Strictly speaking MR16 is not a socket but a reflector size: a mirrored reflector 50 mm across. The socket underneath it is called GU5.3 and runs on 12 volts. In practice everyone uses MR16 as the name for that whole 12V spot.
Where the designation comes from
MR stands for Multifaceted Reflector: a reflector with facets that shape the beam. The number is the diameter in eighths of an inch. Sixteen eighths is two inches, or 50 mm.
That is how you read the other sizes in the same family too:
- MR11 — eleven eighths of an inch, about 35 mm
- MR16 — sixteen eighths of an inch, 50 mm
So the number says nothing about the socket, the power or the voltage. Only about how big the head is.
MR16 almost always comes with GU5.3
The reflector is attached to a socket, and with MR16 that is in practice always GU5.3: two thin straight pins 5.3 mm apart, which you push straight into the holder. That means 12 volts, and therefore a transformer or driver above the ceiling.
This is why you see "GU5.3 / MR16" used interchangeably in product descriptions. Strictly the first is the socket and the second the reflector, but they refer to the same lamp.
MR11 in our range
Two fixtures in the catalog are built around the smaller MR11 size:
- Rondo recessed spotlight — MR11, cut-out size Ø48 mm, tiltable, €8.95
- Trimo trimless fixture — GU10 or MR11, cut-out size Ø50 mm, IP20, €11.95
That small size is exactly why MR11 exists: where a 68 mm hole is too large, a 35 mm reflector still fits. For accent light in a niche, a cabinet or a narrow beam, that is the difference between possible and not.
Where you meet MR16 in our range
Four recessed spotlights take either GU10 or MR16, and they say so:
With those four you choose. Take GU10 and you connect straight to 230 volts. Take MR16 and you need 12 volts and therefore a driver — our 20-watt 12V driver feeds a maximum of six spots, the 40-watt version ten.
Our advice: only choose it if it is already there
If you are installing from scratch, take GU10. No transformer, no minimum load, no voltage drop along long thin cables. Only choose MR16 if there is already a working 12V installation you do not want to change.
And in that case, do replace the halogen transformer with an LED driver. An old transformer needs 20 watts or more to engage, and a few LED spots never get there — then it flickers.
Why the reflector matters less with LED
With halogen, the reflector was the part that made the beam: a filament radiated in every direction and the mirror aimed that light forwards. So the MR designation genuinely told you something about how the light behaved.
An LED already radiates in only one direction. The reflector still matters for the beam angle, but far less than it used to, and on some LED lamps the mirrored shape is only a shell that fits the old holder. So do not compare on the MR size but on the stated beam angle if you want to know how wide the beam will be.
Watch the head, not just the socket
If you buy a loose MR16 lamp, check the length and the beam angle too. The reflector diameter is fixed at 50 mm, but the depth is not: a longer lamp does not always fit a shallow fixture. That goes especially for recessed spotlights with little room above them.
More about the distinction between the two sockets in What is the difference between GU10 and GU5.3? The full range is with the recessed spotlights.
Is MR16 the same as GU5.3?
Not exactly. MR16 is the 50 mm reflector, GU5.3 the socket underneath. In practice the names are used interchangeably for the same 12V spot.
What does the 16 in MR16 stand for?
Sixteen eighths of an inch, or 50 mm across. On an MR11 that is eleven eighths, about 35 mm.
Does an MR16 lamp work on 230 volts?
No. MR16 with a GU5.3 socket is 12 volts and needs a transformer or LED driver.