How to Identify Bearing Types by Their Part Numbers
When buying bearings, you’ve probably noticed long strings of letters and numbers on every product box or datasheet. While they might seem cryptic, these part numbers—or bearing codes—hold the key to understanding exactly what type of bearing you’re dealing with.
Learning how to decode these part numbers can help you:
Select the right bearing for your application
Save time during replacements
Avoid costly mistakes due to mismatched parts
In this article, we’ll show you how to read bearing numbers and what each section means.
Need bearings urgently? Visit our online store at Rodavictoria USA, email us at info@rdvbearings.com, or call us at +1 (954) 530-1454. We’ll help you find exactly what you need!
✅ Why Do Bearings Have Part Numbers?
Manufacturers like KOYO, SKF, NTN, and others follow standardized systems for bearing codes. These codes help:
Identify bearing type (e.g. deep groove ball, roller, needle)
Describe sealing type (rubber seals, shields, etc.)
Note precision level or special features
Once you learn the logic behind these numbers, it becomes much easier to find the right bearing for any machinery or project.
✅ The Basic Structure of Bearing Part Numbers
Let’s break down a typical bearing number:
Example: 6303 2RS C3
Here’s what each part means:
1. Bearing Series (First Digit or Two)
The first 1–2 digits show the bearing type or series:
6 → Deep Groove Ball Bearing
7 → Single Row Angular Contact Ball Bearing
2 → Spherical Roller Bearing
3 → Tapered Roller Bearing
So in 6303, the “6” means it’s a deep groove ball bearing.
2. Dimension Series (Next Digit)
The next digit indicates bearing robustness (the series):
Light, Medium, Heavy
For example:
0 → Extra light
2 → Light
3 → Medium
In 6303, the “3” refers to a medium series bearing.
3. Bore Size (Last Two Digits)
The last two numbers (usually multiplied by 5) give the inner diameter (ID) in millimeters.
Examples:
“03” → 3 x 5 = 15 mm bore
“04” → 4 x 5 = 20 mm bore
“10” → 10 x 5 = 50 mm bore
Thus, in 6303, “03” means a 17 mm bore (this is one exception where 03 = 17 mm instead of 15 mm).
4. Suffixes and Prefixes
Suffixes tell you about:
Seal type:
2RS = Two rubber seals
ZZ = Two metal shields
Clearance:
C3 = Greater internal clearance than standard
Precision:
P5 = Higher precision
Special features:
NR = Snap ring groove
M = Machined brass cage
In our example 6303 2RS C3:
2RS → Sealed on both sides with rubber seals
C3 → Greater internal clearance for higher speeds or temperature changes
✅ Quick Reference Table
Code
Meaning
2RS
Rubber seals both sides
ZZ
Metal shields both sides
NR
Snap ring groove
C3
Increased internal clearance
P5
High precision
M
Brass cage
✅ Why It Matters
Understanding bearing numbers helps you: ✅ Avoid incorrect replacements ✅ Save time identifying parts ✅ Communicate effectively with suppliers ✅ Order the right product confidently
✅ Need Help Identifying Your Bearing?
Still confused by your bearing code? Don’t worry—we’re here to help.
At Rodavictoria USA, we carry a wide range of bearings, pillow blocks, and oil seals, and our team of experts is ready to help you identify and choose the perfect product for your needs.
Empower yourself to decode bearing numbers—and keep your machines running smoothly.
