Posted on by Mike M.

300 Series Standard O-Ring Sizes 265-349 (AS 568)

Below is a table of 300 series standard o-ring (0.210″ CS) sizes.  This table actually starts in the 200 series (0.139″ CS) but finishes in the 300-series (0.210″ CS).

If you don’t understand the sizes, check out O-Ring Sizes.  If you don’t know how to use the O-Rings, check out O-Ring Design for Static Sealing.


AS 568A No. Nominal Sizes (inch) Actual Sizes (inch)
ID OD Width ID Width
265 73/4 8 1/8 7.734 ± 0.045 0.139 ± 0.004
266 8 81/4 1/8 7.984 ± 0.045 0.139 ± 0.004
267 81/4 81/2 1/8 8.234 ± 0.050 0.139 ± 0.004
268 81/2 83/4 1/8 8.484 ± 0.050 0.139 ± 0.004
269 83/4 9 1/8 8.734 ± 0.050 0.139 ± 0.004
270 9 91/4 1/8 8.984 ± 0.050 0.139 ± 0.004
271 91/4 91/2 1/8 9.234 ± 0.055 0.139 ± 0.004
272 91/2 93/4 1/8 9.484 ± 0.055 0.139 ± 0.004
273 93/4 10 1/8 9.734 ± 0.055 0.139 ± 0.004
274 10 101/4 1/8 9.984 ± 0.055 0.139 ± 0.004
275 101/2 103/4 1/8 10.484 ± 0.055 0.139 ± 0.004
276 11 111/4 1/8 10.984 ± 0.065 0.139 ± 0.004
277 111/2 113/4 1/8 11.484 ± 0.065 0.139 ± 0.004
278 12 121/4 1/8 11.984 ± 0.065 0.139 ± 0.004
279 13 131/4 1/8 12.984 ± 0.065 0.139 ± 0.004
280 14 141/4 1/8 13.984 ± 0.065 0.139 ± 0.004
281 15 151/4 1/8 14.984 ± 0.065 0.139 ± 0.004
282 16 161/4 1/8 15.955 ± 0.075 0.139 ± 0.004
283 17 171/4 1/8 16.955 ± 0.080 0.139 ± 0.004
284 18 181/4 1/8 17.955 ± 0.085 0.139 ± 0.004
309 7/16 13/16 3/16 0.412 ± 0.005 0.210 ± 0.005
310 1/2 7/8 3/16 0.475 ± 0.005 0.210 ± 0.005
311 9/16 15/16 3/16 0.537 ± 0.007 0.210 ± 0.005
312 3/8 1 3/16 0.600 ± 0.009 0.210 ± 0.005
313 11/16 11/16 3/16 0.662 ± 0.009 0.210 ± 0.005
314 3/4 11/8 3/16 0.725 ± 0.010 0.210 ± 0.005
315 13/16 13/16 3/16 0.787 ± 0.010 0.210 ± 0.005
316 7/8 11/4 3/16 0.850 ± 0.050 0.210 ± 0.005
317 15/16 15/16 3/16 0.912 ± 0.010 0.210 ± 0.005
318 1 13/8 3/16 0.975 ± 0.010 0.210 ± 0.005
319 11/16 17/16 3/16 1.037 ± 0.010 0.210 ± 0.005
320 11/8 11/2 3/16 1.100 ± 0.012 0.210 ± 0.005
321 13/16 19/16 3/16 1.162 ± 0.012 0.210 ± 0.005
322 11/4 15/8 3/16 1.225 ± 0.012 0.210 ± 0.005
323 15/16 111/16 3/16 1.287 ± 0.012 0.210 ± 0.005
324 13/8 13/4 3/16 1.350 ± 0.012 0.210 ± 0.005
325 11/2 17/8 3/16 1.475 ± 0.015 0.210 ± 0.005
326 15/8 2 3/16 1.600 ± 0.015 0.210 ± 0.005
327 13/4 21/8 3/16 1.725 ± 0.015 0.210 ± 0.005
328 17/8 21/4 3/16 1.850 ± 0.015 0.210 ± 0.005
329 2 23/8 3/16 1.975 ± 0.018 0.210 ± 0.005
330 21/8 21/2 3/16 2.100 ± 0.018 0.210 ± 0.005
331 21/4 25/8 3/16 2.225 ± 0.018 0.210 ± 0.005
332 23/8 23/4 3/16 2.350 ± 0.018 0.210 ± 0.005
333 21/2 27/8 3/16 2.475 ± 0.020 0.210 ± 0.005
334 25/8 3 3/16 2.600 ± 0.020 0.210 ± 0.005
335 23/4 31/8 3/16 2.725 ± 0.020 0.210 ± 0.005
336 27/8 31/4 3/16 2.850 ± 0.020 0.210 ± 0.005
337 3 33/8 3/16 2.975 ± 0.024 0.210 ± 0.005
338 31/8 31/2 3/16 3.100 ± 0.024 0.210 ± 0.005
339 31/4 35/8 3/16 3.225 ± 0.024 0.210 ± 0.005
340 33/8 33/4 3/16 3.350 ± 0.024 0.210 ± 0.005
341 31/2 37/8 3/16 3.475 ± 0.024 0.210 ± 0.005
342 35/8 4 3/16 3.600 ± 0.028 0.210 ± 0.005
343 33/4 41/8 3/16 3.725 ± 0.028 0.210 ± 0.005
344 37/8 41/4 3/16 3.850 ± 0.028 0.210 ± 0.005
345 4 43/8 3/16 3.975 ± 0.028 0.210 ± 0.005
346 41/8 41/2 3/16 4.100 ± 0.028 0.210 ± 0.005
347 41/4 45/8 3/16 4.225 ± 0.030 0.210 ± 0.005
348 43/8 43/4 3/16 4.350 ± 0.030 0.210 ± 0.005
349 41/2 47/8 3/16 4.475 ± 0.030 0.210 ± 0.005

Other Sizes:

000 Series Standard O-Ring Table (001-114)
100 Series Standard O-Ring Table (115-178)
200 Series Standard O-Ring Table (201-264)
300 Series Standard O-Ring Table (265-349)
400 Series Standard O-Ring Table (350-439)