Bearing designation

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Bearing designation tree.png

To identify a bearing, it’s assigned a standardized code referred to as a designation. The designation is made up of one to three parts;

  • Prefix
  • Basic designation
  • Suffix

Prefixes and suffixes, which provide additional information to the designation, are not always included.

Basic designation

A basic designation contains three to five digits that always represent these three pieces of information:

  • Bearing type,
  • Dimension series, and
  • Bore size (inner diameter).

Note: the Bearing type and Dimension series put together is called Bearing series.

Let’s take the following three designations as examples

Basic bearing designation examples.png
  • 626 (3 digit designation)
  • 6305 (4 digit designation)
  • 62103 (5 digit designation)


  • The first digit always tells us the Bearing type (6 = Single row deep ball groove bearing.)
  • The second digit (2) tells us the Dimension series (2 = Light).
  • In a three digit designation, the third digit (6) tells us the Bore size in mm. So in this case, the Bore diameter is 6 mm.


  • Again, the first digit tells us the Bearing Type (6 = Single row deep ball groove bearing.)
  • The second digit (3) tells us the Bearing series (3 = Medium.)
  • The third and fourth digit (05) tells us the Bore size (05 = 25 mm.)


  • The first digit is for Bearing type.
  • The second and third digit tells us the Dimension series where
    • the second digit (2) is the width code and
    • the third digit (1) is the diameter series
  • The fourth and fifth digits (03) tells us the bearing Bore size (03 = 17 mm.)

Prefixes and suffixes

A bearing code can also be made longer to include additional information such as;

  • Shield code
  • Contact angle code
  • Matched pair or stack code
  • Internal design code
  • External configuration code
  • Bearing ring shape code
  • Internal clearance code
  • Tolerance class code

Codes and their meanings are listed in the section Code tables.

Additional designation examples

Here are some examples what bearing designations can look like. The meaning of the codes is found in section Code tables.

Bearing designation examples.png

Code tables

The tables below provide the symbols that can make up a bearing designation along with their respective meanings.

Prefix codes

Prefix Code Meaning
K Cage with roller elements
L Removable bearing ring
R Ring with roller set
S Roll body of stainless steel
W Stainless steel deep groove ball bearing
H, LM Tapered Roller Bearings-Inch
HJ, IR Needle Roller Bearings-Inchstvle
K Needle Roller Bearings-Metric
N, NJ, NU, NUP Cvlindrical Roller Bearings-Metric
NA, NAO Needle Roller Bearings with Inner Rings-Metric
NK, RNA Needle Roller Bearings without Inner Rinos-Metric
NN Super Precision Cylindrical Roller Bearings

Bearing type codes

Bearing type code Meaning
1 Self aligning Ball Bearing
2 Spherical Roller Bearing
3 Double row Angular contact Ball bearing
4 Double row Ball Bearing
5 Thrust Ball bearing
6 Single row deep groove ball bearing
7 Single row angular contact bearing
8 Felt sealbearing
32 / T Tapered Roller Bearing
R Inch Bearing
N Cylindrical roller bearing
NN Double row roller bearing
NA Needle roller bearing
BK Needle roller bearing with closed end (Drawncup)
HK Needle roller bearing with openends (Drawncup)
C GARB roller bearings
K Needle roller and cage thrust assembly
QJ Four-point contact ball bearings
BH Angular cont-act (15°)
BIH Angular contact (15°)inch series
BA Angular contact (25° or 29°)
BT Angular contact (35"-40")
BY Angular contact (35°-40")
BO Angular contact, double row, radial, non- filling slot
BZ Angular contact,split inner ring
BE Bell bearin& double row,angular contact,filling slot (maximum capacity)
BG Ball bearing, double row, angular contact,non-filling slot
BF Ball bearing,double row, radial,fill ng slot (maximum capacity)
BK Ball bearing, double row, radial,non-filling slot
BM Ball bearing, single row separable
8L Ball bearing, single row, radial,filling slot (maximum capacity)
BC Ball bearing, single row, radial,non-filling slot (Conrad)
BIC Bell bearing, single row, radial,non-filling slot,inch series (Conrad)
BS Self-aligning ball bearing
R Cylindrical roller
S Self-aligning spherical roller
T Thrust ball or roller

Dimension series codes

Dimension series code Meaning
0 Extra light
1 Extra light thrust
2 Light
3 Medium
4 Heavy
8 Extra thin section
9 Very thin section

Bore size codes

From code 04 and onward, the code multiplied by 5 equals the bore size in millimeters;

04x5 = 20 mm,

05x5 = 25 mm,

06x5 = 30 mm and so on.

Bore size code Bore size in millimeters
00 10
01 12
02 15
03 17
04 20
05 25
06 30
07 35
08 40
09 45

Shielding or sealing code

Shielding orsealing code Meaning
Code Description
z One side shielded
zz Both sides shielded
RS One side sealed
2RS Both sides sealed
v One side non contact seal
vv Both sides non contact seal
DDU Both sides contact seals
NR Snap ring and groove
M Brass cage

Angular contact codes

Angular contact code for ball bearings Meaning
A 30°
AC 25°
B 40°
C 15°
CA 20°
E 35°

Angular contact code for Tapered roller bearings Meaning
B Less than 17°
C 20°
D 28° 30'
DJ 28° 48' 39"

Internal clearance codes

Internal Clearance code Meaning
C2  : Tight
C0 or CN  : Normal
C3  : Loose
C4  : Extra Loose
CM  : Radial internal clearance for electric motor use
/GL  : Light preload
/GN  : Normal preload
/GM  : Medium preload
/GH  : Heavy preload

Conditions when the machine is in operation Examples Optimal internal bearing clearance in C code
Significant shaft deflection Semi-floating wheel bearings in cars C5 or equivalent
Steam flow through hollow shaft or pressure rods exposed to high temperatures The drying part of paper machines; C3, C4;
Transport rollers in rolling mills C3
High impact loads and vibrations or both the inner and outer ring have a press fit Traction engines for trains C4;
Vibrating sieves C3, C4;
Hydraulic connector C4;
Gearboxes for tractors C4;
Loose fitting inner and outer rings Rolling pins for rolling mills C2 or similar
Low noise and no vibrations Small motors with special features C1, C2, CM
Setting to prevent significant shaft deflection Main spindle of lathes CC9, CC1

Cage type codes

Cage type code Meaning
x Manufacturer standard bearingcage
A Steel pressed (land guided)
J Steel pressed (ball guided)
F Steelor iron,machined
y Brass or bronze, pressed
B Brass or bronze, pressed (land guided)
K Brass or bronze, machined (land guided)
M Brass or bronze, machined (ball guided)
H Light alloy,machined
0 Non-metallic (land guided)
T Non-metallic (ball guided)
v Full complement bearingwithout cage

External configuration codes

External configuration code Meaning
No code Cylindrical inner ring bore
K Tapered inner ring bore, taper ratio 1:12
K30 Tapered inner ring bore, taper ratio 1:30
N With snap ring groove
NR With snap ring
D With oil hole
D1 Lubrication hole/lubrication groove
T Non-metallic (ball guided)
v Full complement bearing without cage

Internal design codes

Internal design codes Meaning
U Internationally interchangeable tapered roller bearings
R Noninternationally interchangeable tapered roller bearings
ST Low torque tapered roller bearings
HT High axial load use cylindrical roller bearings

Bearing arrangement codes

Bearing arrangement refers to how several bearings are arranged together to achieve characteristics in a product that are appropriate for the intended use or load condition. Details about bearing arrangement are found on this page: Bearing selection

Bearing arrangement code Meaning
DB Back-to-back arrangement
DF Face-to-face arrangement
DT Tandem arrangement
D2 Two matched, paired bearings
G Flush ground

Tolerance class codes

Tolerance class code Meaning
P6 JIS Class 6
P5 JIS Class 5
P4 JIS Class 4
P2 JIS Class 2
2 ABMA Class 2
3 ABMA Class 3
0 ABMA Class 0

Internal links

Bearing selection

OSE Bearing dimensioning calculator

Bearings 101