17 mm bore deep-groove ball bearing.
Bearing Size Converter
Convert common bearing numbers such as 608, 6001, 6203, 6205, and 6304 into bore, outside diameter, width, millimeters, and inches. Useful for motors, wheels, skate bearings, pulleys, tools, farm repairs, and replacement parts.
Convert a bearing number
Choose a common metric bearing code, or enter dimensions to find the closest matches.
6203 bearings are common in motors, mower wheels, alternators, pumps, and pulleys. Match seals, clearance, load rating, and speed before ordering.
How bearing numbers convert
Many common metric bearing numbers include a series and a bore code. In a 6203 bearing, “62” is the light-series deep-groove family and “03” means a 17 mm bore. For codes 04 and larger, multiply the last two digits by 5 to estimate bore size in millimeters.
Suffixes usually describe construction details. For example, 6203-2RS and 6203-ZZ normally share the same 17 × 40 × 12 mm dimensions, but one has rubber seals and the other has metal shields.
Measure before replacing a bearing
Use calipers to measure the inside diameter, outside diameter, and width. Old bearings can be dirty, worn, or unmarked, so compare all three measurements rather than relying on a partial code.
This converter covers common radial ball bearings. Tapered roller bearings, needle bearings, thrust bearings, and specialty automotive bearings may use different numbering systems.
Common bearing size chart
| Bearing | Bore | Outside diameter | Width | Common notes |
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Bearing size FAQ
What size is a 608 bearing?
A common 608 skate bearing is 8 mm bore, 22 mm outside diameter, and 7 mm wide. It is often used in skateboards, scooters, inline skates, and small wheels.
What size is a 6205 bearing?
A standard 6205 bearing is 25 mm bore, 52 mm outside diameter, and 15 mm wide, which is about 0.984 in × 2.047 in × 0.591 in.
Can I replace a 2RS bearing with a ZZ bearing?
Only if the application allows it. 2RS rubber seals usually protect better from dust and moisture, while ZZ metal shields can have less drag. Keep the same dimensions and check the environment, speed, and manufacturer recommendation.