BS4518 SIZE CHART
CHEMICAL COMPATIBILITY CHART
JIS B 2401 SIZE CHART

BS1806 - AS568A O-ring Sizes

1/16" - 1.78MM C/S
3/32" - 2.62MM C/S
Imperial O‑Ring Sizes & Tolerances (BS1806 & AS568A)
1/8" cross section
3.53mm ± 0.10mm 0.139"± 0.004"
Internal diameter Nominal size
Part No. (BS) mm Tol ± Inch Tol ± Shaft Bore
201 4.34 0.13 0.171 0.005 3/16 7/16
202 5.94 0.13 0.234 0.005 1/4 1/2
203 7.52 0.13 0.296 0.005 5/16 9/16
204 9.12 0.13 0.359 0.005 3/8 5/8
205 10.69 0.13 0.421 0.005 7/16 11/16
206 12.29 0.13 0.484 0.005 1/2 3/4
207 13.87 0.13 0.546 0.005 9/16 13/16
208 15.47 0.13 0.609 0.005 5/8 7/8
209 17.04 0.13 0.671 0.005 11/16 15/16
210 18.64 0.15 0.734 0.006 3/4 1
211 20.22 0.15 0.796 0.006 13/16 1.1/16
212 21.82 0.15 0.859 0.006 7/8 1.1/8
213 23.40 0.15 0.921 0.006 15/16 1.3/16
214 24.99 0.15 0.984 0.006 1 1.1/4
618 25.80 0.15 1.016 0.006 1.1/64 -
215 26.58 0.15 1.046 0.006 1.1/16 1.5/16
216 28.17 0.15 1.109 0.006 1.1/8 1.3/8
217 29.75 0.15 1.171 0.006 1.3/16 1.7/16
218 31.34 0.15 1.234 0.006 1.1/4 1.1/2
219 32.92 0.15 1.296 0.006 1.5/16 1.9/16
220 34.52 0.15 1.359 0.006 1.3/8 1.5/8
221 36.10 0.15 1.421 0.006 1.7/16 1.11/16
222 37.69 0.15 1.484 0.006 1.1/2 1.3/4
824 39.69 0.25 1.563 0.010 1.9/16 1.13/16
223 40.87 0.25 1.609 0.010 1.5/8 1.7/8
825 41.28 0.25 1.625 0.010 1.5/8 -
826 42.86 0.25 1.687 0.010 1.11/16 1.15/16
224 44.04 0.25 1.734 0.010 1.3/4 2
827 44.45 0.25 1.750 0.010 - -
828 46.04 0.25 1.812 0.010 1.13/16 2.1/16
225 47.22 0.25 1.859 0.010 1.7/8 2.1/8
829 47.63 0.25 1.875 0.010 - -
830 49.21 0.25 1.937 0.010 1.15/16 2.3/16
226 50.40 0.25 1.984 0.010 2 2.1/4
831 50.80 0.25 2.000 0.010 - -
832 52.39 0.25 2.063 0.010 2.1/16 2.1/8
227 53.57 0.25 2.109 0.010 2.1/8 2.3/8
833 53.98 0.25 2.125 0.010 - -
834 55.56 0.25 2.187 0.010 2.3/16 2.7/16
228 56.74 0.25 2.234 0.010 2.1/4 2.1/2
835 57.12 0.25 2.250 0.010 - -
836 58.74 0.25 2.312 0.010 2.5/16 2.9/16
229 59.92 0.25 2.359 0.010 2.3/8 2.5/8
837 60.33 0.25 2.375 0.010 2.3/8 -
838 61.90 0.25 2.437 0.010 2.7/16 2.11/16
230 63.09 0.25 2.484 0.010 2.1/2 2.3/4
839 63.50 0.25 2.500 0.010 - -
840 65.10 0.25 2.563 0.010 2.9/16 2.13/16
231 66.27 0.25 2.609 0.010 2.5/8 2.7/8
841 66.67 0.38 2.625 0.015 - -
842 68.26 0.38 2.687 0.015 2.11/16 2.15/16
232 69.44 0.38 2.734 0.015 2.3/4 3
843 69.85 0.38 2.750 0.015 2.13/16 -
844 71.44 0.38 2.812 0.015 - -
3/16" - 5.34MM C/S
1/4" - 6.99MM C/S
1/8" cross section
3.53mm ± 0.10mm 0.139"± 0.004"
Internal diameter Nominal size
Part No. (BS) mm Tol ± Inch Tol ± Shaft Bore
233 72.62 0.38 2.859 0.015 2.7/8 3.1/8
845 73.02 0.38 2.875 0.015 - -
846 74.60 0.38 2.937 0.015 2.15/16 3.3/16
234 75.80 0.38 2.984 0.015 3 3.1/4
235 78.97 0.38 3.109 0.015 3.1/8 3.3/8
236 82.14 0.38 3.234 0.015 3.1/4 3.1/2
237 85.32 0.38 3.359 0.015 3.3/8 3.5/8
238 88.50 0.38 3.484 0.015 3.1/2 3.3/4
239 91.67 0.38 3.609 0.015 3.5/8 3.7/8
240 94.84 0.38 3.734 0.015 3.3/4 4
241 98.02 0.38 3.859 0.015 3.7/8 4.1/8
242 101.20 0.38 3.984 0.015 4 4.1/4
243 104.37 0.38 4.109 0.015 4.1/8 4.3/8
244 107.54 0.38 4.234 0.015 4.1/4 4.1/2
245 110.72 0.38 4.359 0.015 4.3/8 4.5/8
246 113.90 0.38 4.484 0.015 4.1/2 4.3/4
247 117.07 0.38 4.609 0.015 4.5/8 4.7/8
248 120.25 0.38 4.734 0.015 4.3/4 5
249 123.42 0.38 4.859 0.015 4.7/8 5.1/8
250 126.60 0.38 4.984 0.015 5 5.1/4
251 129.77 0.58 5.108 0.023 5.1/8 5.3/8
252 132.94 0.58 5.234 0.023 5.1/4 5.1/2
253 136.12 0.58 5.359 0.023 5.3/8 5.5/8
254 139.30 0.58 5.484 0.023 5.1/2 5.3/4
255 142.47 0.58 5.609 0.023 5.5/8 5.7/8
256 145.65 0.58 5.734 0.023 5.3/4 6
257 148.82 0.58 5.859 0.023 5.7/8 6.1/8
258 151.99 0.58 5.984 0.023 6 6.1/4
259 158.35 0.58 6.234 0.023 6.1/4 6.1/2
260 164.70 0.58 6.484 0.023 6.1/2 6.3/4
261 171.05 0.58 6.734 0.023 6.3/4 7
262 177.40 0.58 6.984 0.023 7 7.1/4
263 183.75 0.76 7.234 0.030 7.1/4 7.1/2
264 190.10 0.76 7.484 0.030 7.1/2 7.3/4
265 196.44 0.76 7.734 0.030 7.3/4 8
266 202.79 0.76 7.984 0.030 8 8.1/4
267 209.14 0.76 8.234 0.030 8.1/4 8.1/2
268 215.49 0.76 8.484 0.030 8.1/2 8.3/4
269 221.84 0.76 8.734 0.030 8.3/4 9
270 228.19 0.76 8.984 0.030 9 9.1/4
271 234.54 0.76 9.234 0.030 9.1/4 9.1/2
272 240.89 0.76 9.484 0.030 9.1/2 9.3/4
273 247.24 0.76 9.734 0.030 9.3/4 10
274 253.59 0.76 9.984 0.030 10 10.1/4
275 266.30 0.76 10.484 0.030 10.1/2 10.3/4
276 279.00 0.76 10.984 0.030 11 11.1/4
277 291.70 0.76 11.484 0.030 11.1/2 11.3/4
278 304.39 0.76 11.984 0.030 12 12.1/4
279 329.80 0.76 12.984 0.030 13 13.1/4
280 355.20 0.76 13.984 0.030 14 14.1/4
281 380.60 0.76 14.984 0.030 15 15.1/4
282 405.26 1.14 15.955 0.030 16 16.1/4
283 430.66 1.14 16.955 0.030 17 17.1/4
284 456.06 1.14 17.955 0.030 18 18.1/4