E27 bulb base reference
E27 is the standard medium Edison screw base used in Europe, the UK, and most of Asia, measuring 27mm in base diameter.
Exact specs
| Designation | E27 (Medium / Standard International) |
|---|---|
| Base diameter | 27 mm |
| Thread pitch | Edison screw (E-series) |
| Primary region | Europe, UK, Asia, Australia (220–240V systems) |
| Typical wattage range | 10W–150W (incandescent equivalent) |
What fixtures commonly use it
Standard European and UK lamps, overhead fixture sockets, and pendant lights use E27 as the household default.
What it's interchangeable with
E27 and E26 threads are nearly identical. An E26 bulb will usually fit an E27 socket and vice versa. Functional compatibility depends on voltage — do not use a 120V-rated bulb in a 240V socket.
What it's NOT interchangeable with
E27 is not compatible with E14 (smaller European screw), E12 (US candelabra), bayonet B22, or any pin-type base.
Common mistakes
- Assuming E27 and E26 are identical — the 1mm difference is rarely a fit problem, but voltage matters.
- Using 120V bulbs in 220V countries without checking wattage.