Bearing Size Chart: Ball, Roller & Thrust Bearing Dimensions

A bearing size chart matches a bearing number to its nominal bore diameter (d), outside diameter (D), and width (B) or overall height (T). For example, a 6205 measures 25 × 52 × 15 mm. Use all three dimensions to narrow down a replacement, then confirm the bearing type, seals, clearance, load ratings, and mounting details.

How to use this chart: All dimensions below are in millimeters. The tables cover 6200–6210 and 6300–6310 deep groove ball bearings, NU204–NU212 cylindrical roller bearings, and 51100–51112 thrust ball bearings. They are a dimensional reference, not a complete interchange or load-capacity catalog.

Common Bearing Sizes: Quick Reference

Start here for several common deep groove ball bearing sizes. If only the shaft diameter is known, check the housing bore and available width before choosing a series.

Ball Bearing Size Chart

Single-row deep groove ball bearings support radial loads and can also accommodate axial loads in both directions within their design limits. The 6200 and 6300 families share many bore sizes, but their outside diameters and widths differ.

For the smaller cross-section 6000–6010 family, use our 6000 series bearing size chart. It includes the dimensions and a comparison of 6006 and 6206.

6200 Series: 6200–6210 Dimensions

For seals, C3 clearance, and replacement checks on a 30 mm bore example, see the 6206 bearing dimensions and equivalents guide.

6300 Series: 6300–6310 Dimensions

6205 vs. 6305: The Same Bore Does Not Mean the Same Fit

A 6205 is 25 × 52 × 15 mm; a 6305 is 25 × 62 × 17 mm. Both have a 25 mm bore, but the 6305 is 10 mm larger in outside diameter and 2 mm wider. It is not a direct replacement in a housing designed for a 6205.

Changing series requires checking the housing, axial space, shaft shoulders, fillet clearances, and bearing arrangement. A larger bearing should not be treated as the automatic solution to repeated failures; lubrication, contamination, alignment, and operating clearance also need investigation.

Once the dimensions are confirmed, browse our deep groove ball bearings for the required configuration.

Roller Bearing Size Chart

The table below covers NU-series cylindrical roller bearings. NU designs have two flanges on the outer ring and no flanges on the inner ring. They carry radial loads and allow relative axial displacement between the rings in both directions. A separate locating arrangement is needed when the shaft must be positioned axially.

NU200 Series: NU204–NU212 Dimensions

For example, NU206 and 6206 both have a 30 × 62 × 16 mm envelope. Their internal geometry and axial locating behavior are different, so matching these dimensions does not establish interchangeability.

For bearings with slender rollers and different ring arrangements, use the needle roller bearing size chart. Check whether the listed bore is a ring bore or a roller-envelope dimension before matching a shaft.

For self-aligning roller bearing dimensions, see the spherical roller bearing size chart.

For tapered roller bearing assemblies, use the taper roller bearing size chart. Match the complete cone-and-cup designation and assembled width T; the widths of the individual rings are separate dimensions.

Thrust Bearing Size Chart

The 51100 family consists of single-direction thrust ball bearings with flat washers. They support axial load in one direction and are not designed to carry radial load. In this table, d is the shaft-washer bore, D is the housing-washer outside diameter, and T is the overall assembled height.

51100 Series: 51100–51112 Dimensions

Measure the complete assembly, including both washers and the ball-and-cage assembly. Measuring one washer gives neither the total height nor all the information needed to identify the bearing.

Load checks still matter: For a rotating thrust bearing, check rating life using its axial dynamic rating, then check static safety, minimum axial load, and speed. The static rating alone does not determine whether the bearing will work. Reversing axial loads require an arrangement designed to support both directions.

How to Measure Bearing Size

For an initial identification, remove dirt and burrs and measure an accessible, undamaged bearing with calipers. Record dimensions in the order d × D × B, or d × D × T for a thrust bearing. Calipers help identify a nominal size; they do not verify precision shaft or housing fits.

Take readings in more than one position. Wear, corrosion, coatings, temperature, and measurement technique can shift the result. Use a micrometer and suitable bore-measuring equipment when checking seat tolerances or investigating an out-of-round shaft or housing.

For a complete housed unit, the bearing envelope is only part of the measurement. Use the pillow block bearing size chart to check shaft size, shaft center height, and mounting-bolt spacing.

Find a Bearing by ID, OD, and Width

If the marking is unreadable, use the dimensions as a shortlist rather than a final part number:

1. Record bore, outside diameter, and width or assembled height. Keep the measurement units consistent.

2. Identify the bearing construction: ball, cylindrical roller, tapered roller, or thrust. Look for flanges, snap-ring grooves, extended rings, and other locating features.

3. Compare all three dimensions with a catalog row. Two matching dimensions are not enough.

4. Confirm the full designation and application requirements before ordering. Seals, clearance, precision, cage, material, and lubrication can differ within one nominal size.

Lookup example: A 30 mm bore alone could correspond to 6206, 6306, or NU206. The 6206 and NU206 are both 30 × 62 × 16 mm; the 6306 is 30 × 72 × 19 mm. Dimensions narrow the search, while construction determines the bearing type.

When the complete designation is known, our bearing cross reference provides manufacturer interchange references. Verify the proposed alternative against its own drawing and specification.

Bearing Number Decoder: Bore Codes and Suffixes

For many standard metric bearings in the families listed here, the last two digits identify the bore. The first four codes are exceptions to the multiplication rule:

For the 04–12 codes used in these tables, multiply the code by 5 to obtain the bore in millimeters. For example, 07 × 5 = 35 mm. Do not apply this rule to every bearing number: miniature bearings, slash designations, inch series, and special designs have other conventions.

What 2RS, ZZ, and C3 Tell You

For standard deep groove ball bearing variants, seals, shields, and C3 clearance usually do not change the nominal d × D × B dimensions. They can change friction, lubrication requirements, operating clearance, and permissible speed. Check the actual product drawing when a special seal or locating feature is present.

For a fuller explanation of chart columns and designation rules, read how to read a bearing size chart.

Metric vs. Inch Bearing Sizes

These tables use metric dimensions. Inch-series bearings require their own dimensional references; converting a metric dimension into inches does not create an interchangeable inch bearing. The exact conversion is 1 inch = 25.4 mm.

For example, a 1-inch shaft is nominally 25.4 mm, which is 0.4 mm larger than the 25 mm bore of a 6205. Those sizes are not interchangeable. If a measurement falls between the metric values listed here, check the units, measurement condition, and possible special or inch-series designation.

What to Check Beyond Bearing Dimensions

A size match confirms the nominal envelope, not the complete mounting fit or operating performance. Before approving a replacement, check these items:

To check a specific 25 × 52 × 15 mm configuration, see the 6205 product specifications.

Dimensional Standards and Data Scope

ISO 15 provides a general plan for preferred radial bearing boundary dimensions. ISO 492 addresses radial bearing dimensional and geometrical tolerances; ISO 355 covers metric tapered roller bearing boundary dimensions and series designations; ISO 104 covers thrust bearing boundary dimensions.

The four series tables list nominal envelope dimensions cross-checked against manufacturer dimensional data. They do not specify tolerances, shoulder dimensions, chamfers, or every available bearing variant. Use the selected product’s current drawing and data sheet for a final engineering decision.

Dimension references: JTEKT Ball & Roller Bearings, bearing specification tables, and LILY individual product dimension sheets. These references are used for nominal dimensions only; performance ratings must come from the exact product being selected.

Frequently Asked Questions

What is the difference between a 6205 and a 6305 bearing?

A 6205 measures 25 × 52 × 15 mm; a 6305 measures 25 × 62 × 17 mm. They share a 25 mm bore, but the 6305 is 10 mm larger in outside diameter and 2 mm wider. They are not direct replacements in the same housing.

How do I identify a bearing if its number is unreadable?

Measure the bore, outside diameter, and width, then compare all three with the size chart. Matching dimensions narrows the candidates but does not uniquely identify the bearing. Also check its construction, seals, grooves, flanges, and extended rings.

If identification remains uncertain, send clear photographs of both faces, any remaining markings, and your measurements. Include the machine application, operating speed, load direction, and any observed damage.

Why is my measured bearing size slightly different from the nominal size?

Catalog dimensions are nominal. Manufacturing tolerances, wear, contamination, temperature, and instrument accuracy can affect a reading. Compare the measured value with the specified tolerance for that bearing; do not round a large discrepancy away.

How do I calculate bearing life from the load rating?

For ball bearings, the basic rating-life equation is L10 = (C/P)³, where L10 is expressed in millions of revolutions, C is the basic dynamic load rating, and P is the equivalent dynamic bearing load. Use the same units for C and P. For roller bearings, the exponent is 10/3 instead of 3.

For constant speed n in rpm, convert to hours using L10h = [10⁶/(60n)] × L10. This basic fatigue-life estimate corresponds to 90% reliability for a population of otherwise identical bearings under the stated conditions; it is not a guaranteed service interval. Lubrication, contamination, installation, and other failure mechanisms also affect actual life.

Use the selected product’s ratings and the appropriate equivalent-load factors in our bearing life calculator.

Need help narrowing down a replacement? contact us with the dimensions, photographs, and operating details.