British Association Fastener Dimensions
The charts below give the dimensions for Hexagon Head, Socket Cap, Socket Countersink, Socket Button screws with British Association (BA) Threads. [cite: 3] Along with dimensions for Full Nuts, Large Flat Washers and Small Flat Washers.
[cite: 3]Dimensions shown are in Inches, if you wish to convert to mm, please use our universal converter.
HEXAGON HEAD DIMENSIONS - BRITISH ASSOCIATION (BA) - BS93:2008
| Nominal Size (D) | Body Diameter (D) | Head Thickness (H) | Across Flats (A/F) | Across Corners (A/C) |
|---|---|---|---|---|
| 10BA | 0.067 | 0.048 | 0.117 | 0.135 |
| 9BA | 0.075 | 0.054 | 0.131 | 0.151 |
| 8BA | 0.087 | 0.063 | 0.152 | 0.176 |
| 7BA | 0.098 | 0.072 | 0.172 | 0.196 |
| 6BA | 0.110 | 0.081 | 0.193 | 0.220 |
| 5BA | 0.126 | 0.092 | 0.220 | 0.251 |
| 4BA | 0.142 | 0.101 | 0.248 | 0.282 |
| 3BA | 0.161 | 0.114 | 0.282 | 0.321 |
| 2BA | 0.185 | 0.130 | 0.324 | 0.369 |
| 1BA | 0.209 | 0.147 | 0.365 | 0.416 |
| 0BA | 0.236 | 0.166 | 0.413 | 0.471 |
SOCKET CAP SCREW DIMENSIONS - BRITISH ASSOCIATION (BA) - BS93:2008
| Nominal Size (D) | Head Height (H) | Head Diameter (A) | Socket A/F (AF) | Socket Depth (O) | Body Diameter (D) |
|---|---|---|---|---|---|
| 10BA | 0.067 | 0.148 | 1/16 | 0.033 | 0.067 |
| 9BA | 0.075 | 0.163 | 1/16 | 0.044 | 0.075 |
| 8BA | 0.110 | 0.157 | 5/64 | 0.055 | 0.087 |
| 7BA | 0.118 | 0.180 | 5/64 | 0.059 | 0.098 |
| 6BA | 0.125 | 0.210 | 3/32 | 0.062 | 0.110 |
| 5BA | 0.134 | 0.230 | 3/32 | 0.064 | 0.126 |
| 4BA | 0.142 | 0.248 | 1/16 | 0.066 | 0.142 |
| 3BA | 0.150 | 0.285 | 1/8 | 0.070 | 0.161 |
| 2BA | 0.161 | 0.324 | 1/8 | 0.075 | 0.185 |
| 1BA | 0.175 | 0.365 | 5/32 | 0.082 | 0.209 |
| 0BA | 0.189 | 0.413 | 5/32 | 0.090 | 0.236 |
FULL NUT DIMENSIONS - BRITISH ASSOCIATION (BA) - BS93:2008
| Nominal Size | Thickness | Across Flats | Across Corners |
|---|---|---|---|
| 0BA | 0.189 | 0.413 | 0.471 |
| 1BA | 0.167 | 0.365 | 0.416 |
| 2BA | 0.148 | 0.324 | 0.369 |
| 3BA | 0.129 | 0.282 | 0.321 |
| 4BA | 0.114 | 0.248 | 0.282 |
| 5BA | 0.101 | 0.220 | 0.251 |
| 6BA | 0.091 | 0.193 | 0.220 |
| 7BA | 0.080 | 0.172 | 0.196 |
| 8BA | 0.071 | 0.152 | 0.176 |
| 9BA | 0.062 | 0.131 | 0.151 |
| 10BA | 0.055 | 0.117 | 0.135 |
LARGE FLAT WASHER DIMENSIONS - BRITISH ASSOCIATION (BA) - BS93:2008
| Nominal Size | Inside Diameter | Outside Diameter | Thickness |
|---|---|---|---|
| 0BA | 0.250 | 0.625 | 0.050 |
| 1BA | 0.221 | 0.560 | 0.045 |
| 2BA | 0.196 | 0.500 | 0.040 |
| 3BA | 0.172 | 0.435 | 0.036 |
| 4BA | 0.152 | 0.375 | 0.030 |
| 5BA | 0.136 | 0.340 | 0.028 |
| 6BA | 0.120 | 0.300 | 0.024 |
| 7BA | 0.108 | 0.270 | 0.024 |
| 8BA | 0.096 | 0.250 | 0.022 |
| 9BA | 0.084 | 0.220 | 0.020 |
| 10BA | 0.076 | 0.200 | 0.020 |
SMALL FLAT WASHER DIMENSIONS - BRITISH ASSOCIATION (BA) - BS93:2008
| Nominal Size | Inside Diameter | Outside Diameter | Thickness |
|---|---|---|---|
| 0BA | 0.242 | 0.500 | 0.040 |
| 1BA | 0.215 | 0.450 | 0.036 |
| 2BA | 0.191 | 0.415 | 0.032 |
| 3BA | 0.166 | 0.365 | 0.030 |
| 4BA | 0.147 | 0.320 | 0.028 |
| 5BA | 0.131 | 0.285 | 0.024 |
| 6BA | 0.116 | 0.250 | 0.022 |
| 7BA | 0.104 | 0.220 | 0.020 |
| 8BA | 0.092 | 0.195 | 0.018 |
| 9BA | 0.080 | 0.170 | 0.016 |
| 10BA | 0.072 | 0.150 | 0.014 |
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