Today’s LED light bulbs are brighter and more efficient and more durable than ever. They dim smoothly, have very good colour rendition and choice of colour temperature. Best of all, pricing is coming down as quality goes up. Now, LED light bulbs are being produced in virtually every shape and base size. In this article, we’ll explain the most popular alpha-numeric designations, so it will be easy for you to find just what you need to replace traditional light sources everywhere in your home and business. If you do not see your base type or bulb shape, here is a complete list of bases and bulb shapes. Lamp Base Types:
E-12 candelabra base: This type of base typically is found in chandeliers, wall sconces and some bath bars. It is typically topped by a blunt tip, flame tip, or globe shaped bulb. There are also E-11 mini candelabra bases and E-14 European bases. Although all are referred to as ‘candelabra’, they are not interchangeable.
The E17 intermediate base is in between a candelabra base and a medium base. These are frequently found in commercial Exit signs. The intermediate base is sometimes used in ceiling fans and appliances. Although a lamp base adapter may be used, it’s best to make sure an appliance is suited for a LED bulb replacement. LED bulbs are not advised for use with some appliances such as microwaves and range hoods, although they are just fine in refrigerators. 
E-26 or E-27 medium base. This is the most common base type used for light bulbs in the USA. It’s the standard household base which can be topped by many different shapes. When you think medium base, think of the standard lamp you would put in a table lamp or light fixture in most places around the home. Browse our LED light bulbs.
E-39 E-40 Mogul Base. Except for commercial lighting applications, this base size is somewhat of a dinosaur. Sometimes made of ceramic, the mogul base incandescent bulb was used in torchiere lamps and had to be larger and sturdier to take the heat a 300W incandescent bulb produced. You may want to think of a lamp base adapter to size this down so you can use a medium base LED bulb
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There are several other types of fluorescent bases; only the two most common are shown here. Typically, a fluorescent tube has two pins or one larger single pin in the centre. Check with your electrician as he or she may be able to replace the ‘tombstones’ in your fluorescent fixtures more economically than waiting for supply on one type or the other. A ‘tombstone’ is the receptacle the bulb sits into. Our LED Fluorescent Replacements shine!
The GU-10 base is typically found in bath bars, ceiling fans and track lighting. GU-10 halogens typically operate at 120VAC. Our LED GU-10 replacements also operate at line voltage, so there is no need to worry about transformers or trying to make an ant learn new tricks.This is a twist and lock type base.
The GU-5.3 is an MR-16 type lamp base. It has two pins. MR-16’s are found in track lighting heads, bath bars, some ceiling fans. Our LED replacement MR16 lamps operate at low voltage and work particularly well with magnetic transformers. If you have an electronic transformer, you will want to purchase just one LED MR16 to try in your fixture to make sure it will work properly. Lamp Shapes:
A-shape. Not so sure why this is called A. It doesn’t look like an A unless you turn it upside down. Perhaps it’s because it’s the first type of light bulb produced. It’s more of a pear shape. It won’t be long before the next generation has no clue what we mean when we say “like a 60-watt incandescent bulb”. Soon enough, people won’t know what that is. The most common A shaped bulbs are A19’s and A15’s. The A15 is smaller and is often found in refrigerators and bath bars and can easily be used in some chandeliers.
Our LED A-shape bulbs are available in a medium or candelabra base.
B stands for Blunt as opposed to ‘flame tip’ bulbs of this type. These can be had with candelabra or medium bases. You would typically choose a blunt shape in more contemporary chandeliers if the bulb itself were seen. Its counterpart is the flame tip bulb. It has a more traditional appearance and goes well with more traditional crystal and brass chandeliers, or in the type of candle lights, you would place on windowsills at Christmas time
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G is an easy one. G stands for Globe shape. The G 16 1/2 is much smaller in diameter than the G-25. It is available in candelabra or medium base. The G-25 is larger. It’s the size of the globe shape bulbs you may have in a bare light bar above your vanity. The G-25 is medium base only. You have your choice of colour temperatures in both variations. in stock here at TheLEDLight.com in both types.
R stands for the reflector. The numerical designation indicates how wide the bulb is. LED lamps are available in sizes from R20 up to R40
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You’ll find these in gimbal track rings, recessed cans, indoor and outdoor spot and flood fixtures. The R type bulb is usually not waterproof but can be used in a fixture protected from the weather as long as it is not sealed. LEDs need room to breathe. Cooping them up inside a closed container will short the life of your LED bulbs. Find our LED R lamps here. 
BR stands for ‘bulged reflector’. The ‘bulge’ allows the light to be distributed in a subtly different manner. It is very pleasing to the eye. You will see by comparison to the R-20 shown above, that the glass part is more curved. It’s optical, but not an optical illusion! Take a look at this 250W LED Replacement BR40.
MR stands for ‘mirrored reflector’. We still call it that in the LED industry, but a LED MR-16 doesn’t require those tiny mirrored squares to put the light where you want it to be. MR16’s are found in track lighting and all kinds of display case lighting. We now have a 50W equivalent (to a halogen) at a fraction of the wattage consumption and without all that heat. And next, the PAR lamps. PAR stands for Parabolic Reflector. The guts are U-shaped. Once again, the LED PAR bulbs don’t require that to produce the same kind of light output and performance as the traditional PAR. You’ll see either an “S” or an “L” in this bulb shape description. That stands for either short neck or long neck. What you want to consider is how deep is your fixture. Measurements are always on our site for each type, so you can easily decide which length you need .
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And last but not least, you have the T-shaped bulb. T stands for ‘tube’. T-type bulbs are found in things like bankers lamps and podium lights. The T designation also fits fluorescent tube replacements. The number associated with it determines the bulb diameter. So there you have it … common lamp base sizes and bulb shapes in a nutshell. If you don’t see what you’re looking for, we have a more extensive list available by PDF download. There are times when you’ll be much better served to use a lamp base adapter so you can conveniently use a brighter, better-LED bulb. And of course, if you need help, we’re always here to offer assistance. Thank you as always for checking in with us. Stay tuned for our next article early next week.
By: Mary Wecker
