Bearing Designations

5—Bearing Designations

Bearing designations (bearing numbers) are codes that provide information about the design of a bearing. The basic designation uses definitions specified by ISO/JIS, while the meanings of codes in the supplementary (auxiliary) designation may be unique to the bearing manufacturer.

Formulation of Designations

The designation of a rolling bearing indicates its type, boundary dimensions, dimensional and running accuracies, internal clearance, and other specifications. It consists of two parts:

Basic Designation:
A code indicating the bearing type and important dimensions.
The first part is called the bearing series. After the type code, dimensions are specified with one or two digits indicating width/height and diameter, though the width code is sometimes omitted. The series is followed by codes for bore number and contact angle.

Supplementary Designation:
A code indicating bearing specfications, including design, material, cage type, and so on.

Though usually indicated in full on packaging, bearing designations may be abbreviated or omitted on certain components or documentation. 

Listing of the order of codes within a bearing designation.

Radial Bearings: Basic Designations

Diagram of coding present in an example bearing designation.

Radial Bearings: Width and Diameter Series

Diagram of coding for the width and diameter series within a bearing designation.

Bearing Series Designations

Bearing TypeSeriesTypeDimensions
WidthDiameter
Single-row deep groove ball bearings68
69
60
62
63		6
6
6
6
6		（1）
（1）
（1）
（0）
（0）		8
9
0
2
3
Single-row angular contact ball bearings79
70
72
73		7
7
7
7		（1）
（1）
（0）
（0）		9
0
2
3
Self-aligning ball bearings12
13
22
23		1
1
（1）
（1）		（0）
（0）
2
2		（0）
（0）
2
2
Single-row cylindrical roller bearingsNU10
NU2
NU22
NU3
NU23
NU4		NU
NU
NU
NU
NU
NU		1
（0）
2
（0）
2
（0）		0
2
2
3
3
4
NJ2
NJ22
NJ3
NJ23
NJ4		NJ
NJ
NJ
NJ
NJ		（0）
2
（0）
2
（0）		2
2
3
3
4
NUP2
NUP22
NUP3
NUP23
NUP4		NUP
NUP
NUP
NUP
NUP		（0）
2
（0）
2
（0）		2
2
3
3
4
N10
N2
N3
N4		N
N
N
N		1
（0）
（0）
（0）		0
2
3
4
NF2
NF3
NF4		NF
NF
NF		（0）
（0）
（0）		2
3
4
Bearing TypeBearing SeriesTypeDimensions
Width/HeightDiameter
Double-row cylindrical roller bearingsNNU49
NN30		NNU
NN		4
3		9
0
Needle roller bearingsNA48
NA49
NA59
NA69		NA
NA
NA
NA		4
4
5
6		8
9
9
9
Tapered roller bearing329
320
330
331
302
322
332
303
323		3
3
3
3
3
3
3
3
3		2
2
3
3
0
2
3
0
2		9
0
0
1
2
2
2
3
3
Spherical roller bearings230
231
222
232
213(1)
223		2
2
2
2
2
2		3
3
2
3
0
2		0
1
2
2
3
3
Thrust ball bearings with flat back face511
512
513
514
522
523
524		5
5
5
5
5
5
5		1
1
1
1
2
2
2		1
2
3
4
2
3
4
Spherical roller thrust bearings292
293
294		2
2
2		9
9
9		2
3
4

Note (1) Bearing Series 213 would logically be 203, but customarily it is numbered 213.
Remarks Numbers in parentheses in the width column are usually omitted from the designation.

Ball Bearing Designations

Examples of designations and the codes used within for ball bearings.

Roller Bearing Designations

Examples of designations and the codes used within for roller bearings.

Radial Bearings: Boundary Dimensions

Radial ball/roller bearing

Diagram of various chamfers and dimensions in radial bearings.

Tapered roller bearing

Diagram of chamfers and dimensions for tapered roller bearings
What are boundary dimensions?

Boundary dimensions define the important external geometry of a bearing. They are:

  • Bearing bore d,
  • Bearing outer diameter D,
  • Bearing width (or inner ring width) B,
  • Outer ring width C,
  • Assembled width T, and
  • Main chamfer dimensions r, r1

These dimensions are crucial in mounting the bearing to the shaft or housing.
Boundary dimensions are specified by ISO, allowing standard products to be interchangeable.