# Push-to-connect pneumatic fittings: tube OD 4 to 12 mm and 1/8 to 1/2 in with the thread sizes offered

> Which tube sizes and thread sizes do push-to-connect fittings come in?

- Category: Tri-clamp & pipe › Pipe, tube & threads
- Kind: Standard part
- Basis: SMC KQ2H male connector series listings (metric and NPT inch ranges); numbers only
- Page: https://xemstudio.com/objects/push-to-connect-fitting-sizes/ · JSON: https://xemstudio.com/api/geometry?object=push-to-connect-fitting-sizes · Plain text: https://xemstudio.com/objects/push-to-connect-fitting-sizes/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

- Push-to-connect (push-in, one-touch) fittings take tube by outside diameter: metric 4, 6, 8, 10, 12 (and 16) mm, inch 1/8, 5/32, 1/4, 5/16, 3/8, 1/2 in. The table lists the male threads SMC offers on its straight male connector KQ2H for each tube OD (metric: tapered R, ISO 7, or M5/M6; inch: NPT). A tube must match the OD to within the maker's tube tolerance; soft PU/nylon tubes in the same nominal OD are not interchangeable with hard ones.
- Tube dimensions (OD, ID, wall) of PU tube are on the PU pneumatic tube page. 5/32 in is 3.97 mm, 1/4 in is 6.35 mm, 3/8 in is 9.53 mm: metric and inch tubes of similar size do not interchange (6 mm vs 1/4 in leaks or blows out).
- Left out, no file: collet and cartridge bore, hex size and body length are in SMC's PDF catalogue (not readable here) and Festo/Legris tables were not checked; retail pages do not print them, so we publish no body.

## Sizes

| tube OD | male threads offered (SMC KQ2H) |
|---|---|
| 4 mm | R1/8, R1/4, M5, M6 |
| 6 mm | R1/8, R1/4, R3/8, M5, M6 |
| 8 mm | R1/8, R1/4, R3/8 |
| 10 mm | R1/8, R1/4, R3/8, R1/2 |
| 12 mm | R1/4, R3/8, R1/2 |
| 16 mm | R3/8, R1/2 |
| 1/8 in | NPT 1/16, 1/8, 1/4 |
| 5/32 in | NPT 1/16, 1/8, 1/4 |
| 1/4 in | NPT 1/16, 1/8, 1/4, 3/8 |
| 5/16 in | NPT 1/8, 1/4, 3/8 |
| 3/8 in | NPT 1/8, 1/4, 3/8, 1/2 |
| 1/2 in | NPT 1/4, 3/8, 1/2 |

## Where the files are

- SMC Pneumatics (distributor): [KQ2H male connector, metric](https://www.smcpneumatics.com/mkq2h.html) — web — Publisher's page; dimensions are facts
- SMC Pneumatics (distributor): [KQ2H male connector, inch tube, NPT](https://www.smcpneumatics.com/newKQ2Hnpt.html) — web — Publisher's page; dimensions are facts

## Questions

**Does 1/4 in tube fit a 6 mm push-in fitting?**

No: 1/4 in is 6.35 mm. It does not seal reliably in a 6 mm fitting; use the matching inch fitting.

**What threads come on 6 mm push-in male connectors?**

SMC KQ2H 6 mm: R1/8, R1/4, R3/8, M5 and M6.

## Fits with

- [PU pneumatic tube 4 to 12 mm OD (push-fit sizes)](https://xemstudio.com/objects/pu-pneumatic-tube/)
- [Push-fit fitting envelopes: 4 / 6 / 8 mm tube, G1/8 and G1/4 thread stubs](https://xemstudio.com/objects/push-fit-fittings/)
- [NPT male thread envelopes 1/8 to 1 in (ASME B1.20.1)](https://xemstudio.com/objects/npt-thread-envelopes/)
- [BSP (G) male thread envelopes 1/8 to 1 in (ISO 228-1)](https://xemstudio.com/objects/bsp-thread-envelopes/)
- [Hose barbs for 2, 3, 4, 6 and 8 mm ID tube](https://xemstudio.com/objects/hose-barbs/)