is better than no certification. If they don’t mention one ask for it. We recommend against buying any light without any certification because there are definitely Chinese grow light manufacturers out there that do have the certifications, so there’s no excuse for not having them.
  9. Ask Questions. If you can’t verify the type of LEDs used, ask for close-ups. If you don’t see a certification, ask for one. If actual power consumption or light efficiency doesn’t make sense, ask about it. If you’re doubtful about what you’ll receive, ask for some guarantee or the ability to return it. Good vendors will be responsive to questions. If you ask questions and don’t get good answers, you should look somewhere else. If you can’t get all the information you need to make an informed purchase, you probably shouldn’t make that purchase at all. However there is a difference between an unresponsive vendor and communication difficulties brought on by a language barrier, so at least be patient to make sure they understand the questions you’re asking if you’re not asking in Chinese.

Hopefully this is enough to help you determine what kind of LED light you want to buy. In our opinion, the only Chinese manufacturer that we can recommend wholeheartedly is Mars Hydro, so that’s a good starting point if you’re not sure where to start. They have very competitive prices on Amazon, as referenced in this post. Do keep in mind however that even though they have our recommendation, you should question their lights just as you would other Chinese grow lights. They even have Cree-powered, USA-made lights (e.g. this 600W Light) at competitive prices if that’s what you’re looking for. A big part of the reason we recommend Mars Hydro is because they have good videos comparing their lights to counterfeits on their youtube channel, where they explain all the differences and show their lights read with voltage and PAR meters.