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DIN 472 Internal Circlip Size Chart (Bore Retaining Rings)

Guide · Updated October 28, 2026

An internal circlip, or bore retaining ring, is a spring steel ring that snaps into a groove inside a bore to hold a bearing, bush or seal in a housing. DIN 472 is the metric standard for these rings and the grooves you cut for them. The chart below covers the common 8 to 100 mm sizes. Ring thickness, free diameter, groove diameter, groove width, groove depth and edge distance agree between the RoyMech DIN 472 table, the Kenatec DIN 472 table and the Ekinsun DIN 472 groove table. DIN 472 was revised in May 2026, so check the current edition or your ring supplier for critical work.

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Step by step

Measure the bore: Check the bore where the ring will sit with a bore gage. The DIN 472 size is the bore diameter d1.
Read the groove: Find d1 in the chart and read the groove diameter d2, the groove width m and the ring thickness s. On a bore ring d2 is bigger than d1.
Check edge distance: Keep at least n of housing between the groove and the bore mouth or any step, or the groove wall can shear out.
Cut the groove: Use a boring bar grooving tool ground to m or a little under. Feed out to d2 and hold it to its plus tolerance.
Keep the wall square: Leave the loaded groove wall square and the corner sharp. A rounded edge lets the ring roll out under load.
Fit the ring: Close it with internal circlip pliers only as far as needed to pass into the bore, then check it springs fully into the groove all round.

DIN 472 ring and groove dimensions (mm)

Columns are: nominal bore diameter d1, ring thickness s, ring free diameter d3, groove diameter d2, minimum groove width m, groove depth t = (d2 − d1) / 2, and minimum distance n from the groove to the bore mouth. Groove width m is held to H13, so it can be up to 0.14 mm over the listed figure up to 2.65 mm wide and 0.18 mm over at 3.15 mm. Groove diameter d2 is a plus tolerance, cut into the housing: +0.09 mm for 8 to 9 mm bores, +0.11 for 10 to 17, +0.13 for 18 to 22, +0.21 for 24 to 28, +0.25 for 30 to 47, +0.30 for 50 to 75 and +0.35 for 80 to 100 mm.

Bore d1 | Ring thickness s | Free dia d3 | Groove dia d2 | Groove width m (min) | Groove depth t | Min edge distance n
8 | 0.8 | 8.70 | 8.4 | 0.9 | 0.2 | 0.6
9 | 0.8 | 9.80 | 9.4 | 0.9 | 0.2 | 0.6
10 | 1 | 10.80 | 10.4 | 1.1 | 0.2 | 0.6
11 | 1 | 11.80 | 11.4 | 1.1 | 0.2 | 0.6
12 | 1 | 13.00 | 12.5 | 1.1 | 0.25 | 0.8
13 | 1 | 14.10 | 13.6 | 1.1 | 0.3 | 0.9
14 | 1 | 15.10 | 14.6 | 1.1 | 0.3 | 0.9
15 | 1 | 16.20 | 15.7 | 1.1 | 0.35 | 1.1
16 | 1 | 17.30 | 16.8 | 1.1 | 0.4 | 1.2
17 | 1 | 18.30 | 17.8 | 1.1 | 0.4 | 1.2
18 | 1 | 19.50 | 19 | 1.1 | 0.5 | 1.5
19 | 1 | 20.50 | 20 | 1.1 | 0.5 | 1.5
20 | 1 | 21.50 | 21 | 1.1 | 0.5 | 1.5
21 | 1 | 22.50 | 22 | 1.1 | 0.5 | 1.5
22 | 1 | 23.50 | 23 | 1.1 | 0.5 | 1.5
24 | 1.2 | 25.90 | 25.2 | 1.3 | 0.6 | 1.8
25 | 1.2 | 26.90 | 26.2 | 1.3 | 0.6 | 1.8
26 | 1.2 | 27.90 | 27.2 | 1.3 | 0.6 | 1.8
28 | 1.2 | 30.10 | 29.4 | 1.3 | 0.7 | 2.1
30 | 1.2 | 32.10 | 31.4 | 1.3 | 0.7 | 2.1
32 | 1.2 | 34.40 | 33.7 | 1.3 | 0.85 | 2.6
34 | 1.5 | 36.50 | 35.7 | 1.6 | 0.85 | 2.6
35 | 1.5 | 37.80 | 37 | 1.6 | 1 | 3
37 | 1.5 | 39.80 | 39 | 1.6 | 1 | 3
40 | 1.75 | 43.50 | 42.5 | 1.85 | 1.25 | 3.8
42 | 1.75 | 45.50 | 44.5 | 1.85 | 1.25 | 3.8
45 | 1.75 | 48.50 | 47.5 | 1.85 | 1.25 | 3.8
47 | 1.75 | 50.50 | 49.5 | 1.85 | 1.25 | 3.8
50 | 2 | 54.20 | 53 | 2.15 | 1.5 | 4.5
52 | 2 | 56.20 | 55 | 2.15 | 1.5 | 4.5
55 | 2 | 59.20 | 58 | 2.15 | 1.5 | 4.5
62 | 2 | 66.20 | 65 | 2.15 | 1.5 | 4.5
68 | 2.5 | 72.50 | 71 | 2.65 | 1.5 | 4.5
72 | 2.5 | 76.5 | 75 | 2.65 | 1.5 | 4.5
75 | 2.5 | 79.50 | 78 | 2.65 | 1.5 | 4.5
80 | 2.5 | 85.50 | 83.5 | 2.65 | 1.75 | 5.3
85 | 3 | 90.50 | 88.5 | 3.15 | 1.75 | 5.3
90 | 3 | 95.50 | 93.5 | 3.15 | 1.75 | 5.3
100 | 3 | 105.50 | 103.5 | 3.15 | 1.75 | 5.3

How to read the chart

Ring thickness steps up in bands: 0.8 mm to a 9 mm bore, 1.0 mm to 22, 1.2 mm to 32, 1.5 mm to 38, 1.75 mm to 48, 2.0 mm to 63, 2.5 mm to 82 and 3.0 mm to 100. Groove width is that thickness plus 0.1 to 0.15 mm. Groove depth grows from 0.2 mm on small bores to 1.75 mm at 80 mm and up. The ring's free diameter d3 is always a little bigger than the groove, so it stays tight against the groove bottom.

One row to watch: some tables list the 48 mm ring as 2.0 mm thick. Kenatec and Ekinsun both give 1.75 mm with a 1.85 mm groove, and the groove width in every table matches a 1.75 mm ring, so that is what we list. Check the ring you buy before you cut.

Sizes not in the list, such as 23, 27, 36 or 58 mm, exist in DIN 472 too but are less common. Buy the ring first and check the supplier's groove figure for odd sizes.

Worked example: housing for a 6204 bearing

A 6204 bearing has a 47 mm outside diameter and 14 mm width. The chart gives s = 1.75 mm, d2 = 49.5 mm, m = 1.85 mm and n = 3.8 mm. Groove depth is (49.5 − 47) / 2 = 1.25 mm a side. Bore the groove to 49.50 to 49.75 mm (+0.25 mm tolerance) and 1.85 to about 1.99 mm wide. Put the near wall 14.0 mm from the bore shoulder, plus a few hundredths for end float, and leave at least 3.8 mm of housing past the groove.

Worked example: cutting a 35 mm bore groove

For 35 mm, s = 1.5, m = 1.6 and d2 = 37.0 mm, so you feed out 1.0 mm on the radius. On a manual lathe, touch the grooving tool on the bore wall, zero the cross slide and feed 1.0 mm (2.0 mm on a diameter dial). With a 1.5 mm insert, plunge, step 0.1 mm along and plunge again to open the width to 1.6 mm.

Worked example: checking a used housing

A 62 mm housing groove measures 65.2 mm with a 2.2 mm width. DIN 472 wants 65.0 to 65.3 mm, so the diameter is fine. Width is over the 2.15 mm minimum and inside H13 (up to 2.29 mm), so a standard 2.0 mm ring fits. If the ring rattles in the groove, check the groove wall for wear before you blame the ring.

Internal vs external rings

DIN 472 rings go in bores and spring out into the groove. DIN 471 rings go on shafts and close in. Internal pliers close the ring to fit it; external pliers open it. See the DIN 471 external circlip chart for shaft rings.

Common problems

Ring will not go in: the bore entry has a burr or sharp edge. Add a small lead-in chamfer at the bore mouth.
Ring pops out under load: edge distance n is too small, or the groove corner is rounded. Recut with a square wall.
Ring loose in the groove: the groove is oversize or the ring was over closed. Use a new ring and check d2.
Bearing has end play: the groove is too far from the shoulder. Add a shim or wave washer.

FAQ

What size circlip fits a 47 mm bore?

A DIN 472 47 mm ring, which suits a 6204 bearing housing. It is 1.75 mm thick and needs a 49.5 mm groove at least 1.85 mm wide, with 3.8 mm from the groove to the bore mouth.

How deep is a DIN 472 groove?

Depth t is half of groove minus bore diameter. For a 35 mm bore, (37.0 − 35) / 2 = 1.0 mm a side.

What is the free diameter d3?

It is the ring's outside diameter before fitting. It is larger than the groove, so the ring presses out against the groove bottom once fitted.

Can I use a DIN 471 ring in a bore?

No. DIN 471 rings are for shafts and close in. A bore needs a DIN 472 ring, which springs out, and internal pliers to fit it.

Pin and retaining-ring size charts

Picking a fastener to locate or retain a part? Compare the other pin and ring charts in this set:

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