Threaded screw base guide

E26

Medium screw

E26 is the standard medium screw base used by most household bulbs in the United States. Base and bulb shape are separate specifications.

Reviewed August 12, 2026
26 mm diameterNominal measurement · drawing not to scale
Connection
Threaded screw
Electrical context
The standard 120 V U.S. household base
Also called
Medium base, Standard base, Medium Edison screw, MES

How to identify E26

  1. Look for E26 on the bulb, fixture label, or package.
  2. The screw base is about one inch across.
  3. A common A19 household bulb usually has an E26 base.

Where it is commonly used

Table lampsFloor lampsCeiling fixturesRecessed cans

Common use is a clue, not proof. The fixture label and model documentation take priority over a visual match.

Bulb shapes sold with this base

You may see these shapes with a E26 base. The base code does not guarantee the bulb width, length, beam angle, or clearance.

A19A21BR30BR40PAR30PAR38G25ST19

Before you buy a replacement

  • E26 and E27 are close in size but belong to different voltage systems.
  • Confirm enclosed-fixture and dimmer ratings before switching to LED.
  • Match bulb shape and clearance as well as the base.