# Edison screw lamp bases: E12, E14, E26, E27, E39, E40 thread sizes

> What are the thread diameter and pitch of E26, E27, E14 and E12 light bulb bases?

- Category: Home & kitchen › Household
- Kind: Standard part
- Basis: Wikipedia Edison screw table (IEC 60061-1 / ANSI C81.67 values); numbers only
- Page: https://xemstudio.com/objects/lamp-base-edison-screw/ · JSON: https://xemstudio.com/api/geometry?object=lamp-base-edison-screw · Plain text: https://xemstudio.com/objects/lamp-base-edison-screw/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- The number after E is the thread outer diameter in mm. E26 is the US medium base, E27 the European one; E12 is the US candelabra, E14 the European small base, E39 the US mogul.
- Pitch: E14 2.82 mm (9 threads per inch), E26 7 threads per inch (3.63 mm, computed 25.4 / 7), E27 3.62 mm, E40 6.35 mm. E12 and E39 pitch was not confirmed on a reachable page, so none is given.
- No file: the thread profile (flank angle, root and crest radius), base length and gauge shape are not published on any page available to Xem, and a plain cylinder at the major diameter would not be the base.

## Sizes

| base | thread outer diameter, mm | pitch |
|---|---|---|
| E12 candelabra | 12 | not confirmed |
| E14 small | 14 | 2.82 mm (9 per in) |
| E26 medium (US) | 26 | 7 per in = 3.63 mm |
| E27 medium | 27 | 3.62 mm |
| E39 mogul (US) | 39 | not confirmed |
| E40 goliath | 40 | 6.35 mm |

## Where the files are

- Wikipedia: [Edison screw](https://en.wikipedia.org/wiki/Edison_screw) — web — CC BY-SA; facts only

## Questions

**What is the diameter of an E26 base?**

26 mm thread outer diameter, 7 threads per inch.

**Is E26 the same as E27?**

No: 26 mm and 27 mm; they often screw in but are different standards.

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