Last updated: 26 August 2026

B22 vs B22d

For almost everyone, B22 and B22d are the same thing. "B22" is the everyday name for the 22mm bayonet fitting — the push-and-twist bulb (or globe) common across Australia, the UK and beyond. "B22d" is simply its full technical name. If a shop lists a bulb as B22d, it will fit your ordinary B22 bayonet socket.

What the "d" means

The letters and numbers are a standard code. B is bayonet, 22 is the diameter in millimetres, and the d stands for double contact — there are two little electrical contact points on the bottom of the base. Practically every household bayonet bulb is double-contact, so "B22" and "B22d" refer to the same everyday fitting. Manufacturers just use the longer form on spec sheets.

Is there a B22s?

Yes, but you'll rarely meet it. B22s is the single-contact version — one contact point instead of two. It turns up in some specialised, automotive and older festoon-style fittings, not in standard home lighting. Unless your fitting specifically calls for single-contact, you want the ordinary double-contact B22d.

Which one do I need?

For normal household lamps and ceiling fittings, buy a B22 / B22d bayonet bulb — they're one and the same, so either label is correct. The only thing to actually check is bayonet versus screw: if your old bulb pushes in and twists to lock it's bayonet (B22); if it screws in, it's an Edison screw (E27). That's the distinction that trips people up, not the "d".