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Full investigation on CFLs lumen output vs wattage vs price


New Member
ok so i have been craving an upgrade to my grow, but first thing i need to settle on is my light. i will be growing in a 1x1 area. yes very small. i was contiplating getting a 100w MH. but decided not to for the money would not be efficiently spent. instead i will settle on multiple cfls

my goal is above 10,000 lumens.

i read somewhere of someone getting 7000 lumens for a 100w cfl. that is really good. but since i cannot find that bulb i am doin my own research. small bulbs put out too little per watt, and super huge ones do to. but larger bulbs cost more. so where is the happy medium? taking into account money spent at the counter and on teh electric bill what is the right way to go?

compairing products with their lumens output i have found that

1,700 lumens @ 26 watts = 52.17 lumens per watt.
3,000 lumens @ 40 watts = 75 lumens per watt.
9,200 lumens @ 150 watts = 61.33 lumens per watt.

clearly the biggest bang for the buck lookd like the 40 watt light. but after writing this i see it isnt. to demonstrate my point, lets go with a hypothetical set up, it is needed min 5,000 lumens per sq foot, and 10,000 lumens is what the sun puts out. so a good set up should have a bit more than 10,000 or around there. per foot. but for the sake of compairson...

lets use 18,000 lumens as our minimum goal so that the math adds up right and we have a comon denominator

11 x 26 watt = 18,700 lumens
6 x 40 watt = 18,000 lumens
2 x 150 watt = 18,400 lumens

now lets put some money value here.
using generalized prices

26 watt = $5 --> 1700 lumens/$5 340 lumens per dolar
40 watt = $35 --> 3000 lumens/$34 88.2 lumens per dollar
150 watt = $80 --> 9200 lumens/$80 115 lumens per dollar

so now lets apply the prices if we were to build our hypothetical 18,000 lumen grow box.

11 x $5 = $55
6 x $34 = $204
2 x $80 = $160

now that was the prices you pay up front at the check out line for the lights. now lets see how they will cost you when your in a 24 hour veg cycle for 4 week, or more specifically 31 days.
11 x 26w = 286w total
6 x 40w = 240w total
2 x 150w = 300w total

now lets pay for these lights to run for a straight month in a 24 hour veg cycle

286w total = $25.53 added to the bill
240w total = $21.53 added to the bill
300w total = $26.78 added to the bill

so the total you are paying for is

55+25.53= $80.53 for 18,700 lumens
204+21.53= $225.53 for 18,000 lumens
160+26.78 = $186.53 for 18,400 lumens

humm...... now this is where it gets subjective. for 80 bucks you can have 18,400 lumens from the little 26 watters. but you need 11 of them. it is going to be difficult to manage to make that happen. but if what you're aiming for is cheapest light source i think it is the 26w bulbs. so if you dont mind the hard work setting all that up then i gues these are the lights for you. I think the catch was that although the 40 watt does make more lumens to the watt, it is completely overpriced. and the overal difference in wattage is not important on the long run in the bill nor is it important on the short run, when u pay at cash register.

now to pack them together i dont know what kind of heat we are dealing with. i dont have any heat values. nor do i have size values. i bet it gets difficult to get 11 lights in a square foot above a plant.

Now please tell me what you think, point out flaws and all sorts. i plan on redoing this calculation. there has to be something wrong no?
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New Member
Add on: going by the pricing of the $5 26w bulb, a 40w bulb is overpriced

if every bulb was supposed to go by the prices per wat like a 26w, then a 40w should be a bit over 10$ because 40 is like the double of 20.

so if 26w\5$ then 40w\should be $7.69!!!!!!! what a rape on the pricing!!
and if it was the other way around 40w/34$ then 26w would cost $22.10!! see what i mean?


New Member
When i bought my 42 watt cfl lights from wallymart they were $16 each. They have a wider range of light spectrums available too when compared to the giant bulbs. Let me tell ya ahead of time, in that small a space heat will get above 100 degrees almost instantly. You will need a large and efficient exhaust fan, one that moves massive amounts of air to keep temps down. I think it will be nearly impossibe to fit 11 bulbs in 1 sq. ft. I fit 11 on a board that was 1x2 and even then it was a tight fit.

Also, accidents happen. If you got the 150 watt bulbs and 1 dropped and broke, you're out half your lumens and have to spend $$$ to replace it. Don't forget that the giant bulbs require special sockets to screw into to handle the heat and that adds to the setup costs.

I see the middleground cfl's as optimal. I did all that math myself last year and thats the conclusion I came to.


New Member
When i bought my 42 watt cfl lights from wallymart they were $16 each. They have a wider range of light spectrums available too when compared to the giant bulbs. Let me tell ya ahead of time, in that small a space heat will get above 100 degrees almost instantly. You will need a large and efficient exhaust fan, one that moves massive amounts of air to keep temps down. I think it will be nearly impossibe to fit 11 bulbs in 1 sq. ft. I fit 11 on a board that was 1x2 and even then it was a tight fit.

Also, accidents happen. If you got the 150 watt bulbs and 1 dropped and broke, you're out half your lumens and have to spend $$$ to replace it. Don't forget that the giant bulbs require special sockets to screw into to handle the heat and that adds to the setup costs.

I see the middleground cfl's as optimal. I did all that math myself last year and thats the conclusion I came to.

thnks for the feedback!

and 16 sounds like a steal. i have to check wally sometime and get more prices, these prices are just some i found on the net, and i bet they can be beat real quick.

and i have no intension to build this set up, it was hypothetical. but 11 lights putting out 18000 lumens would seem good on a 1ft by 2-2.5ft board.

and like i said, heat was not put into the equation, but i bet it would be horrible!!!


New Member
This is how much light you get with that many bulbs.


To control the heat i eventually went with this cause i had it laying around and it worked good.



New Member
you are missing a couple of bulbs in that grouping

65 watt cfl aroud 4000-5500 lumens

85 watt cfl around 7500 lumens

i saw at lowes the 65 watt cfls two prices 17.00$

85 watt mail order topbulb 25.00 each plus shipping
you could probably do two lamp sockets at the top of 2 opposing walls so bulbs are side by side but reversed like 2 batterys in a old tape walkman etc but effectively your whole ceiling is emitting light

saw some threads of awesome microgrow 5x7 inch footprint grow area speaker type with 70 watt HPS
[icmag; microRU; sorry moderator but i don't remember a better mircro grow here to send them to ]

cooling saw an awesome looking mini squirrelcage blower 12 volt for computers [ evercool pcac]


New Member
Wow Zolar you a really good at finding these deals. I went to wallmart and found some cheap cfls.... Muchhhhh more efficient that online bulbs for some reason. I was confused as to why buying online is so overpriced? But anyhow I saw a 65w cfl from a brinks security outdoor light, but it was some $50 because it was with a separate ballast. but it claimed 7000 lumens. Now these ordered 85watt sound goodl. From what I have seen 85w are hard to find in 6500k, but quite easy to find in reder spectrums. Getting both would be ideal. But is it worth it to buy 170w worth of cfls rather than a small HPS or MH?

I am building a friend a les lumnous box than mine, and it will be 3x1x1 and host a small scrog I went shopping with him and settled for 4 26w @ 1600 lumens each. Came out to bout 14$

As a reflector we will use a tin pan we got for 1.59$

But Q
Is a separate ballast bulb good? It seems more energy efficient while putting out lots of lumens


New Member
how tall is that 1x1 space

you should be able to find the 65 watt bulbs for about 20 $ in stores am checking lumen #s off tech data bulb place trick is finding a bulb with out having to buy a security light too with it

just checked topbulb tubular 65 watt not spiral cfl 4100 lumen 5000k 15.99

spiral 65 watt 5000k 27 $ 2700 k 22 $ 4100 lumens

i know i saw both types of 65 watt at lowes

but as for a small space i use 2 42 watters in a converted
rounded top fridge grow area is 15 inch x 21 inch by not quite 30 inch high this works ok but i will be getting 65 watters
probably tubular longer light emitting tubes actually exposed to plant than spiral
just checked that fridge cab with gossen luna pro light meter [ansel adams used one of these but he preferred a weston meter that read out in footcandles directly] 42 watt and 27 watt
1,5 ft by 2 ft space about 600-650 lumens or footcandles and 6000 lux [lux = lumen/meter2] 42 watt cfl on spec sheet 2800
lumens this reading was between the bulbs about 4 inches down a local has everything dept store old fashioned general store had 125 or 130 anniversery couple years ago think they are true value hrdware dealer had 65 watt bulbs for 23 $ but you need to remember a 65 watt draw is equivelant to a 300 watt in old style incandesent for cfls its the lumen output and color temp you want cause the packages arte sneaky with the big labeling numbers usually the size of old style bulbs they replace and not watts they draw and lumen output but any how the generalstore place can order the higher watt cfls and have them local in 2-4 days proibably any hradware store can do so for you [thats probably why they're still in business after 100 plus years plus in center of town from before when stores had to build parking lots for cars to meet codes].... but 2 65 watt draw 300 watt equivilent cfls
will work fine for a little space like you are describing that should be less than 50 $ maybe less than 40 in you can find the cheaper tubular instead of spiral if that space is taller than 2ft you might want to put 2 or 4 2 ft regular flouro tube units on the walls 2 should work fine in 1x1 ft this would give you a micro phototron unit i think you can the whole fixture with bulb around 15-20 $ if you have a really good airflow you could do a 70 watt HPS security light 75$ at lowes priced them this week showing a high school buddy what lights he could do for his space now that the kid and grandkids moved out
and plants won't get botherted...... hope some of this makes you options make more sense as to why may even ressurect first cab 32 inch talll white foot square bookcase no middle shelves 1 lamp socket screwed to underside top shelf uses 42 or 65 wattt draw cfl great for 1 plant u assemble furniture walmart etc


i've been through this at length many times since i started!! ive got lots of info as far as the formulas and physics go if you want, let me know.

here's just a small piece of what i got relevant to you...
it's long sorry bear with me..;)

they make those cfl's in 105w@7600 lum through 200w@12,000 lum (actual power consumption with lumens as initial rating - all lights have 'initial' and 'mean' lumen ratings) and they are fairly pricey $69 - $150, which is more than my 1000 watt mh bulbs that run $59 and get 105,000 lumens.

the cfl's have very distinct drawbacks compared to hid's already at low power ranges that are magnified w/these high power cfl's as far as i can tell.

1st is yea you can use these in lamps and such, but only w/a 'mogul' type adapter to fit it to the 'medium' base of the sockets, $10 - $30 for those.

2nd is these are beast's!! 16" long for the 105wt and 18" for both 150 and 200 watts.!!! and thats not with the 3" adapter plus they are 5-6" across the base.

3rd and most important for growing a tall, light hungry weed plant is "artificial light fades fast". For every foot a ray of light travels, it loses about one quarter of its power. so for example the 105 Watt cfl @ 7600 lumen has over 700 foot-candles right next to the bulb but:

about 525 foot-candles at 1 foot away from the bulb,
about 394 foot-candles at 2 feet away from the bulb,
about 295 foot-candles at 3 feet away from the bulb,
about 221 foot-candles at 4 feet away from the bulb,
about 140 foot-candles at 5 feet away from the bulb.

with cfl's i do the lux calc's in cubic feet basically. adding more light for each 1 foot tall the plant gets as well. the hid light is better for growing a tall plants like weed cause it penetrates better. 1 cfl of any size just does not have enough power to drive the growth a weed plant needs. so you have to use more of them, lots more. and they have to be 2-5 inches from your plants at all times.

efficacy is a term used to describe the efficiency of a lighting product. this is measured in LPW, or lumens per watt. to determine the efficacy of a lamp, divide the lumen output of the lamp by the watts consumed.

for example,
105wt/7600lum cfl - lpw 72
200wt/12,000lum cfl - lpw 60
42wt/2700lum cfl - lpw 64
26wt/1600lum cfl - lpw 63
now for hid's
1000wt/105,000lum mh - lpw 105
1000wt/150,000lum hps - lpw 150
500wt/55,000lum hps - lpw 110

i seen y'all going over that one too, and debating the cost of lot's of cfl's that need lots of plugin's and extra stuff that will double the actual cost of your build, versus a single hid of the same price.

this might help i hope, but keep in mind i have had a successful cfl grow - '4 random heavy hitters' in my signature line, so you can look and see if that's the way to go. i did however buy my stuff a few here and there and wound up w/over 500wts of cfl's hanging over my plants w/my biggest bulb a 42wt. but at the same time me, electricians, and even folks from this site was aware of the actual fire danger that my cfl rig was capable of, you wanna keep your grow safe, trust me!

keep it simple, if you want big yields or more than a couple plants you need them lumens. and watts are a side effect of lumens. i dont see how saving energy and weed growing ever wind up in the same sentence. you need the most of both you can support! you could save by buying efficient fans and other grow peripherals and not using the other stuff in the house as much if that's your goal. don't skimp on your lights. small rooms/grows with only 1-2 plants will still be awesome for sure with a big setup, but using a good reflective covering everywhere and a few well placed cfl's will get you smoking!! i know a guy that got a 30+ gram cola with 3-42wt and 2-26wt cfl's in just 75-80 days!

those big cfl's aint worth it to me! a lot of 42wt red's for flower and 26wt blue's for veg duty is really the only way to go cfl. those are $8-10 for a 42 or a pack of 26's at a wal-mart. hid's not cfl's if you wanna spend more than $30 on a bulb!! plus with more of the smaller bulbs you'll get the added benefit of optimal placement. i still have my cfl's waiting to go under the canopy when needed to help out the hid up top.

hope that helped, if not, sorry for the novel!!!! :cool027:


New Member
sorry to sorta highjack but you seem to know abit about cfl's. i found this 100w light Aussieponics! Australias Own Hydroponic Control Gear! - Grow Lush Energy Saver 100 Watt 6400K Lamp (Powered by CubeCart) and emailed him asking its lumen output he said it was 10,000 average. my question is i noticed u said u couldn't find any lights like this so i was wondering if i was being lied to? any ideas?

sorry i havent checked this post in a while, but since i have done allll that research i constantly find more efficient lights. but however, the site looks very scammy. it doesnt have a professional look to it at all and while describing the light they say alot, but never back any of it up with real numbers. im sorry to say but i would not buy from them. look up the bulb on different places and try to get real facts and then determine where you would get it after you see it is a good buy.

happy growing!


New Member
I think cfl's are better suites to being support lights. Sorry to state the obvious, but if you are going on light vs power vs price efficiency, a 600 watt HPS really takes the cake. I mean the awesome yield the plants will achieve will more than justify the higher price tag. I think cfl's should be added to get extra light to lower buds of a large plant.


New Member
nbk380. thankyou for your post. i have a plant in veg with 4 27 wat cfls, that keeps getting another week after week added on. but i dont care about it because its just vegging, and that cant do any harm.

buy you have proven a great point. light intensity. the firehose example really hit home. i know its cliche to bash cfls over hps grows, but i am slowly but shurly getting it now and will probably be going for a hps and a diy cool tube, it seems to make so much more sense.

and also, the info i used for my compairisons keep getting disproved and i keep finding more efficient lights at wall mart every time i go.

using my cfl's they are never more than 5 inches away from the lady. although i am not losing light due to distance, i see there are little bushy wanabee branches who havent grown an inch because they are in the shadow of the larger fan leaves. this definately shows how little the cfl rays penetrate through to them.

happy growing! pce


New Member
yea i was looking at teh 150Ws because i realized there are hardly any 100w lol. but i think i will be happy with one. and 150 is hardly any power consumption, not noticable at all.

one time i found a light in the attic that had been on for moooonths! and it was a stupid incadecent 150w! but no one noticed it on the bill so, jsut as a proof of concept it hadly is power consuming.

for under $100 you say? i was looking at some good blubs and such, by hortilux and sun systems. they look great and super effecient lumens to watt ratio. i am hopeing someone posts in my other thread asking for suggestions on brands and models of hps lights.


New Member
I'm a true believer in cfl's. There's no reason to "up" your power bill (In a Small Grow) by using MH. Plus the temps are much lower so closer application to the plants. I've gotten excellent vegetative results with one of these:

200 Watt CFL - 600 W Equal - Full Spectrum 5000K - Spring Lamp - Energy Miser FE-IIIB-200W-50K Light Bulb

There's also a mogul adapter, which allows to use a regular medium bulb base here:

Medium to Mogul Enlarger Socket - 1.75 in. Extension - Satco 92-414 Light Bulb

Anyone else used one?

-Happy Growing-


New Member
That looks like a great bulb and indeed, but if you are going to be using 200 watts to vegetate, which is most likely 18/6 hours your bill will still get run up, and your only getting 10,000 lumens in compairison with a 150w MH or HPS light that produces 16,000 lumens.

Cfls win the heat factor though. That is just obvious.

But I'm feeling like I'm getting swayed everytime I look into it. Also for $70 you can get an HID.

Happy growing and good conversation. anyone else want to give an opponio?


hi all thought i'd chime in with my two cents,
i'm using a 125 watt cfl from hydrofarm with the hood and all cost 119.95,replaced four 100 watt bulbs in the house with 14 watt cfl's just to help the light bill out.
heat is not a problem they are not hot.
check out my journal in the grow room,i have used this bulb before for veg with very good results,never for bud so this is a first time here for that, but i have done a grow using shop lights from home depot they were just regular shop lites from start to finish and it was some of the tightest bud i've ever grown. like i said just my two cents.
good luck what ever you choose to use.
i'll post some pics of the shop lite bud in my journal.see ya there


New Member
I think cfl's are good for sprouting, clones and early veg; after your plants get older than a few months, they need the flowering spectrum of hps.
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