What Exactly is A GU24 Bulb?

This post has been updated from its original 2008 version.

You may have heard of the GU24 bulb and wondered what they are. Available in both CFL and LED, these bulbs have a different base than the standard screw base bulbs. GU24 bulbs have 2 pins protruding from the base instead of the usual screw in base. To install the bulb, you would insert the pins into the corresponding holes in the socket and twist the light bulb and lock it into place.

So why would you want to use a bulb with this base? What are the advantages?

  • The GU24 bulb is self-ballasted i.e., the ballast portion of the bulb is already attached to the bulb and is easy to replace.
  • The overall length of the bulb is shorter since the ballast and the bulb are in one unit
  • You can easily change the wattage of the bulb, unlike pin base bulbs which require the socket to be changed for different wattages of bulbs. This offers more flexibility.
  • The size and shape of socket is similar to an incandescent socket so it’s great for homes.
  • A standard GU24 Bulb is interchangeable between manufacturers.
  • The LED GU24 Bulb is long lasting with an expected life of 25,000 hours of life which decreases the need for regular replacement. At Conservation Mart we offer these bulbs in a variety of color temperatures ranging from 2700K to 4000K.

So next time you’re in the market for a lighting fixture, consider one that utilizes a GU24 base bulb.

Shop now for GU24 base bulbs>>>

Maxlite 9W LED Omnidirectional A-Lamp GU24 A19 4000K 9A19GUDLED40
Maxlite 9W LED Omnidirectional A-Lamp GU24 A19 4000K 9A19GUDLED40
Earthtronics 8.5W LED Omni A-Lamp GU24 A19 5000K  LA19850V224
Earthtronics 8.5W LED Omni A-Lamp GU24 A19 5000K LA19850V224



40 thoughts on “What Exactly is A GU24 Bulb?

  1. Anonymous says:

    How well do these bulbs work in an exterior setting where it’s below freezing (or even below zero)?

  2. Dave says:

    Does it make sense to throw away the ballast every time you change a lamp?

    The ballast adds to the overall length of the lamp, limiting the fixtures it can be used in and limiting the design flexibility of the fixture designers.

    What is the mean lumens rating for the lamp?

  3. Anonymous says:

    The bulbs work as well as any other CFL in outdoor settings, with the GU24 connection having no bearing on its outdoor performance (it’s just another way to make an electrical connection). The manufacturer might make the bulb for exterior settings with features like pre-start heating or a shorter arc length, but you’ll need to find the bulb specification to determine if the lamp will start in the setting you’re planning on. Generally speaking, freezing is pushing it for most fluorescent bulbs, but there are bulbs that can get down to the -20 F range.

    And no, Dave, it doesn’t make a whole lot of sense to toss the ballast when the lamp is changed. However, ballasted CFLs probably make up the cost of the ballast in energy savings if they’re replacing an incandescent bulb. If you really want to be efficient, get dedicated fluorescent fixtures that use T5 HO bulbs… from the information I’ve compiled, these give off the most lumens/watt with the least waste material. Keep an eye on solid state lighting such as LEDs, though; their price continues to drop and the efficiency and quality keep climbing as research continues. The lifespan of LEDs is already exceedingly high where light fixtures are concerned, and there isn’t the mercury waste issue encountered with fluorescent bulbs.

  4. Jesse says:

    I just had two GU24 CFL bulbs replaced. Each bulb (13 watt)is $7.00. At that price I would rather have a regular screw-in CFL bulb. I considered replacing the bulb socket to a regular screw-in, but I thought I’ll just do it next time since the whole fixture is attached to the outside wall, on a stucco, and is caulked on the sides. In order to replace the socket, you have to have enough wire slack and since you can’t pull the wire to have a slack, you need to take whole fixture from the wall. I am also thinking about putting an adapter to the socket so I can use the regular screw-in type. I think the price of these GU24 CFL Bulbs don’t justify their advantages.

  5. Conservation Mart says:

    Sorry to hear you’ve had a negative experience in terms of the pricing of these bulbs. We have a large selection of GU24 CFLs, some priced as low as $3.40. Hopefully the cost you paid last time hasn’t completely ruined your perception of these lights.

  6. salyavin says:

    The bulbs do cost more, I suspect this is due to the bulbs being self ballasted. There is also not much in LED for this socket. As we are creating more waste by throwing away the ballast each time these are certainly anticoncervation. Seems to be a lose-lose for the end user. Pay more for the bulbs, less selection, more waste. If one wants to replace the edison screw for a good technical reason that would be just fine but here we have no gains and a lot of negatives. For now I suggest keeping the edison screw with the ballast so we don’t throw it away all the time and can use a much wider selection of bulbs at a lower cost.

  7. jason@6500k cfl says:

    i like G24 base rathan than E27 base.
    some of my bulb with e27 base got corrosion.
    I don’t know why this would happen.

  8. Marisano says:

    Sorry salyavin, the E27 (Edison-style screw in) CFLs are also self-ballasted. That’s why you can simply plug them into an old incandescent fixture and they just work. But there aren’t really any advantages to the GU24 connector style. It’s just there so consumers can’t (easily) go back to using incandescent bulbs, which are far more energy intensive.

  9. Kyle says:

    I agree with Jesse. I’ve had the same issue. I just bought a home that was fully redone prior to us buying it and the old owner put in these twist lock fixtures. I installed a dimmer for my basement and then realized that it would cost $60 just to replace the 6 bulbs with dimmable ones. Not happy. I’m considering getting the normal fixture to put back in there.

  10. Sylvester says:

    I had the same problem with Jesse and agreed with what he said. I installed that 4 of those lamps in 2010 because the CITY required them. Two bulbs had burned so far. It cost me $12 just to replace the first. Now I am looking at how I can change the whole fixture to the screw-in type. Can some one advise please.

  11. Glenn says:

    Hi Sylvester. Me too. It must be fairly easy to just rewire the base part so it will accept a regular screw in bulb. Does anyone know of any practical reason (other than energy efficiency) why this should not be attempted for a bathroom ceiling fan/light? Or is this not as easy as it might seem to a novice? I imagine the incandescent will burn hotter but the light from these CFLs is pathetic.

  12. Ted says:

    Glenn, The GU24 connector is not inherently more energy efficient. All that really matters is the energy efficiency of your lamp/bulb. There are GU24 to E26/E27, Edison screw, adapters available. As always with lighting, the key thing is to make sure the wattage of your lamp/bulb doesn’t exceed the wattage rating for your fixture. Or just install a fixture that supports the lamp you want to use.

    Perhaps unsurprisingly, all of the benefits listed here also apply to Edison screw style CFLs. As near as I can tell GU24 only exists to encourage Californians to throw out otherwise functional Edison screw hardware. I got a free GU24 desk fixture at some point. I will probably just replace the whole fixture if the bulb dies.

  13. Lisa says:

    I purchased this beautiful light fixture to hang over my kitchen table and now I can’t see my food! I purchased the fixture not knowing what GU24 meant, but never thought I would be so limited in the bulbs I can use. I need something that can shine bright while we eat, yet be dimable for use as ambient lighting.
    Is it easy enough to change the base so I can use a higher wattage bulb without it flickering constantly? I love the fixture, it took a long time to find one that worked with the decor, I’d rather fix the problem and keep it, if possible.
    Any suggestions?

  14. Conservation Mart says:

    Hi Lisa,
    GU24 bulbs come in a many different watts, and some dimmable options are available as well. The brightest one that we sell is a 23-watt, which is the equivalent of a 100-watt incandescent bulb. If you need a brightness level that is less than this, we offer an 18-watt GU24 bulb, which gives off a light equal to that of a 75-watt incandescent. Our full product offering of dimmable GU24 bulbs is listed here: http://www.conservationmart.com/c-24-gu24-base.aspx#Filter=[EntityIDs=@(39)@*ava=1]


  15. Steve says:

    I agree that all of the advantages listed for the GU-24 base are just as true for Edison base CFLs or LEDs. But you are dead wrong about California rebates for GU24 lamps. Never happened. In fact screw-in or pin-based LED lamps are specifically excluded from rebates in N CA. And approved lamps in S CA are almost exclusively Edison based.

  16. Kat says:

    I have a bathroom light fixture that looks like it has the gu24 pins but my pins are further apart like an inch apart what is the code for that

  17. Conservation Mart says:

    Hi Kat! Have you tried checking under/around the bulb for that code? As far as the twist-and-lock models go, GU24 is the widest twist-and-lock base we have.

  18. Conservation Mart says:

    Hi Kalos,
    It may be on the market, but that’s unfortunately not an item we currently carry.

  19. Dan says:

    Do the G-24 socket corrode easier when used outside. All four outside lights fail to light even with power to them

  20. Conservation Mart says:

    The GU24 bulbs aren’t interchangeable with the GU35. You’ll want to find a bulb with the same base configuration.

  21. Tim Chmiel says:

    I have 2 gu24 lights in a hallway. They are 13 w bulbs. the bulbs i have are 900 lumens and 5000 k. Is there a brighter bulb as the hall seems dark? Can I use a high watt or led to make brighter? I see there are replacement for higher than 60 watt CFL’s.

  22. Deborah Julik-Heine says:

    My light bulb (apparently) burnt out, so I replaced it with a 100 watt one (23W as printed on the fixture). It was difficult to twist it in properly so that it wouldn’t hang down a bit, but I managed to get it to click, but NO light when I flipped the switch. Am I doing something wrong here?

  23. Conservation Mart says:

    Hi Deborah. It could be an issue with the fixture. Have you tried contacting the manufacturer of the fixture to troubleshoot?

  24. Conservation Mart says:

    Hi Tim. The 13W are a great replacement for 60W, so great choice there. As far as lumens go, 950 is the highest that we’ve seen for a 13W GU24 CFL. If the fixture will allow for a higher wattage than 60W though, that will allow you to use a replacement bulb with a higher lumen rating as well, thus brightness. Make sure you double check the fixture before going higher though, as that can possibly cause a shortage in the fixture.

  25. Aaron says:

    I’m having trouble finding ‘smart’ bulbs with GU24 base although GU10 is readily available. Is there a reason for this?

  26. Dale says:

    I have the GU24 base bulbs in my bathroom vent fans. I bought the fans from Lowe’s. One of the bulbs finally burned out and all the replacement bulbs I have purchased are too big. The prongs go in place but won’t twist because they are just a fraction too big. FYI don’t squeeze the bulbs trying to lock them in cause they will break in your hand.

  27. J freeland says:

    I have a lamp that needs a g26 base, but I can’t find them can I use a gu24

  28. briana says:

    Do they even make color changing GU24 bulbs?? I am looking for one for the holidays and can’t find any! It seems like I could buy a color changing edison bulb and then get a GU24 adapter to screw it into. But that sounds hazardous, is it safe?

  29. Ron Rice says:

    My apartment has Satco bulbs with a GU24 base. I attempted to replace them with Simba bulbs that also have a GU24 base. They did not fit because the distance between the pins is shorter for the Simba bulbs by about two millimeters. That pin width is not even listed as part of the specs for any of the bulbs I have seen. How can I know whether a particular G24 base will fit my existing GU24 socket? TIA

  30. Dorothy Chun says:

    I have a similar question, I think. The Feit GU 24 bulbs that I just purchased fit very loosely into my hanging light fixture. Unless the bulb is positioned perfectly, it doesn’t work. How can I make the fit tighter?

  31. Ida Mason says:

    I need a GU30 but can only find GU24. Can I use a GU24? If not, where can I find a GU30?

  32. Susie says:

    Are GU24 sockets replaceable? Our light bulbs will no longer screw in and stay in the fixture. They would fall out if I let go.

  33. Josh laplante says:

    Is there a GU18 bulb. My bulbs just went out and I have a mls18GU 18W 130V 84CRI. I dont know what to buy for a bulb.

  34. Harry says:

    I just moved into a house and several bulbs need to be replaced. They have this goofy base apparently called a “GU24”. Took me a long time to find that base name. Can’t find the bulbs at WalMart or Home Depot. Why would anyone use these non-standard, expensive, hard-to-find bulbs? What is wrong with the standard Edison base?

  35. Pilar Gonzalez says:

    Just replaced a Seagull#97102 Type T-3 lamp with a GE relax LED A19 GU24. It goes one when I turn the switch on, but then it goes off a few seconds later. Tried several times; only stays on for a few seconds. What can be the Problem?

  36. Conservation Mart says:

    Hi Brandon. The pins have difference in distance. 24mm for the GU24, and 26mm for the GU26. Because of this difference, the two lamps aren’t interchangeable.

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