How-To Geek

Pick the Right CFL Lightbulb Based on Watt Rating

After buying 75w and 100w bulbs all your life, it might be difficult to make the jump to low-watt CFL bulbs that top out at around 45w–use this handy chart to pick the right bulb.

Courtesy of, the above chart helps you make the translation between the regular watt ratings your used to and the new ratings on CFL bulbs. If you need a 150w reading bulb, for example, what you really need is a bulb that puts out a nice healthy 2,600 lumens or so. To make sure you’re getting that kind of output, look for a CFL bulb in the 40-45w range and then, of course, double check the documentation on the box.


Jason Fitzpatrick is a warranty-voiding DIYer who spends his days cracking opening cases and wrestling with code so you don't have to. If it can be modded, optimized, repurposed, or torn apart for fun he's interested (and probably already at the workbench taking it apart). You can follow him on if you'd like.

  • Published 02/24/12

Comments (13)

  1. RonV

    I am still holding out for inexpensive dimming LED light bulbs. Yes for the first 200 hours CFL put out the rated LUMENS after that they get dimmer and dimmer. I would say in the last two years that CFL’s color spectrum has gotten much batter that the blue green light they used to emit.

  2. LadyFitzgerald

    Wattage ratings aren’t an accurate guide of CFL equivalency to incandescent lamps. I’ve found it necessary to go up one rating to get as bright a light; for example, a 75w equivalent CFL to get the same brightness as a 60w incandescent. While 18w for the CFL that claims to be as bright as a 75w incandescent but is only a hair brighter than a 60w incandescent is still a considerable power savings over a 60w incandescent, not to mention much longer lamp life and noticeably cooler operation, it’s galling that manufacturers feel they have to lie about their ratings. I’ve also found that there are many brands of CFLs that are just garbage, mostly expiring long before the advertised lifespan (of course, they get away with that because they claim to last “up to” a certain lifespan; more deceptive advertising).

    Oddly enough, the major brands do as bad as many Chinese knockoffs. I’ve found the Ecobulbs, made in China (of all places) for the Canadian company, Feit Electric Co. performed best of all the ones I’ve tried (and I tried a lot of them) and give me the most bank for my buck (lowest cost per hour of life for those of you on the other side of the pond). They fire in a reasonal amount of time with an initial brightness greater than most other brands (the difference between initial brightness and full brightness is unnoticeable unless compared side by side) and are less sensitive to lower temperatures than most (lower temperatures will cause dimmer initial brightness until the CFL can warm up and ofrten limits ultimate brightness). I have to use a GE brand CFL that is designed to work in smaller fixtures so it will fit a fixture in my hallway and it takes longer to both fire and to reach full brightness. I’m about ready to yank that fixture and replace it with a larger one (as soon as I find one that matches other ceiling fixtures in the area without being overly huge; yes, I’m fussy).

    I’ve also found the CFLs that have an additional envelope around them so they look more like an incandescent in open bottomed fixtures are all garbage, no matter who makes them. Their initial brightness is equivalent to a candle flame and they take 5-10 minutes to reach full brightness.

  3. LadyFitzgerald

    @ RonV. The Ecobulb CFLs I use do not dim much over their lifespan. I can pop a new one in alongside older ones in a fixture and the difference is barely noticeable.

    Not being dimmable is one reason I still use halogens in my outside fixtures. That and instant firing with full brightness in temperatures below room temperature. CFLs will work ok outdoors in the climate I live in (Tempe, AZ; it infrequently gets below freezing) as long the lamp is in an enclosed fixture but they can take half an hour to get to full brightness when it’s really cool, not a problem for a lamp on a photocell that comes on just before dark and stays on all night but worthless for a porch lamp you want to come on the instant you hit the switch.

  4. LadyFitzgerald

    It’s going to be a while before LEDs will be dimable and still be as cost effective as CFLs (CFLs still have the edge over nondimmable LEDs but they are coming along fast). Since the lighting circuits in RVs are 12v, many RVers are converting to 12v LEDs to save on energy and reduce heat output. Some of those are dimmable. It is difficult, however, to find good quality, economical LEDs with acceptable light output (both in lumens and Kelvin temperature) and no RFI because of all the garbage flooding the market right now. The good ones are still expensive.

    New lighting technology, such as CFLs and LEDs, has been concentrating mostly on replacing incandescents in existing fixtures. What will really make LEDs take off is when people start installing LED lighting fixtures that run on separate, regulated low voltage circuits instead of using lamps that have voltage regulation in each lamp. The individual lamps will be less expensive, RFI will be less of a problem, and dimming will be less expensive and easier to achieve. It is not likely to happen with existing homes but new construction is already strting to see some of that happening, the biggest obstacle being code restrictions.

  5. Tony

    It’s not “your used to” (CFL Lightbulbs), it should be “you’re used to.” Small point but annoying to your readers. If “you’re” going to make the effort to publish “your” work, at least get the grammar right.

    Grrrrrrr. . . . .

  6. steve823

    Ever notice the government forbids anything with mercury in it because it’s bad for your health? Then they push the CFLs on you and call it green. They just don’t mention while they’re doing that that the CFLs contain mercury. But that’s ok if it furthers their agenda. By now you must be wondering just what their agenda is, huh? One day while working up on a ladder and concentrating on what I was doing I thrust my forehead into and broke a CFL. I’m still wondering what happened to the mercury in that lamp. I’m soooo glad the government is looking after my well being.

  7. Donnie

    If you are conserned about cost of electricity, go to the LED bulbs. They operate only at four watts and don’t have to worry about mercury. They aren’t as bright as incondecient bulbs but you don’t need bright bulbs in all places. Really bright bulbs are needed only for reading. The cost of LED bulbs is high now but coming down as more people are using them. I’m slowly replacing mine and I can tell the difference in the power bill. Another big help is the installation of timer on hot water tank.

  8. Wayne

    Already switching to the more efficient LED bulbs now. At 50,000 hour ratings, the energy saved over time more than covers the cost of the bulb. When I am done, I’ll be able to turn every light in my house on and still be at 150 watts of energy use.

  9. Melody

    Thank you Tony!!! Punctuation, Grammar & Spelling.
    (In order of importance) The keys to successful communication in (virtual)print.
    I was beginning to think the world was full of stupid idiots. I have been bothered by this ‘issue’ on 98% of websites everywhere. It IS annoying!!! I can only say to myself “typo” “english is not their 1st or even 2nd language” “public school” etc.,for just so long… as an excuse. I wonder if the authors understand the bigger message they send out-at least to me. I look at their words & most of the time beside irritation, I just get confused, there are unintended multiple meanings, no clarity. So I figure they couldn’t possibly know what they are writing about, doubt their facts, etc. and I am off to another page elsewhere. I realize I am possibly missing out on some great things but if I can’t check facts, why would I ever believe the info in front of me? From someone I don’t know, on anything important or mundane. People forget a very important ‘TRUTH’
    “Just by virtue of something being ‘found on line’ neither makes it REAL or TRUE.” Yes you still need to think for yourself folks. I think brains not faith, should be exercised here.
    So Thanks Tony, I guess I really need to get that off my chest! eheheheh I do feel better.


    YES, YES, YES!!! WE DO appreciate your efforts to publish your work!!! Your effort to help inform, educate and assist us, really.
    I just found your web site and I am so excited by it – I don’t have enough time in the day, to look at it all. I started with wifi ‘connection and range’ issues and I am an avid albeit new fan of Linux and the ‘Open Source’ movement – Ubuntu is the spirit! It seems every new link I click on brings me to another article I can’t wait to read! Thanks again to all of you, for ALL your work –

    Spread the ‘How to Geek’ word.

  10. sooopy

    Re: Tony.

    Stick to checking “you’re” stove and door locks 10 times before you go to bed. Microscopic OCD hairsplitting of “your” and “you’re” requires a psych & meds. Grrrr, “your” annoying me.

    (Go check the door again, you may have left it open last time.) :D

  11. Brett

    Thanks Melody. Wrong place really, but I too picked up on the error and agree fully. Am SO over it.

  12. Philipch

    “Grrr” does only need 3 r’s sooopy. Any more is wasteful – worth remembering in discussion of energy saving lights.

  13. AlanB

    Is that table correct? The mapping for 125W, the 22 just stands out as wrong.
    Actually, if you graph it, then 32 looks a better choice and would fit as a typo (i.e. “32 to 40”).
    Or does this mean that someone manufactures a VERY efficient 22W CFL?

    If you do graph it, the upper bound for 60W also stands out as inconsistent, but much less so. Maybe just a by-product of what CFL wattages are actually manufactured?

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