BS4518 SIZE CHART
CHEMICAL COMPATIBILITY CHART
JIS B 2401 SIZE CHART

BS1806 - AS568A O-ring Sizes

1/16" - 1.78MM C/S
1/8" - 3.53MM C/S
Imperial O‑Ring Sizes & Tolerances (BS1806 & AS568A)
3/32" cross section
2.62mm ± 0.08mm 0.103"± 0.003"
Internal diameter Nominal size
Part No. (BS) mm Tol ± Inch Tol ± Shaft Bore
102 1.24 0.10 0.049 0.004 1/16 1/4
103 2.06 0.13 0.081 0.005 3/32 9/32
104 2.84 0.13 0.112 0.005 1/8 5/16
105 3.63 0.13 0.143 0.005 5/32 11/32
106 4.42 0.13 0.174 0.005 3/16 3/8
107 5.23 0.13 0.206 0.005 7/32 13/32
108 6.02 0.13 0.237 0.005 1/4 7/16
109 7.60 0.13 0.299 0.005 5/16 1/2
110 9.19 0.13 0.362 0.005 3/8 9/16
613 9.92 0.13 0.391 0.005 25/64 37/64
111 10.78 0.13 0.424 0.005 7/16 5/8
614 11.91 0.13 0.469 0.005 15/32 21/32
112 12.37 0.13 0.487 0.005 1/2 11/16
615 13.10 0.13 0.516 0.005 33/64 45/64
113 13.95 0.13 0.549 0.005 9/16 3/4
616 15.08 0.13 0.594 0.005 19/32 25/32
114 15.54 0.13 0.612 0.005 5/8 13/16
809 15.88 0.13 0.625 0.005 - -
115 17.13 0.13 0.674 0.005 11/16 7/8
617 17.86 0.13 0.703 0.005 - -
116 18.72 0.13 0.737 0.005 3/4 15/16
117 20.29 0.15 0.799 0.006 13/16 1
812 20.63 0.15 0.812 0.006 - -
118 21.89 0.15 0.862 0.006 7/8 1.1/16
813 22.22 0.15 0.875 0.006 - -
119 23.47 0.15 0.925 0.006 15/16 1.1/8
814 23.81 0.15 0.937 0.006 - -
120 25.07 0.15 0.987 0.006 1 1.3/16
121 26.64 0.15 1.049 0.006 1.1/16 1.1/4
122 28.25 0.15 1.112 0.006 1.1/8 1.5/16
123 29.82 0.15 1.174 0.006 1.3/16 1.3/8
124 31.42 0.15 1.237 0.006 1.1/4 1.7/16
125 33.00 0.15 1.299 0.006 1.5/16 1.1/2
126 34.59 0.15 1.362 0.006 1.3/8 1.9/16
127 36.17 0.15 1.424 0.006 1.7/16 1.5/8
128 37.77 0.15 1.487 0.006 1.1/2 1.11/16
129 39.34 0.25 1.549 0.010 1.9/16 1.3/4
130 40.95 0.25 1.612 0.010 1.5/8 1.13/16
131 42.52 0.25 1.674 0.010 1.11/16 1.7/8
132 44.12 0.25 1.737 0.010 1.3/4 1.15/16
133 45.69 0.25 1.799 0.010 1.13/16 2
134 47.29 0.25 1.862 0.010 1.7/8 2.1/16
135 48.90 0.25 1.925 0.010 1.15/16 2.1/8
136 50.47 0.25 1.987 0.010 2 2.3/16
137 52.07 0.25 2.050 0.010 2.1/16 2.1/4
3/16" - 5.34MM C/S
1/4" - 6.99MM C/S
3/32" cross section
2.62mm ± 0.08mm 0.103"± 0.003"
Internal diameter Nominal size
Part No. (BS) mm Tol ± Inch Tol ± Shaft Bore
138 53.65 0.25 2.112 0.010 2.1/16 2.5/16
139 55.25 0.25 2.175 0.010 2.3/16 2.3/8
140 56.82 0.25 2.237 0.010 2.1/4 2.7/16
141 58.42 0.25 2.300 0.010 2.5/16 2.1/2
142 60.00 0.25 2.362 0.010 2.3/8 2.9/16
143 61.60 0.25 2.425 0.010 2.7/16 2.5/8
144 63.17 0.25 2.487 0.010 2.1/2 2.11/16
145 64.77 0.25 2.550 0.010 2.9/16 2.3/4
146 66.35 0.25 2.612 0.010 2.5/8 2.13/16
147 67.95 0.38 2.675 0.015 2.11/16 2.7/8
148 69.52 0.38 2.737 0.015 2.3/4 2.15/16
149 71.12 0.38 2.800 0.015 2.13/16 3
150 72.69 0.38 2.862 0.015 2.7/8 3.1/16
640 74.30 0.38 2.924 0.015 2.15/16 3.1/8
151 75.87 0.38 2.987 0.015 3 3.3/16
641 77.50 0.38 3.049 0.015 3.1/16 3.1/4
642 80.60 0.38 3.174 0.015 3.3/16 3.3/8
152 82.22 0.38 3.237 0.015 3.1/4 3.7/16
643 83.80 0.38 3.299 0.015 3.5/16 3.1/2
153 88.57 0.38 3.487 0.015 3.1/2 3.11/16
154 94.93 0.38 3.737 0.015 3.3/4 3.15/16
155 101.27 0.38 3.987 0.015 4 4.3/16
156 107.63 0.38 4.237 0.015 4.1/4 4.7/16
157 113.98 0.38 4.487 0.015 4.1/2 4.11/16
158 120.33 0.38 4.737 0.015 4.3/4 4.15/16
159 126.67 0.38 4.987 0.015 5 5.3/16
160 133.00 0.58 5.237 0.023 5.1/4 5.7/16
161 139.38 0.58 5.487 0.023 5.1/2 5.11/16
162 145.72 0.58 5.737 0.023 5.3/4 5.15/16
163 152.07 0.58 5.987 0.023 6 6.3/16
164 158.41 0.58 6.237 0.023 6.1/4 6.7/16
165 164.78 0.58 6.487 0.023 6.1/2 6.11/16
166 171.13 0.58 6.737 0.023 6.3/4 6.15/16
167 177.47 0.58 6.987 0.023 7 7.3/16
168 183.83 0.76 7.237 0.030 7.1/4 7.7/16
169 190.18 0.76 7.487 0.030 7.1/2 7.11/16
170 196.58 0.76 7.737 0.030 7.3/4 7.15/16
171 202.87 0.76 7.987 0.030 8 8.3/16
172 209.23 0.76 8.237 0.030 8.1/4 8.7/16
173 215.58 0.76 8.487 0.030 8.1/2 8.11/16
174 221.93 0.76 8.737 0.030 8.3/4 8.15/16
175 228.28 0.76 8.987 0.030 9 9.3/16
176 234.63 0.76 9.237 0.030 9.1/4 9.7/16
177 240.98 0.76 9.487 0.030 9.1/2 9.11/16
178 247.33 0.76 9.737 0.030 9.3/4 9.15/16