# 6311 bearing dimensions

A 6311 bearing is 55 mm bore × 120 mm outside diameter × 29 mm wide (2.165 × 4.724 × 1.142 in). The sealed version is 6311-2RS; the shielded version is 6311-ZZ.

## 6311 data

- Type: deep groove ball bearing, 63 series (medium)
- Bore d: 55 mm (2.1654 in)
- Outside diameter D: 120 mm (4.7244 in)
- Width B: 29 mm (1.1417 in)
- Bore code: 11 × 5 = 55 mm (from 04 up, multiply by 5)
- Sealed: 6311-2RS; shielded: 6311-ZZ; open: 6311

## Designations by maker

| Maker | Sealed | Shielded |
|---|---|---|
| SKF | 6311-2RSH | 6311-2Z |
| FAG (Schaeffler) | 6311-2RSR | 6311-2ZR |
| NSK | 6311DDU | 6311ZZ |
| NTN | 6311LLU | 6311ZZ |
| Koyo (JTEKT) | 6311-2RS | 6311ZZ |
| Timken | 6311-2RS | see catalogue |

## Same 55 mm bore, other series

| Bearing | Series | OD mm | Width mm |
|---|---|---|---|
| 6011 | extra-light | 90 | 18 |
| 6211 | light | 100 | 21 |
| 6311 | medium | 120 | 29 |


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

## FAQ

**What size is a 6311 bearing?**
55 mm bore, 120 mm outside diameter and 29 mm wide, which is 2.165 × 4.724 × 1.142 in.

**What does 2RS mean on a 6311 bearing?**
6311-2RS has rubber contact seals on both sides. 6311-ZZ (also written 6311-2Z) has metal shields on both sides. Both have the same 55 × 120 × 29 mm dimensions.

**Is 6311-2RS the same as 6311-ZZ?**
They are the same size and interchangeable in a housing. The sealed 6311-2RS keeps out fine dirt and water better; the shielded 6311-ZZ runs with less friction.

**What is the SKF equivalent of 6311-2RS?**
SKF writes it 6311-2RSH; FAG 6311-2RSR, NSK 6311DDU, NTN 6311LLU and Koyo 6311-2RS. Check the maker's catalogue for the exact seal type.

**What does the number 6311 mean?**
6 is the deep groove ball bearing type, 3 is the medium dimension series, and 11 × 5 = 55 mm (from 04 up, multiply by 5).

**Which bearings have the same bore as 6311?**
6011, 6211 also have a 55 mm bore, with different outside diameters and widths.

Source page: https://machinistcharts.com/bearing/6311/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)