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)
3/16" cross section
5.34mm ± 0.13mm 0.210"± 0.005"
Internal diameter Nominal size
Part No. (BS) mm Tol ± Inch Tol ± Shaft Bore
309 10.46 0.13 0.412 0.005 7/16 13/16
310 12.07 0.13 0.475 0.005 1/2 7/8
311 13.64 0.13 0.537 0.005 9/16 15/16
312 15.24 0.13 0.600 0.005 5/8 1
313 16.81 0.13 0.662 0.005 11/16 1.1/16
314 18.42 0.13 0.725 0.005 3/4 1.1/8
315 19.99 0.15 0.787 0.006 13/16 1.3/16
316 21.59 0.15 0.850 0.006 7/8 1.1/4
317 23.16 0.15 0.912 0.006 15/16 1.5/16
318 24.77 0.15 0.975 0.006 1 1.3/8
319 26.34 0.15 1.037 0.006 1.1/16 1.7/16
320 27.94 0.15 1.100 0.006 1.1/8 1.1/2
321 29.51 0.15 1.162 0.006 1.3/16 1.9/16
322 31.12 0.15 1.225 0.006 1.1/4 1.5/8
323 32.69 0.15 1.287 0.006 1.5/16 1.11/16
324 34.29 0.15 1.350 0.006 1.3/8 1.3/4
325 37.47 0.25 1.475 0.010 1.1/2 1.7/8
326 40.65 0.25 1.600 0.010 1.5/8 2
327 43.82 0.25 1.725 0.010 1.3/4 2.1/8
328 47.00 0.25 1.850 0.010 1.7/8 2.1/4
329 50.16 0.25 1.975 0.010 2 2.3/8
330 53.34 0.25 2.100 0.010 2.1/8 2.1/2
331 56.52 0.25 2.225 0.010 2.1/4 2.5/8
332 59.70 0.25 2.350 0.010 2.3/8 2.3/4
333 62.87 0.25 2.475 0.010 2.1/2 2.7/8
334 66.04 0.25 2.600 0.010 2.5/8 3
335 69.22 0.38 2.725 0.015 2.3/4 3.1/8
336 72.40 0.38 2.850 0.015 2.7/8 3.1/4
619 74.63 0.38 2.938 0.015 2.15/16 3.5/16
337 75.57 0.38 2.975 0.015 3 3.3/8
338 78.74 0.38 3.100 0.015 3.1/8 3.1/2
620 79.77 0.38 3.141 0.015 - -
339 81.92 0.38 3.225 0.015 3.1/4 3.5/8
340 85.09 0.38 3.350 0.015 3.3/8 3.3/4
341 88.27 0.38 3.475 0.015 3.1/2 3.7/8
621 89.69 0.38 3.531 0.015 3.9/16 3.15/16
342 91.44 0.38 3.600 0.015 3.5/8 4
343 94.62 0.38 3.725 0.015 3.3/4 4.1/8
344 97.80 0.38 3.850 0.015 3.7/8 4.1/4
622 100.00 0.38 3.937 0.015 3.15/16 4.5/16
345 100.97 0.38 3.975 0.015 4 4.3/8
346 104.14 0.38 4.100 0.015 4.1/8 4.1/2
347 107.32 0.38 4.225 0.015 4.1/4 4.5/8
623 109.54 0.38 4.312 0.015 - -
348 110.49 0.38 4.350 0.015 4.3/8 4.3/4
349 113.67 0.38 4.475 0.015 4.1/2 4.7/8
350 116.84 0.38 4.600 0.015 4.5/8 5
350A 117.48 0.38 4.625 0.015 - -
351 120.02 0.38 4.725 0.015 4.3/4 5.1/8
351A 120.70 0.38 4.750 0.015 - -
352 123.20 0.38 4.850 0.015 4.7/8 5.1/4
352A 123.80 0.38 4.875 0.015 - -
353 126.37 0.38 4.975 0.015 5 5.3/8
1/8" - 3.53MM C/S
1/4" - 6.99MM C/S
3/16" cross section
5.34mm ± 0.13mm 0.210"± 0.005"
Internal diameter Nominal size
Part No. (BS) mm Tol ± Inch Tol ± Shaft Bore
353A 127.00 0.58 5.000 0.023 - -
354 129.54 0.58 5.100 0.023 5.1/8 5.1/2
354A 130.18 0.58 5.125 0.023 - -
355 132.72 0.58 5.225 0.023 5.1/4 5.5/8
355A 133.35 0.58 5.250 0.023 - -
356 135.90 0.58 5.350 0.023 5.3/8 5.3/4
356A 136.53 0.58 5.375 0.023 - -
357 139.07 0.58 5.475 0.023 5.1/2 5.7/8
357A 139.70 0.58 5.500 0.023 - -
358 142.24 0.58 5.600 0.023 5.5/8 6
358A 142.88 0.58 5.625 0.023 - -
359 145.42 0.58 5.725 0.023 5.3/4 6.1/8
359A 146.05 0.58 5.750 0.023 - -
360 148.60 0.58 5.850 0.023 5.7/8 6.1/4
360A 149.23 0.58 5.875 0.023 - -
361 151.77 0.58 5.975 0.023 6 6.3/8
361A 155.00 0.58 6.100 0.023 6.1/8 6.1/2
362 158.12 0.58 6.225 0.023 6.1/4 6.5/8
362A 161.30 0.58 6.350 0.023 6.3/8 6.3/4
363 164.47 0.58 6.475 0.023 6.1/2 6.5/8
363A 167.70 0.58 6.600 0.023 6.5/8 7
364 170.82 0.58 6.725 0.023 6.3/4 7.1/8
365 177.17 0.58 6.975 0.023 7 7.3/8
366 183.52 0.76 7.225 0.023 7.1/4 7.5/8
367 189.87 0.76 7.425 0.023 7.1/2 7.7/8
368 196.22 0.76 7.725 0.023 7.3/4 8.1/8
369 202.57 0.76 7.975 0.030 8 8.3/8
370 208.92 0.76 8.225 0.030 8.1/4 8.5/8
371 215.27 0.76 8.475 0.030 8.1/2 8.7/8
372 221.62 0.76 8.725 0.030 8.3/4 9.1/8
373 227.97 0.76 8.975 0.030 9 9.3/8
374 234.32 0.76 9.225 0.030 9.1/4 9.5/8
375 240.67 0.76 9.475 0.030 9.1/2 .7/8
376 247.02 0.76 9.725 0.030 9.3/4 10.1/8
377 253.37 0.76 9.975 0.030 10 10.3/8
378 266.07 0.76 10.475 0.030 10.1/2 10.7/8
379 278.77 0.76 10.975 0.030 11 11.3/8
380 291.47 0.76 11.475 0.030 11.1/2 11.7/8
381 304.17 0.76 11.975 0.030 12 12.3/8
382 329.57 0.76 12.975 0.030 13 13.3/8
383 354.97 0.76 13.975 0.030 14 14.3/8
384 380.37 0.76 14.975 0.030 15 15.3/8
385 405.26 1.14 15.975 0.045 16 16.3/8
386 430.66 1.14 16.975 0.045 17 17.3/8
387 456.06 1.14 17.975 0.045 18 18.3/8
388 481.46 1.14 18.975 0.045 19 19.3/8
389 506.81 1.14 19.975 0.045 20 20.3/8
390 532.20 1.14 20.975 0.045 21 21.3/8
391 557.60 1.14 21.955 0.045 22 22.3/8
392 582.68 1.52 22.940 0.060 23 23.3/8
393 608.08 1.52 23.940 0.060 24 24.3/8
394 633.48 1.52 24.940 0.060 25 25.3/8
395 658.88 1.52 25.940 0.060 26 26.3/8