21 mm outside diameter bearing chart: models, dimensions & brands
Compare actual catalogue candidates for 21 mm outside diameter. Retain the remaining dimensions, complete designation and original construction before making a selection.
On this page6 sections ⌄
21 mm outside diameter: what this result means
The shortlist fixes 21 mm outside diameter. Bore and width still need to be chosen.
A bore is not the diameter of a loose precision ball. Complete bearings, inserts and other catalogue components can have different functions even where the recorded dimensions match. Keep the original product type visible when making a shortlist.
| Requested dimension | Millimetres | Inches | Selection meaning |
|---|---|---|---|
| Outside diameter D | 21 mm | 0.826772 in | Nominal catalogue value, not a shaft/housing fit tolerance |
Inch conversions use 25.4 mm per inch and are displayed to six decimals. A converted metric dimension does not make a bearing an inch-series design.
Are your measurements in millimetres or inches?
The chart on this page uses millimetres. An unlabelled search such as 21 does not tell us which unit was measured. Choose the unit for those same numbers before opening a different catalogue lookup.
Outside diameter D: 21 mm
Search 21 mmConversion and reinterpretation are different
Same physical size, another unit: divide a dimension in millimetres by 25.4 to express it in inches. The bearing does not change.
The original numbers were inches: multiply those numbers by 25.4 to obtain the millimetre values used in the catalogue. For the numbers on this page, that means 533.4 mm, not 21 mm.
One inch is exactly 25.4 millimetres. Displayed values are rounded to six decimals; rounding is not a manufacturing tolerance. Confirm the measured axes and the complete bearing construction before comparing models.
The unit choice updates the lookup immediately. The main chart below remains the millimetre size in this page heading. A catalogue search can have no recorded match; that means no match in the available data, not that the size cannot exist. A loose precision ball has one diameter and is not a complete bearing d×D×width measurement.
Filter every recorded match for 21 mm outside diameter
Keep the known dimensions fixed while narrowing all 123 complete-dimension records in this snapshot. Read the full designation and original construction before opening a product record.
Ball-bearing searches: select Ball bearings to remove roller bearings and mounting components. The requested bore belongs to a complete bearing; this is not a loose precision-ball diameter chart.
Showing the first 24 of 123 records. Filters update immediately.
| Brand / full designation | Original product type | Recorded d×D×width (mm) | Closure | Clearance | Precision |
|---|---|---|---|---|---|
| INA3801-2Z-L091 | Angular contact ball bearing | 12×21×7 | Not reported | Not reported | Not reported |
| FAG61702>N | Deep groove ball bearing | 15×21×4 | Without — Not sealed | CN (Group N) — Normal internal clearance | PN — Normal (ISO 492:2023) |
| SKF61801 | Deep groove ball bearing | 12×21×5 | Without | CN | P6 |
| SKF61801-2RS1 | Deep groove ball bearing with seals or shields | 12×21×5 | Seal on both sides | CN | P6 |
| FAG61801-2RSR>N | Deep groove ball bearing | 12×21×5 | 2RSR — Contact seal on both sides | CN (Group N) — Normal internal clearance | PN — Normal (ISO 492:2023) |
| FAG61801-2RZ>N | Deep groove ball bearing | 12×21×5 | 2RZ — Non-contact seal on both sides | CN (Group N) — Normal internal clearance | PN — Normal (ISO 492:2023) |
| SKF61801-2Z | Deep groove ball bearing with seals or shields | 12×21×5 | Shield on both sides | CN | P6 |
| FAG61801>N | Deep groove ball bearing | 12×21×5 | Without — Not sealed | CN (Group N) — Normal internal clearance | PN — Normal (ISO 492:2023) |
| KOYO6702 | Deep groove ball bearing | 15×21×4 | Open | Not reported | Not reported |
| KOYO6702 2RS | Deep groove ball bearing | 15×21×4 | Contact sealed | Not reported | Not reported |
| KOYO6702 2RU | Deep groove ball bearing | 15×21×4 | Non-contact sealed | Not reported | Not reported |
| KOYO6702 ZZX | Deep groove ball bearing | 15×21×4 | Shielded ZZ | Not reported | Not reported |
| KOYO6801 | Deep groove ball bearing | 12×21×5 | Open | Not reported | Not reported |
| KOYO6801 2RD | Deep groove ball bearing | 12×21×5 | Extremely light contact sealed | Not reported | Not reported |
| KOYO6801 2RS | Deep groove ball bearing | 12×21×5 | Contact sealed | Not reported | Not reported |
| KOYO6801 2RU | Deep groove ball bearing | 12×21×5 | Non-contact sealed | Not reported | Not reported |
| KOYO6801 ZZ | Deep groove ball bearing | 12×21×5 | Shielded ZZ | Not reported | Not reported |
| SKF71801 ACD/HCP4 | Super-precision, high-capacity, single row angular contact ball bearing | 12×21×5 | Without | Not reported | Not reported |
| SKF71801 ACD/HCP4DGA | Matched set of two super-precision, high-capacity, D design, single row angular contact ball bearings | 12×21×10 | Without | Not reported | Not reported |
| SKF71801 ACD/P4 | Super-precision, high-capacity, single row angular contact ball bearing | 12×21×5 | Without | Not reported | Not reported |
| SKF71801 ACD/P4DBB | Matched set of two super-precision, high-capacity, D design, single row angular contact ball bearings | 12×21×10 | Without | Not reported | Not reported |
| SKF71801 ACD/P4DGB | Matched set of two super-precision, high-capacity, D design, single row angular contact ball bearings | 12×21×10 | Without | Not reported | Not reported |
| SKF71801 ACD/P4DGC | Matched set of two super-precision, high-capacity, D design, single row angular contact ball bearings | 12×21×10 | Without | Not reported | Not reported |
| SKF71801 ACD/P4QBCB | Matched set of four super-precision, high-capacity, D design, single row angular contact ball bearings | 12×21×20 | Without | Not reported | Not reported |
Open current catalogue for these dimensions →
Snapshot 2026-10-01. Counts describe the available records, not every bearing made. The original product type is retained. Matched sets, units, flanges, sleeves and tapered assemblies require their own drawing; a recorded width is not automatically a single radial-ring width B. Unreported properties remain unknown. Matching dimensions do not approve substitution.
Keep these dimensions and choose a brand
Choosing a brand opens the existing live filters immediately with the dimensional conditions retained. These are catalogue candidates, not interchange approvals.
How to narrow the shortlist
- Confirm which dimension was measured: bore d, outside D or axial width. Do not use a flange diameter as the bearing outside diameter.
- Measure the remaining boundary dimensions and preserve the original marking. A single known diameter usually identifies several different models.
- Select the required construction, seals, clearance and precision in the live results. An unreported field is still unknown.
- Check the exact product drawing, load ratings, speed and mounting requirements before considering a replacement.
Reference basis & data limits
Manufacturer terminology is retained in the product records. Technical reference basis: JTEKT Basic Bearing Knowledge (boundary dimensions, tolerance classes and lubrication); NSK Bearing ABCs (lubrication, designations and clearance); NTN technical FAQs (closure codes and component interchange); SKF rolling-bearing selection and maintenance references.
Selection workflows and catalogue grouping are BearingScope editorial aids. Verify the current drawing and application requirements before using a candidate. Missing database information is not converted into an assumed match.