Can I swap an MR16 bulb for a GU10?

Not directly. GU10 is mains voltage and MR16 is low voltage with a different holder, so they are not interchangeable. Converting from one to the other means changing the fitting and wiring, which is a job for a qualified electrician.

Why does my MR16 LED flicker but the GU10 does not?

MR16 spotlights run through a transformer that may not be rated for LEDs, which is a common cause of flicker. GU10s run straight off mains power, so they avoid that particular problem.

Last updated: 19 August 2026

GU10 vs MR16 spotlights

GU10 and MR16 are the two common spotlight fittings — the little two-pin bulbs (or downlight globes) in downlights and track lights. They look almost identical, but they run on completely different voltages, which is why you can't simply swap one for the other.

The key difference: voltage

GU10 runs on mains voltage (230V). It has two chunky pins with rounded tips, and you push it in and twist a quarter-turn to lock — the "twist-lock" spotlight. Because it runs straight off mains power, there's no transformer involved.

MR16 runs on low voltage (usually 12V) through a transformer or driver. It has two thin straight pins that push into the holder. That transformer is the source of a lot of MR16 headaches — if it isn't rated for LEDs, the bulb can flicker.

A quick technical note: strictly speaking, “MR16” describes the reflector shape and size, not the base — the familiar low-voltage two-pin base is actually called GU5.3. Almost everyone says “MR16” to mean the low-voltage spotlight, so that's how we use it, but if you see “GU5.3” on a bulb or fitting, it's the same thing.

How to tell them apart

	GU10	MR16
Voltage	Mains (230V)	Low (12V)
Pins	Two chunky, rounded tips	Two thin, straight
Fitting	Push & twist-lock	Push-fit
Transformer	None	Yes

Which one do I have?

Take the globe out and look at the pins. Two chunky pins with little rounded knobs on the tips, set fairly far apart, that you twist to lock — that's a GU10. Two thin, straight pins close together that pull straight out — that's an MR16 (GU5.3). If you can see a chunky separate transformer box in the ceiling cavity above the light, that also points to MR16. Still unsure? Our bulb base finder walks you through it.

Replacing old halogen downlights

Most older Australian downlights were low-voltage MR16 halogens. Since halogen was phased out in 2020, people are swapping them for LED — and here's the catch: an LED MR16 globe will only work if the existing transformer is happy driving an LED load. Many aren't, which is why the new globe flickers or won't light. Where the transformer needs replacing, or you're moving to mains-voltage GU10 or an integrated LED downlight, that's wiring work for a qualified electrician. If you're simply swapping a working globe like-for-like, match what you already have.

Why you can't just swap between them

Because the voltage and holder are different, a GU10 won't work in an MR16 fitting or vice versa. Converting a set of downlights from one to the other means changing the fittings and wiring — electrical work for a qualified electrician, not a DIY globe swap. If you're only replacing the globe, match what you already have.