# Scope dovetail rails: 11 mm (European) and 3/8 in (US), and Weaver

> What are 11 mm and 3/8 in dovetail and Weaver rail dimensions?

- Category: Hardware › Mounting standards
- Kind: Standard part
- Basis: Published dimensions only (Optics Trade technical article; Brownells GunTech via AccurateShooter); groove depth and height are not standardized, so no file
- Page: https://xemstudio.com/objects/scope-dovetail-rails/ · JSON: https://xemstudio.com/api/geometry?object=scope-dovetail-rails · Plain text: https://xemstudio.com/objects/scope-dovetail-rails/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

- Airguns, rimfire rifles and many airsoft and crossbow scopes use a plain dovetail instead of Picatinny.
- 11 mm dovetail: 11 mm across the top with 60° sides (the European standard). 3/8 in dovetail: 12.7 mm across the top with 45° sides (the US standard); the 3/8 in is measured across the bottom. Their depths and heights vary by maker, so Xem publishes no file: measure your rail's height before designing a clamp.
- Weaver: grooves .180 in wide, with no standard centre-to-centre spacing.
- Picatinny (MIL-STD-1913) is fully specified: see its page for the complete profile and files.

## Sizes

| rail | top width | side angle | groove |
|---|---|---|---|
| 11 mm dovetail | 11 mm | 60° | none |
| 3/8 in dovetail | 12.7 mm (3/8 in across the bottom) | 45° | none |
| Weaver | not standardized | — | .180 in wide, spacing not standardized |

## Where the files are

- Optics Trade: [11 mm and 3/8" dovetails](https://www.optics-trade.eu/blog/11-mm-and-3-8-dovetails/) — web — Publisher's page; dimensions are facts
- AccurateShooter (Brownells GunTech): [Picatinny vs. Weaver rail specifications](https://bulletin.accurateshooter.com/?p=5211) — web — Publisher's page; dimensions are facts

## Questions

**Are 11 mm and 3/8 in dovetails interchangeable?**

Not with ordinary mounts: 11 mm is 11 mm wide at 60°, 3/8 in is 12.7 mm at 45°; some mounts with reversible clamps fit both.

## Fits with

- [Picatinny rail (MIL-STD-1913): profile, grooves and mount jaw](https://xemstudio.com/objects/picatinny-rail-mil-std-1913/)
- [Dovetail rail and slide mount (60°)](https://xemstudio.com/objects/dovetail-rail-mount/)