# 6308 bearing dimensions

A 6308 bearing is 40 mm bore × 90 mm outside diameter × 23 mm wide (1.575 × 3.543 × 0.906 in). The sealed version is 6308-2RS; the shielded version is 6308-ZZ.

## 6308 data

- Type: deep groove ball bearing, 63 series (medium)
- Bore d: 40 mm (1.5748 in)
- Outside diameter D: 90 mm (3.5433 in)
- Width B: 23 mm (0.9055 in)
- Bore code: 08 × 5 = 40 mm (from 04 up, multiply by 5)
- Sealed: 6308-2RS; shielded: 6308-ZZ; open: 6308

## Designations by maker

| Maker | Sealed | Shielded |
|---|---|---|
| SKF | 6308-2RSH | 6308-2Z |
| FAG (Schaeffler) | 6308-2RSR | 6308-2ZR |
| NSK | 6308DDU | 6308ZZ |
| NTN | 6308LLU | 6308ZZ |
| Koyo (JTEKT) | 6308-2RS | 6308ZZ |
| Timken | 6308-2RS | see catalogue |

## Same 40 mm bore, other series

| Bearing | Series | OD mm | Width mm |
|---|---|---|---|
| 6808 | thin-section | 52 | 7 |
| 6908 | thin-section | 62 | 12 |
| 6008 | extra-light | 68 | 15 |
| 6208 | light | 80 | 18 |
| 6308 | medium | 90 | 23 |


Load ratings and speed limits vary by maker: take them from the manufacturer's catalogue.

## FAQ

**What size is a 6308 bearing?**
40 mm bore, 90 mm outside diameter and 23 mm wide, which is 1.575 × 3.543 × 0.906 in.

**What does 2RS mean on a 6308 bearing?**
6308-2RS has rubber contact seals on both sides. 6308-ZZ (also written 6308-2Z) has metal shields on both sides. Both have the same 40 × 90 × 23 mm dimensions.

**Is 6308-2RS the same as 6308-ZZ?**
They are the same size and interchangeable in a housing. The sealed 6308-2RS keeps out fine dirt and water better; the shielded 6308-ZZ runs with less friction.

**What is the SKF equivalent of 6308-2RS?**
SKF writes it 6308-2RSH; FAG 6308-2RSR, NSK 6308DDU, NTN 6308LLU and Koyo 6308-2RS. Check the maker's catalogue for the exact seal type.

**What does the number 6308 mean?**
6 is the deep groove ball bearing type, 3 is the medium dimension series, and 08 × 5 = 40 mm (from 04 up, multiply by 5).

**Which bearings have the same bore as 6308?**
6808, 6908, 6008, 6208 also have a 40 mm bore, with different outside diameters and widths.

Source page: https://machinistcharts.com/bearing/6308/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)