# 6904 bearing dimensions

A 6904 bearing is 20 mm bore × 37 mm outside diameter × 9 mm wide (0.787 × 1.457 × 0.354 in). The sealed version is 6904-2RS; the shielded version is 6904-ZZ.

## 6904 data

- Type: deep groove ball bearing, 69 series (thin-section)
- Bore d: 20 mm (0.7874 in)
- Outside diameter D: 37 mm (1.4567 in)
- Width B: 9 mm (0.3543 in)
- Bore code: 04 × 5 = 20 mm (from 04 up, multiply by 5)
- Sealed: 6904-2RS; shielded: 6904-ZZ; open: 6904

## Designations by maker

| Maker | Sealed | Shielded |
|---|---|---|
| SKF | 6904-2RSH | 6904-2Z |
| FAG (Schaeffler) | 6904-2RSR | 6904-2ZR |
| NSK | 6904DDU | 6904ZZ |
| NTN | 6904LLU | 6904ZZ |
| Koyo (JTEKT) | 6904-2RS | 6904ZZ |
| Timken | 6904-2RS | see catalogue |

## Same 20 mm bore, other series

| Bearing | Series | OD mm | Width mm |
|---|---|---|---|
| 6804 | thin-section | 32 | 7 |
| 6904 | thin-section | 37 | 9 |
| 6004 | extra-light | 42 | 12 |
| 6204 | light | 47 | 14 |
| 6304 | medium | 52 | 15 |


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

## FAQ

**What size is a 6904 bearing?**
20 mm bore, 37 mm outside diameter and 9 mm wide, which is 0.787 × 1.457 × 0.354 in.

**What does 2RS mean on a 6904 bearing?**
6904-2RS has rubber contact seals on both sides. 6904-ZZ (also written 6904-2Z) has metal shields on both sides. Both have the same 20 × 37 × 9 mm dimensions.

**Is 6904-2RS the same as 6904-ZZ?**
They are the same size and interchangeable in a housing. The sealed 6904-2RS keeps out fine dirt and water better; the shielded 6904-ZZ runs with less friction.

**What is the SKF equivalent of 6904-2RS?**
SKF writes it 6904-2RSH; FAG 6904-2RSR, NSK 6904DDU, NTN 6904LLU and Koyo 6904-2RS. Check the maker's catalogue for the exact seal type.

**What does the number 6904 mean?**
6 is the deep groove ball bearing type, 9 is the thin-section dimension series, and 04 × 5 = 20 mm (from 04 up, multiply by 5).

**Which bearings have the same bore as 6904?**
6804, 6004, 6204, 6304 also have a 20 mm bore, with different outside diameters and widths.

Source page: https://machinistcharts.com/bearing/6904/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)