BS 4518 Metric O-Ring Size Chart

BS 4518 is the British Standard for metric O-rings, where the size code reads as inside diameter in 0.1 mm followed by cross-section in 0.1 mm. Use this chart to match a code to its exact ID and section, then ARC molds them to spec in your required compound.

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Sourcing BS 4518 metric O-rings for your build

The BS 4518 metric O-ring size chart is the fast way to translate a British Standard size code into a real seal. Read the code as inside diameter in 0.1 mm followed by cross-section in 0.1 mm, and the chart gives you the exact ID and section you need. Engineers and buyers use it to look up BS 4518 O-ring sizes, confirm a part against a gland or groove, and pin down the metric dimensions before they source or requote a seal.

Once you have the code, ARC molds it to spec. As a US custom rubber components manufacturer, we build BS 4518 O-rings in the compound your application demands — NBR, FKM, EPDM, silicone, HNBR and more — with certified materials backed by our ISO 9001:2015 and IATF 16949:2016 quality systems. Send the size code, ID and cross-section and our engineers confirm the material, tooling and a fast path to a quote.

BS 4518 Metric O-Rings

Issued by the British Standards Institution, Standard BS 4518 identifies British Standard metric sizes. The size code for these O-Rings is a four digit number indicating the O-Ring I.D. in tenths of millimeters followed by a hyphen and two digits indicating the O-Ring Cross Section, also in tenths of a millimeter.

For a complete listing of all metric o-ring sizes, visit our
Metric O-Ring Cross Reference Table.

BS 4518 Size Chart

Global Part#	Reference	C/S (MM)	I.D. (MM)	C/S (Inch)	I.D. (Inch)
1.60X003.1	0031-16	1.6	3.1	0.063	0.122
1.60X004.1	0041-16	1.6	4.1	0.063	0.161
1.60X005.1	0051-16	1.6	5.1	0.063	0.201
1.60X006.1	0061-16	1.6	6.1	0.063	0.24
1.60X007.1	0071-16	1.6	7.1	0.063	0.28
1.60X008.1	0081-16	1.6	8.1	0.063	0.319
1.60X009.1	0091-16	1.6	9.1	0.063	0.358
1.60X010.1	0101-16	1.6	10.1	0.063	0.398
1.60X011.1	0111-16	1.6	11.1	0.063	0.437
1.60X012.1	0121-16	1.6	12.1	0.063	0.476
1.60X013.1	0131-16	1.6	13.1	0.063	0.516
1.60X014.1	0141-16	1.6	14.1	0.063	0.555
1.60X015.1	0151-16	1.6	15.1	0.063	0.594
1.60X016.1	0161-16	1.6	16.1	0.063	0.634
1.60X017.1	0171-16	1.6	17.1	0.063	0.673
1.60X018.1	0181-16	1.6	18.1	0.063	0.713
1.60X019.1	0191-16	1.6	19.1	0.063	0.752
1.60X020.1	0201-16	1.6	20.1	0.063	0.791
1.60X021.1	0211-16	1.6	21.1	0.063	0.831
1.60X022.1	0221-16	1.6	22.1	0.063	0.87
1.60X025.1	0251-16	1.6	25.1	0.063	0.988
1.60X027.1	0271-16	1.6	27.1	0.063	1.067
1.60X029.1	0291-16	1.6	29.1	0.063	1.146
1.60X032.1	0321-16	1.6	32.1	0.063	1.264
1.60X035.1	0351-16	1.6	35.1	0.063	1.382
1.60X037.1	0371-16	1.6	37.1	0.063	1.461
2.40X003.6	0036-24	2.4	3.6	0.094	0.142
2.40X004.6	0046-24	2.4	4.6	0.094	0.181
2.40X005.6	0056-24	2.4	5.6	0.094	0.22
2.40X006.6	0066-24	2.4	6.6	0.094	0.26
2.40X007.6	0076-24	2.4	7.6	0.094	0.299
2.40X008.6	0086-24	2.4	8.6	0.094	0.339
2.40X009.6	0096-24	2.4	9.6	0.094	0.378
2.40X010.6	0106-24	2.4	10.6	0.094	0.417
2.40X011.6	0116-24	2.4	11.6	0.094	0.457
2.40X012.6	0126-24	2.4	12.6	0.094	0.496
2.40X013.6	0136-24	2.4	13.6	0.094	0.535
2.40X014.6	0146-24	2.4	14.6	0.094	0.575
2.40X015.6	0156-24	2.4	15.6	0.094	0.614
2.40X016.6	0166-24	2.4	16.6	0.094	0.654
2.40X017.6	0176-24	2.4	17.6	0.094	0.693
2.40X018.6	0186-24	2.4	18.6	0.094	0.732
2.40X019.6	0196-24	2.4	19.6	0.094	0.772
2.40X020.6	0206-24	2.4	20.6	0.094	0.811
2.40X021.6	0216-24	2.4	21.6	0.094	0.85
2.40X024.6	0246-24	2.4	24.6	0.094	0.969
2.40X027.6	0276-24	2.4	27.6	0.094	1.087
2.40X029.6	0296-24	2.4	29.6	0.094	1.165
2.40X031.6	0316-24	2.4	31.6	0.094	1.244
2.40X034.6	0346-24	2.4	34.6	0.094	1.362
2.40X035.6	0356-24	2.4	35.6	0.094	1.402
2.40X037.6	0376-24	2.4	37.6	0.094	1.48
2.40X039.6	0396-24	2.4	39.6	0.094	1.559
2.40X041.6	0416-24	2.4	41.6	0.094	1.638
2.40X044.6	0446-24	2.4	44.6	0.094	1.756
2.40X045.6	0456-24	2.4	45.6	0.094	1.795
2.40X047.6	0476-24	2.4	47.6	0.094	1.874
2.40X049.6	0496-24	2.4	49.6	0.094	1.953
2.40X051.6	0516-24	2.4	51.6	0.094	2.031
2.40X054.6	0546-24	2.4	54.6	0.094	2.15
2.40X055.6	0556-24	2.4	55.6	0.094	2.189
2.40X057.6	0576-24	2.4	57.6	0.094	2.268
2.40X058.6	0586-24	2.4	58.6	0.094	2.307
2.40X059.6	0596-24	2.4	59.6	0.094	2.346
2.40X061.6	0616-24	2.4	61.6	0.094	2.425
2.40X062.6	0626-24	2.4	62.6	0.094	2.465
2.40X064.6	0646-24	2.4	64.6	0.094	2.543
2.40X067.6	0676-24	2.4	67.6	0.094	2.661
2.40X069.6	0696-24	2.4	69.6	0.094	2.74
3.00X019.5	0195-30	3	19.5	0.118	0.768
3.00X021.5	0215-30	3	21.5	0.118	0.846
3.00X022.5	0225-30	3	22.5	0.118	0.886
3.00X024.5	0245-30	3	24.5	0.118	0.965
3.00X025.5	0255-30	3	25.5	0.118	1.004
3.00X026.5	0265-30	3	26.5	0.118	1.043
3.00X027.5	0275-30	3	27.5	0.118	1.083
3.00X029.5	0295-30	3	29.5	0.118	1.161
3.00X031.5	0315-30	3	31.5	0.118	1.24
3.00X032.5	0325-30	3	32.5	0.118	1.28
3.00X034.5	0345-30	3	34.5	0.118	1.358
3.00X035.5	0355-30	3	35.5	0.118	1.398
3.00X036.5	0365-30	3	36.5	0.118	1.437
3.00X037.5	0375-30	3	37.5	0.118	1.476
3.00X039.5	0395-30	3	39.5	0.118	1.555
3.00X041.5	0415-30	3	41.5	0.118	1.634
3.00X042.5	0425-30	3	42.5	0.118	1.673
3.00X044.5	0445-30	3	44.5	0.118	1.752
3.00X049.5	0495-30	3	49.5	0.118	1.949
3.00X054.5	0545-30	3	54.5	0.118	2.146
3.00X055.5	0555-30	3	55.5	0.118	2.185
3.00X057.5	0575-30	3	57.5	0.118	2.264
3.00X059.5	0595-30	3	59.5	0.118	2.343
3.00X062.5	0625-30	3	62.5	0.118	2.461
3.00X064.5	0645-30	3	64.5	0.118	2.539
3.00X069.5	0695-30	3	69.5	0.118	2.736
3.00X074.5	0745-30	3	74.5	0.118	2.933
3.00X079.5	0795-30	3	79.5	0.118	3.13
3.00X084.5	0845-30	3	84.5	0.118	3.327
3.00X089.5	0895-30	3	89.5	0.118	3.524
3.00X094.5	0945-30	3	94.5	0.118	3.72
3.00X099.5	0995-30	3	99.5	0.118	3.917
3.00X104.5	1045-30	3	104.5	0.118	4.114
3.00X109.5	1095-30	3	109.5	0.118	4.311
3.00X114.5	1145-30	3	114.5	0.118	4.508
3.00X119.5	1195-30	3	119.5	0.118	4.705
3.00X124.5	1245-30	3	124.5	0.118	4.902
3.00X129.5	1295-30	3	129.5	0.118	5.098
3.00X134.5	1345-30	3	134.5	0.118	5.295
3.00X139.5	1395-30	3	139.5	0.118	5.492
3.00X144.5	1445-30	3	144.5	0.118	5.689
3.00X149.5	1495-30	3	149.5	0.118	5.886
3.00X154.5	1545-30	3	154.5	0.118	6.083
3.00X159.5	1595-30	3	159.5	0.118	6.28
3.00X164.5	1645-30	3	164.5	0.118	6.476
3.00X169.5	1695-30	3	169.5	0.118	6.673
3.00X174.5	1745-30	3	174.5	0.118	6.87
3.00X179.5	1795-30	3	179.5	0.118	7.067
3.00X184.5	1845-30	3	184.5	0.118	7.264
3.00X189.5	1895-30	3	189.5	0.118	7.461
3.00X194.5	1945-30	3	194.5	0.118	7.657
3.00X199.5	1995-30	3	199.5	0.118	7.854
3.00X209.5	2095-30	3	209.5	0.118	8.248
3.00X219.5	2195-30	3	219.5	0.118	8.642
3.00X229.5	2295-30	3	229.5	0.118	9.035
3.00X239.5	2395-30	3	239.5	0.118	9.429
3.00X244.5	2445-30	3	244.5	0.118	9.626
3.00X249.5	2495-30	3	249.5	0.118	9.823
5.70X044.3	0443-57	5.7	44.3	0.224	1.744
5.70X045.3	0453-57	5.7	45.3	0.224	1.783
5.70X049.3	0493-57	5.7	49.3	0.224	1.941
5.70X052.3	0523-57	5.7	52.3	0.224	2.059
5.70X054.3	0543-57	5.7	54.3	0.224	2.138
5.70X055.3	0553-57	5.7	55.3	0.224	2.177
5.70X059.3	0593-57	5.7	59.3	0.224	2.335
5.70X062.3	0623-57	5.7	62.3	0.224	2.453
5.70X064.3	0643-57	5.7	64.3	0.224	2.531
5.70X069.3	0693-57	5.7	69.3	0.224	2.728
5.70X074.3	0743-57	5.7	74.3	0.224	2.925
5.70X079.3	0793-57	5.7	79.3	0.224	3.122
5.70X084.3	0843-57	5.7	84.3	0.224	3.319
5.70X089.3	0893-57	5.7	89.3	0.224	3.516
5.70X094.3	0943-57	5.7	94.3	0.224	3.713
5.70X099.3	0993-57	5.7	99.3	0.224	3.909
5.70X104.3	1043-57	5.7	104.3	0.224	4.106
5.70X109.3	1093-57	5.7	109.3	0.224	4.303
5.70X114.3	1143-57	5.7	114.3	0.224	4.5
5.70X119.3	1193-57	5.7	119.3	0.224	4.697
5.70X124.3	1243-57	5.7	124.3	0.224	4.894
5.70X129.3	1293-57	5.7	129.3	0.224	5.091
5.70X134.3	1343-57	5.7	134.3	0.224	5.287
5.70X139.3	1393-57	5.7	139.3	0.224	5.484
5.70X144.3	1443-57	5.7	144.3	0.224	5.681
5.70X149.3	1493-57	5.7	149.3	0.224	5.878
5.70X154.3	1543-57	5.7	154.3	0.224	6.075
5.70X159.3	1593-57	5.7	159.3	0.224	6.272
5.70X164.3	1643-57	5.7	164.3	0.224	6.469
5.70X169.3	1693-57	5.7	169.3	0.224	6.665
5.70X174.3	1743-57	5.7	174.3	0.224	6.862
5.70X179.3	1793-57	5.7	179.3	0.224	7.059
5.70X184.3	1843-57	5.7	184.3	0.224	7.256
5.70X189.3	1893-57	5.7	189.3	0.224	7.453
5.70X194.3	1943-57	5.7	194.3	0.224	7.65
5.70X199.3	1993-57	5.7	199.3	0.224	7.846
5.70X209.3	2093-57	5.7	209.3	0.224	8.24
5.70X219.3	2193-57	5.7	219.3	0.224	8.634
5.70X229.3	2293-57	5.7	229.3	0.224	9.028
5.70X239.3	2393-57	5.7	239.3	0.224	9.421
5.70X249.3	2493-57	5.7	249.3	0.224	9.815
5.70X259.3	2593-57	5.7	259.3	0.224	10.209
5.70X269.3	2693-57	5.7	269.3	0.224	10.602
5.70X279.3	2793-57	5.7	279.3	0.224	10.996
5.70X289.3	2893-57	5.7	289.3	0.224	11.39
5.70X299.3	2993-57	5.7	299.3	0.224	11.783
5.70X309.3	3093-57	5.7	309.3	0.224	12.177
5.70X319.3	3193-57	5.7	319.3	0.224	12.571
5.70X339.3	3393-57	5.7	339.3	0.224	13.358
5.70X359.3	3593-57	5.7	359.3	0.224	14.146
5.70X379.3	3793-57	5.7	379.3	0.224	14.933
5.70X389.3	3893-57	5.7	389.3	0.224	15.327
5.70X399.3	3993-57	5.7	399.3	0.224	15.72
5.70X419.3	4193-57	5.7	419.3	0.224	16.508
5.70X439.3	4393-57	5.7	439.3	0.224	17.295
5.70X459.3	4593-57	5.7	459.3	0.224	18.083
5.70X479.3	4793-57	5.7	479.3	0.224	18.87
5.70X489.3	4893-57	5.7	489.3	0.224	19.264
5.70X499.3	4993-57	5.7	499.3	0.224	19.657
8.40X144.1	1441-84	8.4	144.1	0.331	5.673
8.40X149.1	1491-84	8.4	149.1	0.331	5.87
8.40X154.1	1541-84	8.4	154.1	0.331	6.067
8.40X159.1	1591-84	8.4	159.1	0.331	6.264
8.40X164.1	1641-84	8.4	164.1	0.331	6.461
8.40X169.1	1691-84	8.4	169.1	0.331	6.657
8.40X174.1	1741-84	8.4	174.1	0.331	6.854
8.40X179.1	1791-84	8.4	179.1	0.331	7.051
8.40X184.1	1841-84	8.4	184.1	0.331	7.248
8.40X189.1	1891-84	8.4	189.1	0.331	7.445
8.40X194.1	1941-84	8.4	194.1	0.331	7.642
8.40X199.1	1991-84	8.4	199.1	0.331	7.839
8.40X204.1	2041-84	8.4	204.1	0.331	8.035
8.40X209.1	2091-84	8.4	209.1	0.331	8.232
8.40X219.1	2191-84	8.4	219.1	0.331	8.626
8.40X229.1	2291-84	8.4	229.1	0.331	9.02
8.40X234.1	2341-84	8.4	234.1	0.331	9.217
8.40X239.1	2391-84	8.4	239.1	0.331	9.413
8.40X249.1	2491-84	8.4	249.1	0.331	9.807
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BS 4518 Metric O-Ring Size Chart

Sourcing BS 4518 metric O-rings for your build

BS 4518 Metric O-Rings

BS 4518 Size Chart

Need BS 4518 O-rings built to spec?

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