Dimensions For Standard Hex Cap Screws
Cap Screws & Bolts – Grades 5 &8
Dimensions For Standard Hex Cap Screws
‡Length of a cap screw is measured from the underhead bearing surface to the extreme end of the screw
| Hex Cap Screws (ASME B18.2.1-1996) | |||||||||||||||
| Nominal or Basic Product Diameter |
E | F | G | H | J | L | Y | ||||||||
| Body Diameter |
Width Across Flats |
Width Across Corners |
Head Height |
Wrenching Height |
Thread Length | Transition Thread Length |
|||||||||
| ≤ 6″ | > 6″ | ||||||||||||||
| Max | Min | Basic | Max | Min | Max | Min | Basic | Max | Min | Min | Ref | Ref | Max | ||
| 1/4 | 0.2500 | 0.2500 | 0.24050 | 7/16 | 0.438 | 0.428 | 0.505 | 0.488 | 5/32 | 0.163 | 0.150 | 0.106 | 0.750 | 1.000 | 0.250 |
| 5/16 | 0.3125 | 0.3125 | 0.3065 | 1/2 | 0.500 | 0.489 | 0.577 | 0.577 | 13/64 | 0.211 | 0.195 | 0.140 | 0.875 | 1.125 | 0.278 |
| 3/8 | 0.3750 | .03750 | 0.3690 | 9/16 | 0.562 | 0.551 | 0.650 | 0.628 | 15/64 | 0.243 | 0.226 | 0.160 | 1.000 | 1.250 | 0.312 |
| 7/16 | 0.4375 | 0.4375 | 0.4305 | 5/8 | 0.625 | 0.612 | 0.722 | 0.689 | 9/32 | 0.291 | 0.272 | 0.195 | 1.125 | 1.375 | 0.357 |
| 1/2 | .5000 | 0.5000 | 0.4930 | 3/4 | 0.750 | 0.736 | 0.866 | 0.840 | 5/16 | 0.323 | 0.302 | 0.215 | 1.250 | 1.500 | 0.385 |
| 9/16 | .05625 | 0.5625 | 0.5545 | 13/16 | 0.812 | 0.798 | 0.938 | 0.910 | 23/64 | 0.371 | 0.348 | 0.250 | 1.375 | 1.625 | 0.417 |
| 5/8 | 0.6250 | 0.6250 | 0.6170 | 15/16 | 0.938 | 0.922 | 1.083 | 1.051 | 25/64 | 0.403 | 0.378 | 0.269 | 1.500 | 1.750 | 0.455 |
| 3/4 | 0.7500 | 0.7500 | 0.7410 | 1 1/8 | 1.125 | 1.100 | 1.299 | 1.254 | 15/32 | 0.483 | 0.455 | 0.324 | 1.750 | 2.000 | 0.500 |
| 7/8 | 0.8750 | 0.8750 | 0.8660 | 1 5/16 | 1.312 | 1.285 | 1.516 | 1.465 | 35/64 | 0.563 | 0.531 | 0.378 | 2.000 | 2.250 | 0.556 |
| 1 | 1.0000 | 1.0000 | 0.9900 | 1 1/2 | 1.500 | 1.469 | 1.732 | 1.675 | 39/64 | 0627 | 0.591 | 0.416 | 2.250 | 2.500 | 0.625 |
| 1 1/8 | 1.1250 | 1.1250 | 1.1140 | 1 1/16 | 1.688 | 1.631 | 1.949 | 1.859 | 11/16 | 0.718 | 0.658 | 0.461 | 2.500 | 2.750 | 0.714 |
| 1 1/4 | 1.2500 | 1.2500 | 1.2390 | 1 7/8 | 1.875 | 1.812 | 2.165 | 2.066 | 25/32 | 0.813 | 0.749 | 0.530 | 2.750 | 3.000 | 0.714 |
| 1 1/2 | 1.5000 | 1.5000 | 1.4880 | 2 1/4 | 2.250 | 2.175 | 2.598 | 2.480 | 1 5/16 | 0.974 | 0.902 | 0.640 | 3.250 | 3.500 | 0.833 |
| Tolerance on Length | Nominal Scree Size | Nominal Screw Length | ||||
| Up to 1″ incl | Over 1″ to 2 1/2″ incl | Over 2 1/2″ to 4″ incl | Over 4″ to 6″ incl | Longer than 6″ | ||
| 1/4 to 3/8 | -0.03 | -0.04 | -0.06 | -0.10 | -0.18 | |
| 7/16 and 1/2 | -0.03 | -0.06 | -0.08 | -0.10 | -0.18 | |
| 9/16 to 3/4 | -0.03 | -0.08 | -0.10 | -0.10 | -0.18 | |
| 7//8 and 1 | … | -0.10 | -0.14 | -0.16 | -0.20 | |
| 1 1/8 to 1 1/2 | … | -0.12 | -0.16 | -0.18 | -0.22 | |
| Grade-5 HEX CAP Screw | |
| Description | A cap screw made from medium carbon steel and heat-treated. |
| Applications/ Advantages | Has greater tensile strength than a Grade-2. Yield-to-tensile ratio is the lowest of all heat treated steels. |
| Heat Treatment | Grade-5 cap screws shall be heat treated, oil or water quenched, at the option of the manufacturer, and tempered at a minimum tempering temperature of 800°F. |
| Material | Medium carbon steel. Use of an alloy steel is also acceptable. |
| Core Hardness | 1/4 through 1 in. diameter, all lengths: Rockwell C25 – C34. 1-1/8 through 1-1/2 in. diameter, all lengths: Rockwell C19 – C30. |
| Surface Hardness | 1/4 through 1 in. diameter, all lengths: Rockwell 30N54 maximum. 1-1/8 through 1-1/2 in. diameter, all lengths: Rockwell 30N50 maximum. |
| Proof Load | 1/4 through 1 in. diameter, all lengths: 85,000 psi. 1-1/8 through 1-1/2 in. diameter, all lengths: 74,000 psi. |
| Yield Strength* | 1/4 through 1 in. diameter, all lengths: 92,000 psi. minimum 1-1/8 through 1-1/2 in. diameter, all lengths: 81,000 psi. minimum |
| Tensile Strength | 1/4 through 1 in. diameter, all lengths: 120,000 psi. minimum 1-1/8 through 1-1/2 in. diameter, all lengths: 105,000 psi. minimum |
| Elongation* | 14% minimum (all diameters) |
| Reduction of Area* | 35% minimum (all sizes) |
| Plating | See Appendix-A for plating information. |
| Grade-8 HEX CAP Screw | |
| Description | A cap screw made from medium carbon alloy steel and heat-treated |
| Applications/ Advantages | Has greater tensile strength than a Grade-5. Designed for use in high stress applications. See specifications below for more information on how the Grade-8 exceeds the strength of a Grade-5. |
| Heat Treatment | Grade-8 cap screws shall be heat-treated, oil-quenched and tempered at a minimum temperature of 800°F. |
| Material | Medium carbon alloy steel. Note: For diameters 1/4 through 7/16 inch, it is permissible to use AISI 1541 steel. |
| Core Hardness | 1/4 through 1-1/2 in. diameter, all lengths: Rockwell C33 – C39. |
| Surface Hardness | 1/4 through 1-1/2 in. diameter, all lengths: Rockwell 30N58.6 maximum. |
| Proof Load | 1/4 through 1-1/2 in. diameter, all lengths: 120,000 psi. |
| Yield Strength* | 1/4 through 1-1/2 in. diameter, all lengths: 130,000 psi. minimum |
| Tensile Strength | 1/4 through 1-1/2 in. diameter, all lengths: 150,000 psi. minimum |
| Elongation* | 12% minimum (all diameters) |
| Reduction of Area* | 35% minimum (all sizes) |
| Plating | See Appendix-A for plating information. |