What are the dimensions of a 6904 bearing?

Answer 20 × 37 × 9 mm

The 6904 is a deep-groove ball bearing: 20 mm bore, 37 mm outside diameter, 9 mm wide.

Change the numbers →

How it is worked out

Type6 → deep-groove ball bearing
Series69 → series 69 · thin-section · dimension series 19
Bore code04 → 04 × 5 = 20 mm

d = bore code × 5 mm (04+) · 00 = 10 · 01 = 12 · 02 = 15 · 03 = 17 mm

Worth knowing

In inches: 0.787 × 1.457 × 0.354 in. A metric bearing: inch-series bearings (R8, 1600…) do not fit the same shaft.
2RS · 2RS1 · 2RSH · DDU · LLU: Rubber seal on both sides, greased for life. Best against dirt and water, slightly more drag. The same bearing by brand: SKF 6904-2RSH or -2RS1, FAG 6904-2RSR, NSK 6904DDU, NTN 6904LLU.
ZZ · 2Z · 2ZR: Metal shield on both sides. Less friction and more speed than a seal, but not watertight. SKF 6904-2Z, FAG 6904-2ZR, NSK and NTN 6904ZZ.
RS · Z: Seal (RS) or shield (Z) on one side only, the other side open: for bearings fed oil or grease by the machine.
C3: Internal clearance larger than normal. Standard on electric motors and wherever the shaft runs hot or the fit is tight. Replace a C3 with a C3.
Interchangeable?: Yes. ISO 15 fixes the bore, outside diameter and width, so a 6904 from any maker fits the same shaft and housing. Seals, cage, clearance and quality are what differ.

Other bores in the 69 series

690010 × 22 × 6 mm 690112 × 24 × 6 mm 690215 × 28 × 7 mm 690317 × 30 × 7 mm 690525 × 42 × 9 mm 690630 × 47 × 9 mm 690735 × 55 × 10 mm 690840 × 62 × 12 mm 690945 × 68 × 12 mm 691050 × 72 × 12 mm

Same 20 mm bore, other series

680420 × 32 × 7 mm 600420 × 42 × 12 mm 620420 × 47 × 14 mm 630420 × 52 × 15 mm

Do it with your own numbers

Got a number off a bearing with suffixes on it? Paste it into the bearing number decoder: it reads the whole designation, seals and clearance included.

Keep it on the wall

This answer is one row of the printable bearing size chart — one A4 or Letter page, free, no sign-up.