GU10 bulb base reference
GU10 is a twist-lock bi-pin spotlight base that runs directly on mains voltage (120V or 240V) with no transformer needed.
Exact specs
| Designation | GU10 (twist-lock) |
|---|---|
| Pin diameter | 10 mm (center-to-center) |
| Pin tip diameter | 6.35 mm (mushroom-shaped) |
| Voltage | Mains (120V US / 240V EU) — no transformer |
| Typical wattage | 5W–50W LED/halogen equivalent |
What fixtures commonly use it
Recessed downlights, track lighting, and kitchen under-cabinet spotlights frequently use GU10 in both the US and Europe.
What it's interchangeable with
GU10 LED bulbs can directly replace GU10 halogen bulbs of the same form factor. No driver or transformer change is needed.
What it's NOT interchangeable with
GU10 and MR16 are different systems. MR16 uses 12V low voltage (via transformer), while GU10 uses mains voltage. Their pin shapes also differ — pins lock in GU10, push in MR16.
Common mistakes
- Buying MR16 bulbs for GU10 fixtures — they will not fit or function.
- Assuming a higher-wattage LED will be brighter — check lumens, not watts.