Bearing Size Chart: 5 Easy ID, OD & Width Tips

Choosing the correct bearing is essential for the reliable operation of motors, pumps, gearboxes, conveyors, fans, agricultural machinery and many other industrial machines. One of the easiest ways to identify the correct bearing is by using a bearing size chart.

A bearing size chart normally provides three primary dimensions:

• Bearing ID (d) – Bore Diameter
• Bearing OD (D) – Outside Diameter
• Bearing Width (B)

For example, a standard 6205 bearing has a 25 mm bore, 52 mm outside diameter and 15 mm width. These dimensions are important when checking whether the bearing will correctly fit the shaft and housing.

What Is a Bearing Size Chart?

A bearing size chart is a reference table that shows the standardized dimensions and, depending on the manufacturer, additional specifications of different bearings.

The most important dimensions are:

1. ID – Inside Diameter

The ID, also called the bore diameter, is the diameter of the hole in the center of the bearing. It determines the shaft size that the bearing is designed to fit.

For example:

• 6201 = 12 mm bore
• 6202 = 15 mm bore
• 6203 = 17 mm bore
• 6204 = 20 mm bore
• 6205 = 25 mm bore

2. OD – Outside Diameter

The OD is the outside diameter of the bearing’s outer ring. It is particularly important because the bearing must fit correctly inside the machine’s housing.

For example:

• 6203 has an OD of 40 mm
• 6204 has an OD of 47 mm
• 6205 has an OD of 52 mm
• 6206 has an OD of 62 mm

3. Width

Bearing width is the overall axial thickness of the bearing.

For example:

• 6203 = 12 mm wide
• 6204 = 14 mm wide
• 6205 = 15 mm wide
• 6206 = 16 mm wide

Therefore, a bearing specification such as:

6205 = 25 × 52 × 15 mm

means:

25 mm ID × 52 mm OD × 15 mm Width.

Standard Bearing Size Chart – 6200 Series

The 6200 series is one of the most commonly encountered families of single-row deep groove ball bearings. The following dimensions are based on SKF published dimensional data.

Bearing Number	ID / Bore (mm)	OD (mm)	Width (mm)
6200	10	30	9
6201	12	32	10
6202	15	35	11
6203	17	40	12
6204	20	47	14
6205	25	52	15
6206	30	62	16
6207	35	72	17
6208	40	80	18
6209	45	85	19
6210	50	90	20
6211	55	100	21
6212	60	110	22
6213	65	120	23
6214	70	125	24
6215	75	130	25
6216	80	140	25
6217	85	150	28
6218	90	160	30
6219	95	170	32
6220	100	180	34

The same dimensional relationship can also be seen in SKF’s published 6200-series bearing documentation.

How to Read a Bearing Size

Understanding bearing numbers can make bearing selection much easier.

Consider: 6205

The basic bearing number is 6205. The first two digits generally identify the bearing series/design. The final two digits identify the bore size. For standard metric bearings with bore codes from 04 upward, the bore is commonly obtained by multiplying the last two digits by 5.

For example:

05 × 5 = 25 mm

Therefore:

6205 = 25 mm bore

However, this rule has important exceptions for smaller bore codes such as 00, 01, 02 and 03. Common examples are:

Bore Code	Bore Diameter
00	10 mm
01	12 mm
02	15 mm
03	17 mm
04	20 mm
05	25 mm
06	30 mm
07	35 mm
08	40 mm
09	45 mm
10	50 mm

This is why 6201 does not mean 5 mm bore. Its standard bore is 12 mm.

SKF’s 6201 product specification, for example, lists a 12 mm bore, 32 mm outside diameter and 10 mm width.

Bearing Dimensions: ID vs OD vs Width

Three measurements should always be checked before ordering a replacement bearing.

ID – Shaft Measurement

The bearing’s ID must correspond to the shaft diameter and the required fit.

For example, if a shaft is designed for a 25 mm bearing bore, a 6205 may be appropriate because its nominal bore is 25 mm.

OD – Housing Measurement

The outer diameter must fit the housing bore.

For a 6205:

OD = 52 mm

Therefore, the machine housing must be designed around the required 52 mm bearing outside diameter and the appropriate tolerance/fit.

Width – Axial Space

The bearing must also fit within the available axial space.

A 6205 has a width of: 15 mm

If the machine requires a bearing with a different width, simply matching the ID and OD may not be enough.

Real Example: Selecting a 6205 Bearing

Suppose a factory machine has the following existing bearing:

• Shaft diameter = 25 mm
• Housing bore = approximately 52 mm
• Available bearing width = 15 mm

You check a bearing size chart. The 6205 bearing dimensions are:

ID = 25 mm , OD = 52 mm, Width = 15 mm

Therefore: 6205 = 25 × 52 × 15 mm

SKF’s published data confirms these nominal dimensions. This makes 6205 a dimensional match. However, dimensional compatibility is only the first step.

You should also check:

• Radial load
• Axial load
• Speed
• Temperature
• Lubrication
• Sealing
• Internal clearance
• Mounting arrangement
• Required bearing life

A bearing should never be selected only because its ID, OD and width match.

Real Industrial Example: Electric Motor

Consider a small industrial electric motor using a deep groove ball bearing. Suppose the motor shaft is designed for a 35 mm bearing bore. From the 6200 bearing size chart:

6207 = 35 × 72 × 17 mm

Therefore:

• Bore = 35 mm
• Outside diameter = 72 mm
• Width = 17 mm

SKF’s published 6207 data lists these dimensions and also provides load-rating and speed information for its bearing variants. But imagine that the original motor bearing is actually a 6207-2RS1.

The 6207 identifies the basic bearing size, while 2RS1 identifies the sealing configuration used by that manufacturer. So:

6207 → basic bearing size

2RS1 → sealing designation

The dimensional size remains:

35 × 72 × 17 mm

This is an important distinction when replacing bearings.

Bearing Size Chart for Common 6000 Series Bearings

The 6000 series is another common family of deep groove ball bearings.

Some commonly used sizes include:

Bearing	Typical ID	Typical OD	Typical Width
6000	10 mm	26 mm	8 mm
6001	12 mm	28 mm	8 mm
6002	15 mm	32 mm	9 mm
6003	17 mm	35 mm	10 mm
6004	20 mm	42 mm	12 mm
6005	25 mm	47 mm	12 mm
6006	30 mm	55 mm	13 mm
6007	35 mm	62 mm	14 mm
6008	40 mm	68 mm	15 mm

One important point is that bearings having the same bore do not necessarily have the same OD or width.

For example, a 25 mm bore can appear in different bearing series.

A 6205 is:

25 × 52 × 15 mm

while a 6005 is:

25 × 47 × 12 mm

Therefore, selecting a bearing based only on shaft diameter can result in the wrong bearing.

Why Bearing Series Matters ?

Bearing series controls the general cross-sectional size of the bearing.

For the same bore diameter, different series can have different outside diameters and widths.

For example, consider a 25 mm bore:

6005

25 × 47 × 12 mm

6205

25 × 52 × 15 mm

Both have:

25 mm ID

But their OD and width are different.

This means they are not automatically interchangeable. The housing and available axial space may be designed specifically for one series. This is one of the most common mistakes when selecting replacement bearings.

Bearing Size Chart for 6300 Series

The 6300 series is generally heavier than the 6200 series for comparable bore sizes.

Common examples include:

Bearing	ID (mm)	OD (mm)	Width (mm)
6300	10	35	11
6301	12	37	12
6302	15	42	13
6303	17	47	14
6304	20	52	15
6305	25	62	17
6306	30	72	19
6307	35	80	21
6308	40	90	23
6309	45	100	25
6310	50	110	27

These examples demonstrate why the bearing series should always be considered along with the bore.

For example:

6205 = 25 × 52 × 15 mm

whereas:

6305 = 25 × 62 × 17 mm

Both have a 25 mm bore, but the 6305 is significantly larger externally.

How to Choose the Correct Bearing Size

Use the following step-by-step method.

Step 1: Measure the Shaft

Measure the shaft diameter using a calibrated vernier caliper or micrometer. Suppose the shaft measures approximately: 25 mm

Do not immediately order a bearing based only on this measurement.

Step 2: Measure the Housing

Measure the housing bore. Suppose it is approximately: 52 mm

Now you have:

ID = 25 mm

OD = 52 mm

Step 3: Measure Available Width

Suppose the available axial space is: 15 mm

You now have: 25 × 52 × 15 mm

Search the bearing size chart. A standard 6205 matches: 25 × 52 × 15 mm

Step 4: Check Bearing Type

A 6205 is a single-row deep groove ball bearing. But your application may require:

• Deep groove ball bearing
• Angular contact bearing
• Tapered roller bearing
• Cylindrical roller bearing
• Spherical roller bearing
• Needle bearing
• Thrust bearing

Therefore, dimensions alone do not determine the correct bearing type.

Step 5: Check Sealing

A bearing can be available in different sealing configurations. Common designations include:

Open bearing

2Z / ZZ – shielded bearing

2RS – rubber-sealed bearing

The exact designation and naming convention can vary by manufacturer.

SKF’s product listings, for example, show 6200-series variants such as 6205-2Z and 6205-2RS1 while retaining the same basic dimensional envelope for the bearing size.

What Does C3 Mean in a Bearing?

Another important specification is internal clearance.

A bearing marked: 6205-2RS-C3

generally indicates:

• 6205 = bearing size
• 2RS = rubber sealing configuration
• C3 = greater-than-normal internal radial clearance

C3 clearance can be useful in applications where operating temperature, interference fits or other conditions require additional internal clearance. However, C3 should not automatically be considered “better” than normal clearance. The correct clearance depends on the application.

Bearing Size Is Not the Same as Bearing Capacity

Two bearings can have similar dimensions but different load capacities. For example, SKF’s published data for different bearing series includes basic dynamic and static load ratings along with speed information. Therefore, when choosing a bearing, consider both:

Dimensional compatibility and Performance compatibility

A bearing that physically fits may still fail prematurely if it is overloaded or operated outside its appropriate speed, temperature or lubrication conditions.

Example: Why ID Alone Can Mislead You ?

Suppose you need a bearing for a 25 mm shaft. You might find:

6005, 6205, 6305

All three can have a 25 mm bore, but their dimensions differ.

Bearing	ID	OD	Width
6005	25 mm	47 mm	12 mm
6205	25 mm	52 mm	15 mm
6305	25 mm	62 mm	17 mm

Therefore, if the machine housing is designed for a 52 mm OD, a 6005 or 6305 would not be a direct dimensional replacement for a 6205. This example shows why a complete bearing size chart is more useful than simply searching for a bearing by shaft diameter.

Metric Bearing vs Inch Bearing Sizes

Bearings are available in metric and inch-based dimensions. Metric bearings are commonly specified in millimetres.

For example:

6205 = 25 × 52 × 15 mm

Some bearing families use inch bore dimensions and different designation systems. When replacing a bearing, verify whether the original machine uses:

• Metric bearing
• Inch bearing
• Special bore
• Tapered bore
• Adapter sleeve arrangement

Never assume that a similar-looking metric bearing is interchangeable with an inch bearing.

How to Measure an Old Bearing

If the bearing number is unreadable, you can identify it by measuring its dimensions. Take three measurements:

Measurement 1 – Bore

Measure the center hole.

Example: 25 mm

Measurement 2 – Outside Diameter

Measure across the outside ring.

Example: 52 mm

Measurement 3 – Width

Measure the thickness.

Example: 15 mm

You now have: 25 × 52 × 15 mm

Search a reliable bearing catalogue using these dimensions. If the result corresponds to 6205, verify the bearing type and application before purchasing.

Why Manufacturer Catalogue Data Is Important

Online marketplaces often contain incomplete or inconsistent product descriptions. A reliable bearing catalogue can provide:

• Bore diameter
• Outside diameter
• Width
• Load rating
• Speed rating
• Clearance
• Seal/shield information
• Material
• Cage type
• Temperature information
• Lubrication details

SKF’s online marketplace, for example, publishes detailed dimensions for individual bearing products. Its 6201 listing specifies a 12 mm bore, 32 mm OD and 10 mm width. For technical applications, manufacturer catalogue data should be preferred over an unverified seller listing.

Common Bearing Size Mistakes

Mistake 1: Choosing Only by ID	A 25 mm shaft does not automatically mean every 25 mm bore bearing will fit. Check OD and width.
Mistake 2: Ignoring Bearing Series	6005, 6205 and 6305 have the same 25 mm bore but different dimensions.
Mistake 3: Ignoring Seals	Open, shielded and sealed bearings have different application characteristics.
Mistake 4: Ignoring Clearance	Normal clearance and C3 clearance are not interchangeable in every application.
Mistake 5: Ignoring Load	A dimensionally correct bearing may still be unsuitable for a high-load application.
Mistake 6: Ignoring Speed	High-speed applications require careful checking of bearing speed capability, lubrication and operating temperature.
Mistake 7: Measuring a Damaged Bearing Incorrectly	A worn bearing may no longer represent its original dimensions accurately. If possible, identify the original bearing number from the machine manual or manufacturer’s documentation.

Quick Bearing Size Identification Table

For common 6200-series bearings:

Bearing	Bore	OD	Width
6201	12 mm	32 mm	10 mm
6202	15 mm	35 mm	11 mm
6203	17 mm	40 mm	12 mm
6204	20 mm	47 mm	14 mm
6205	25 mm	52 mm	15 mm
6206	30 mm	62 mm	16 mm
6207	35 mm	72 mm	17 mm
6208	40 mm	80 mm	18 mm
6209	45 mm	85 mm	19 mm
6210	50 mm	90 mm	20 mm

This table is particularly useful when identifying commonly used deep groove ball bearings. SKF’s published data supports these nominal dimensions.

Bearing Size Chart: Real-World Selection Example

Imagine a conveyor roller in a small manufacturing plant. The technician removes the old bearing but the number is damaged.

Measurements are:

• Bore = 20 mm
• OD = 47 mm
• Width = 14 mm

Using a bearing size chart, the technician finds: 6204 = 20 × 47 × 14 mm

SKF’s catalogue data confirms these dimensions for the 6204 bearing. The technician should then verify:

1. Bearing type
2. Required load capacity
3. Operating speed
4. Sealing
5. Internal clearance
6. Lubrication
7. Operating temperature

If all specifications match the machine requirements, the 6204 can be considered as the replacement. This is a much safer process than simply searching online for “20 mm bearing.”

Bearing Size Chart and Bearing Life

Bearing size also influences load-carrying capacity, but bearing life depends on several factors.

For rolling bearings, calculated rating life is commonly based on the relationship between the basic dynamic load rating and equivalent dynamic bearing load.

For ball bearings, the commonly used basic rating-life relationship is:

L10 = (C/P)³

Where:

• L10 = basic rating life in million revolutions
• C = basic dynamic load rating
• P = equivalent dynamic bearing load

For roller bearings, the exponent is commonly: 10/3

Therefore: L10 = (C/P)^(10/3)

This demonstrates why simply selecting a larger bearing is not always the complete solution. Types of Load, speed, lubrication, contamination, mounting and operating conditions all affect actual service life.

How to Convert Bearing Life into Hours

If the calculated Bearing Life (L10 life) is expressed in million revolutions, approximate life in operating hours can be calculated using:

L10h = (L10 × 1,000,000) / (60 × n)

Where:

• L10h = life in hours
• L10 = life in million revolutions
• n = rotational speed in rpm

Example

Suppose: L10 = 100 million revolutions

and: n = 1,500 rpm

Then:

L10h = (100 × 1,000,000) / (60 × 1,500)

L10h ≈ 1,111 hours

This is a calculated rating life, not a guarantee that the bearing will physically last exactly that number of hours.

Bearing Size Chart: What Data Should You Record?

When creating your own bearing database or purchasing list, record at least:

Parameter	Example
Bearing Number	6205
Bearing Type	Deep Groove Ball Bearing
ID	25 mm
OD	52 mm
Width	15 mm
Seal	Open / 2Z / 2RS
Clearance	CN / C3
Material	Bearing Steel
Cage	Steel / Polyamide / Brass
Dynamic Load Rating	Manufacturer specific
Static Load Rating	Manufacturer specific
Speed	Manufacturer specific

This makes bearing selection much easier for maintenance teams and purchasing departments.

Conclusion

A bearing size chart is one of the most useful tools for identifying and selecting the correct bearing. The three most important dimensions are ID, OD and width.

However, correct bearing selection involves more than dimensions. You should also verify the bearing series, load capacity, operating speed, internal clearance, sealing, lubrication, temperature and application requirements.

For maintenance and replacement work, the best approach is:

Measure → Identify → Check Size → Check Bearing Type → Verify Load & Speed → Check Seal/Clearance → Select the Correct Bearing.

A properly selected bearing can improve machine reliability, reduce unexpected downtime and help prevent premature bearing failure.

For technicians, engineers, maintenance professionals and industrial buyers, keeping a bearing size chart available is therefore a simple but extremely valuable practice.

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