Hey there! If you’ve ever bought light bulbs, you’ve probably seen that weird “B22” label on the packaging and thought, “Wait, what even does that mean? Is that how big it is?” As someone who’s been a B22 bulb supplier for over 7 years, I get so many questions about this—most of them being exactly that last one: what’s the actual size of a B22 bulb? Let’s break it down straight, no confusing engineering jargon, just the real stuff you need to know, plus a few pro tips from someone who deals with these bulbs every single day. B22 Bulb
First off, let’s get one tiny thing out of the way: a lot of folks mix up the socket size with the bulb size, but when we say “B22,” we’re talking about the socket first and the bulb’s base as part of that. Wait, hold on—let’s clarify. The “B” here stands for “bayonet” (you know, the push-twist base you click into place, way more common in the UK, Australia, New Zealand, and parts of Asia than the screw-type E27 you see a lot in the US). The “22” is the magic number everyone’s curious about, and no, it’s not the bulb’s height or how many watts it is. Nope, it’s the diameter of the bayonet base in millimeters. That’s it. So the metal part that slots into your light fixture’s socket is 22mm across. Got that? Let’s make it relatable—22mm is roughly 0.87 inches, so just under 9/10 of an inch if you’re used to imperial measurements. That’s the core size of the B22 base, which is what most people actually mean when they ask about the bulb’s size.
But wait, here’s where I see people mess up all the time: the base size isn’t the whole bulb. You can have B22 bulbs that are tiny little nightlights sticking out less than 2 inches, or big bright 100W equivalent LED bulbs that stretch 5 inches long, and both still fit the same B22 socket. So when someone asks “what’s the size of a B22 bulb,” I always follow up with “are you asking about the base, or the overall bulb length?” Because both matter for fitting in your light fixture. Let’s cover both, since that’s what actually matters for you as a buyer.
Starting with the base again, because that’s the non-negotiable part. B22 bases aren’t just a 22mm circle—they have those two little vertical pins on opposite sides, right? That’s what you align with the notches in the socket, push the bulb in, twist 90 degrees, and it locks. Those pins are spaced exactly 180 degrees apart, and the base’s total width (including the pins, wait no—wait, no, let’s get this right. The 22mm is the diameter of the circular part of the base without the pins. The pins themselves add a tiny bit, like a few millimeters each, so total width with pins is around 28mm. But the socket is cut to fit that 22mm circle and the pin spacing, so as long as the base is B22, it’ll clip in. I’ve had a guy come to me once saying his new bulb wouldn’t fit, and he’d bought a B22, turns out he’d measured the pins instead of the base—classic mistake.
Now, the overall bulb dimensions. This is the part that varies the most, because of what the bulb is designed for. Let’s go through common types, since that’s what most people care about. The standard old incandescent B22 bulbs—you know, the warm yellow ones that burn out in a year—were usually called “A60” or “GLS” (general lighting service). Those A60 bulbs have a maximum diameter of 60mm (that’s about 2.36 inches) and a total length from the bottom of the base to the top of the glass of around 105mm, or 4.13 inches. That’s the classic size that fits almost all standard B22 ceiling lights, table lamps, wall sconces—you name it. But LED versions of these GLS bulbs? They’re way shorter, right? Manufacturers make them with smaller heatsinks so they fit in tight spaces. I’ve got a standard 10W LED B22 GLS that’s only 80mm long, same base, fits in every fixture that takes the old incandescents.
Then there are other types: B22 golf ball bulbs (those round little ones for bathroom vanity lights or accent lamps). Those are like G30 or G45 bulbs, so their diameter is 30mm or 45mm, total length around 70mm for G45, way smaller than the standard GLS. Then you’ve got reflector bulbs, like PAR20 or PAR30, for spotlights or floodlights. Wait, do those come in B22? Yeah, a lot of outdoor security lights or track light fixtures use B22 bases for PAR20s, which have a diameter of 50mm and a length around 80mm. I’ve also worked with B22 candle bulbs for chandeliers—those are tiny, like E12 size but in B22, with a pointed top, total length around 100mm, base still 22mm.
Here’s a common headache for customers: if you’re replacing a bulb, never just buy “B22” without checking if the overall length fits your fixture. I had a customer last month who bought a set of bright B22 floodlights for his backyard, and they stuck out so far they hit his patio umbrella. Turns out he didn’t check the length—those PAR30 B22s were 120mm long, way longer than the 80mm PAR20 he’d had before. So always, always check two things: base size is B22, and overall length of the bulb is less than the space in your fixture between where the base sits and the top of the socket housing, or the clearance above the bulb. That’s the biggest mistake I see new buyers make.
Wait, let’s get back to the official specs for anyone who wants the hard numbers, no guesswork. The International Electrotechnical Commission (IEC) is the group that sets the global standards for these bulb bases, right? They define the B22 base as having a nominal diameter of 22mm, a pin center distance of 12.7mm, and the base’s total height (the part that slots into the socket) is around 10mm. That’s the official spec, so any legitimate B22 bulb will fit a B22 socket that meets IEC standards. The confusion only comes when unbranded, cheap bulbs skip the exact measurements, but as a supplier, I make sure every single B22 bulb we send out hits those IEC specs, so you don’t have that fit issue.
I should also mention: there are variations, but they’re not common. You might see something called “B22d” which is a double-contact bayonet, but that’s for industrial bulbs or specialized applications, not the household B22 most people buy. Stick to standard B22 unless you know you need the extra contact.
Now, why does this matter for you, the buyer or someone looking for bulbs? If you’re replacing a bulb, knowing the base is B22 means it’ll fit your existing fixture, but checking diameter and length means it won’t be too big or stick out weird. If you’re buying for a new build or renovating, making sure all your sockets are B22 (instead of E27, which is super common in the US) saves you from a hassle later. I’ve had contractors come to me because they mixed up E27 and B22 sockets on a house job—cost them time and money to replace all the sockets, so trust me on that part.
As a B22 bulb supplier, I’ve tested hundreds of bulbs over the years, and the only consistent number is that 22mm base diameter. Everything else is up to the bulb’s purpose, so don’t panic if one B22 bulb is twice as long as another. The best way to measure if a bulb will fit is to either take your old bulb to the store (or pull up a pic) or measure the interior of your fixture: the distance between the base opening and the highest point the bulb can reach, plus the space around the sides. If a bulb’s diameter is less than that side space and its length is less than the fixture’s internal depth, it’ll work.
Wait, let’s do a quick side-by-side to make it super clear:
- Standard GLS B22 (old incandescent): 22mm base, 60mm diameter, 105mm total length
- LED GLS B22: 22mm base, 60mm diameter, 80mm total length
- Golf ball B22: 22mm base, 45mm diameter, 70mm total length
- PAR20 B22 spotlight: 22mm base, 50mm diameter, 80mm total length
- Candle B22: 22mm base, 35mm diameter, 100mm total length
That’s all the common ones, right? I don’t want you to be stuck guessing.
Another thing I get asked a lot: why is it called B22 and not something else? The naming convention is pretty straightforward, actually. For bayonet bases, the first letter is B, and the number is the base diameter in millimeters, same as Edison screw bases are E plus diameter in mm. So E27 is Edison screw, 27mm diameter; B22 is bayonet, 22mm. That makes sense once you know it, and it’s saved me so many times when I’m on the phone with a customer who’s panicking about fitting.
As your go-to B22 bulb supplier, I’d be lying if I said there’s no confusion, but if you stick to two simple checks—base is B22, and overall dimensions match your fixture—you’ll never have a problem. If you’re not sure, just shoot me a message (no need for a fancy form, just tell me what you’re replacing or the fixture it’s going into) and I can point you to the right size. We’ve got everything from tiny 3W nightlight B22s to bright 15W outdoor flood B22s, all with that exact 22mm base so they fit every standard socket.
Wait, one last pro tip: if you’re buying multiple bulbs for the same space, make sure their total lengths are close, so they all look uniform. I had a customer once who bought two different brands of B22 LED GLS bulbs, one was 80mm long and the other was 95mm, so in his dining room, one bulb stuck out a full half inch more than the others—looked messy. Most reputable suppliers, like us, list the dimensions right on the product page, so you can check before you buy.
At the end of the day, B22 bulb size boils down to that 22mm base diameter, but don’t sleep on the overall bulb specs. Whether you’re replacing a burnt-out bedroom bulb, outfitting your whole house with LEDs, or picking bulbs for a new commercial space, knowing what you need (and asking if you’re not sure) will save you time, money, and frustration. If you’re looking to stock up on B22 bulbs for home, work, or resale, feel free to reach out to chat about your needs—we’ve got options for every use case, all tested for fit and quality. Don’t guess when it comes to bulb size; a quick check or a quick convo with someone who knows can make all the difference.
Festoon Bulb References:
- International Electrotechnical Commission (IEC). Standard IEC 60061: Lamp caps and holders together with gauges for the control of interchangeability and safety, 2020.
- Lighting Association. Guide to Bayonet Cap Bulbs, 2022.
- Energy Star. LED Bulb Specification Guide for Bayonet Bases, 2021.
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