MISUMI Mech Lab Blog > Mechanical Design > Button Head Socket Cap Size Chart
Button head screw image with technical drawing

Button Head Socket Cap Size Chart

Written by
Scott Bredemann

Published on
May 21, 2026

3 min read

Because button head screw dimensions vary by screw size, thread type, and standard, checking the head diameter, head height, socket size, and thread pitch is important before selecting a fastener. This guide provides button head screw size charts for metric and imperial sizes to help with that.

Inch Button Head Socket Cap Chart

Nominal Screw Size Basic Screw Diameter (d) Head Diameter Max. (A) Head Diameter Min. (A) Head Height Max. (C) Head Height Min. (C) Hex Socket Size (B) Key Engagement Min. (E)
#1 0.0730 in. 0.139 in. 0.129 in. 0.039 in. 0.031 in. 0.050 in. 0.028 in.
#2 0.0860 in. 0.164 in. 0.154 in. 0.046 in. 0.038 in. 0.050 in. 0.028 in.
#3 0.0990 in. 0.188 in. 0.176 in. 0.052 in. 0.044 in. 1/16 in. 0.035 in.
#4 0.1120 in. 0.213 in. 0.201 in. 0.059 in. 0.051 in. 1/16 in. 0.035 in.
#5 0.1250 in. 0.238 in. 0.226 in. 0.066 in. 0.058 in. 5/64 in. 0.044 in.
#6 0.1380 in. 0.262 in. 0.250 in. 0.073 in. 0.063 in. 5/64 in. 0.044 in.
#8 0.1640 in. 0.312 in. 0.298 in. 0.087 in. 0.077 in. 3/32 in. 0.052 in.
#10 0.1900 in. 0.361 in. 0.347 in. 0.101 in. 0.091 in. 1/8 in. 0.070 in.
1/4 0.2500 in. 0.437 in. 0.419 in. 0.132 in. 0.122 in. 5/32 in. 0.087 in.
5/16 0.3125 in. 0.547 in. 0.527 in. 0.166 in. 0.152 in. 3/16 in. 0.094 in.
3/8 0.3750 in. 0.656 in. 0.636 in. 0.199 in. 0.185 in. 7/32 in. 0.122 in.
1/2 0.5000 in. 0.875 in. 0.851 in. 0.265 in. 0.245 in. 5/16 in. 0.175 in.
5/8 0.6250 in. 1.000 in. 0.970 in. 0.331 in. 0.311 in. 3/8 in. 0.210 in.
7/8 0.8750 in. 1.375 in. 1.339 in. 0.464 in. 0.438 in. 1/2 in. 0.280 in.

Note: Dimensions can vary by manufacturer, material, finish, and applicable standard. Confirm exact specifications before final design, machining, or replacement work.

Metric Button Head Socket Cap

Nominal Screw Size Thread Pitch (M×P) Head Diameter Max. (A) Head Diameter Min. (A) Head Height Max. (C) Head Height Min. (C) Hex Socket Size (B) Key Engagement Min. (E)
M2 0.4 mm 3.80 mm 3.50 mm 1.10 mm 0.95 mm 1.3 mm 0.67 mm
M3 0.5 mm 5.70 mm 5.40 mm 1.65 mm 1.43 mm 2.0 mm 1.04 mm
M4 0.7 mm 7.60 mm 7.24 mm 2.20 mm 1.95 mm 2.5 mm 1.30 mm
M5 0.8 mm 9.50 mm 9.14 mm 2.75 mm 2.50 mm 3.0 mm 1.56 mm
M6 1.0 mm 10.50 mm 10.07 mm 3.30 mm 3.00 mm 4.0 mm 2.08 mm
M8 1.25 mm 14.00 mm 13.57 mm 4.40 mm 4.10 mm 5.0 mm 2.60 mm
M10 1.5 mm 17.50 mm 17.07 mm 5.50 mm 5.20 mm 6.0 mm 3.12 mm
M12 1.75 mm 21.00 mm 20.48 mm 6.60 mm 6.24 mm 8.0 mm 4.16 mm
M16 2.0 mm 28.00 mm 27.48 mm 8.80 mm 8.44 mm 10.0 mm 5.20 mm
M20 2.5 mm 35.00 mm 34.40 mm 11.00 mm 10.57 mm 12.0 mm 6.24 mm

⚙ Browse Button Head Cap Screws

Parting Thoughts

MISUMI USA carries a wide range of fasteners, including screws, bolts, nuts, threaded inserts, and more. If you have any questions about fastening concerns for your next project or fix, please feel free to contact our product experts and engineers. For more insights about button head and pan head screws, and other manufacturing-related articles, be sure to check out articles like Industrial Fasteners Selection Guide, Button Head Screw vs. Pan Head Screw, and more.

Disclaimer:
The content on this webpage is for informational purposes only. MISUMI makes no guarantees, expressed or implied, regarding the accuracy, completeness, or validity of the information. Performance parameters, tolerances, designs, materials, or processes should not be assumed to reflect third-party suppliers’ or manufacturers’ deliverables within MISUMI’s network. Buyers are responsible for specifying their part requirements.

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About the Author

Scott Bredemann

Scott is a strategist at MISUMI. He has been writing and editing within the Manufacturing realm for several years. He holds a bachelors, and a masters of science from the University of Illinois. He’s an avid runner, and reader.

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