light level selection

For a 120×120 cm tent you’ll want around 450–500 W of quality full-spectrum LED to get solid coverage and dense buds Your single 240 W light can work, but it’ll be on the lower side for 6 autos you’ll likely see lighter yields on the edges. If possible, add a second 200–250 W panel or run 4 plants instead for optimal results. Aim for around 700–900 µmol/m²/s PPFD during flower for best performance

go by umol/s PAR production, assuming the spec sheets are accurate, which is not always the case. It's a far better way than watts per sq ft, because efficacy varies. you'll see lights anywhre from 2-3ish umol/J efficacy. This means 920umol/s will either require 460watts or 306.67watts. 153.33 watt difference can add up and often makes buying the more efficeous, more expensive LED cheaper in the long run. This is a basic break-even pointn calculation and depends on the cost of kw-h in your area. .15kw x 18h is 2.7kw-h per day x 30 and 81/month and at my local rate that's about 16 dollars saved every month. 16x12 - 192 USD per year. These lights will last 7-8 years before they dim to 90% of original brightness. That's 1344 dollars saved over 7 years. This would be an extreme case.. probably won't buy a 3.0umol/J light and 2.0umol/J is a really, really shitty light, lol. Efficacy will not effect yield on its own. Less efficeous lights will produce more heat -- may be good or bad depending on context. Efficacy can make a more expensivie light a much better financial decision. Know your maths! This is all common sense stuff. Anyone that doesn't appreciate an education should not contact me via DM. i won't hold someone's hand through this stuff if you were too much of a wasteoid in school, BWAHAHA. Seriously, it's low level algebra and common sense.

autos are variable size, so i'll just assume you'll make it fit the 4x4 (120x120). 16 sq ft running 18hours a day will need roughly 920 umol/s PAR produced from a light -- this assumes distribution of said light is proper for a 4x4, so apply some common sense. Any grow light that produces that much will do a great job. May even need to dim it 5-10%, but it'll be safely near max DLI for ambient CO2. If you want to keep open the possiblity to grow photoperiods, you have to do these calculations for 12 hours of operation. It is inversely proportional, so 12h vs 18 needs 150% of the power. 1.5 * 920 = 1380 umol/S PAR. The DLI that results from each of these suggestions is the same. This is all worked backward from 38-39 DLI calculated from full power of the light.. in reality, the plants will get less than that and that's built into these suggestions. Fairly well-controlled temp and rh will be required to hit these levels of DLI and typical ambient CO2. Relative to existing LED grow lights means the hanging distances are roughly similar. A measurement at your canopy level would be a better metric to use in the future if dynamics of grow lights change. more power from greater distance will have better penetration -- retain higher levesl further away from the lgiht.. .this is due to light spreading out in a way that adheres to the inverse square law and not an opinion or bro-science. So, there are things to consider when choosing umol/s PAR power and distance from canopy. You can run fewer watts and much closer, but then you don't get as much light deeper into canopy. This is great in early vege, but maybe not optimal for fully grown plants. read the wiki on DLI. It's super easy stuff to comprehend and apply. (daily light integral) .. for the most part that is the key, but as i just stated power and distance is a variable too. You need to waste more electricity from further away and up to a point that will be a benefit. LED are usually best ~18" away. Reduces hotspot in center and improves sides/corners. With a tiny plant in early vege, go ahead and amp down, get it nice and close -- use a klux meter or quantum meter and you can ensure your light at canopy is at the proper level at the lower percentage of power. when it is closer, the light has not spread out as much, so you can use less electricity and provide same DLI. From all that, you should be able to extrapolate or deduce anything you need to do with a light.

aim for DLI, but if you can't calculate that as its multiple lights and their is no PPFD map, I'd aim for around 30-50w per square foot. 120.120 is about 4x4 feet. 4x4=16 ft2 - square feet. 240w/16ft2=15w/ft2 so you need 2-4x more lighting power. Maybe post the light you plan on using other might have better advice. I;d say stick to the same model and just doubble it up vs one lightat 240w and another at 200 or 300

I would say 500watt to 800watt will do you really well I’m sure there are so E smaller lights designed for your tent but more light the better