E26 vs E27
E26 (US) and E27 (EU) are nearly identical in thread dimensions — 1mm separates them — and most bulbs physically fit both sockets. Voltage is the critical variable, not the base.
Side-by-side specs
| Spec | E26 | E27 |
|---|---|---|
| Base diameter | 26 mm | 27 mm |
| Thread pitch | Edison screw | Edison screw |
| Primary region | North America (120V) | Europe, Asia (220–240V) |
| Physical fit in other socket | Usually fits E27 | Usually fits E26 |
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Can you substitute one for the other?
Physically: usually yes. Electrically: only if voltage matches. An E26 bulb rated 120V will not produce full output or may fail in a 240V E27 socket. Always match bulb voltage to mains voltage.
Physical comparison (to scale)
Which devices take which
US fixtures use E26. European fixtures use E27. Globally distributed LED brands often specify both on the packaging.