Additional Specification
- CAP SCREW THREAD INCH & METRIC
- INCH FASTENERS
- INCH SIZE BOLT HEAD/WRENCH SIZE
- US TAP AND DRILL BIT SIZE
- INCH CAP SCREW STRENGTH
- TORQUE VALUES FOR GRADES 2, 5, 8, AND 9 BOLTS – COARSE THREAD
- TORQUE VALUES FOR GRADES 2, 5, 8, AND 9 BOLTS – FINE THREAD
CAP SCREW THREAD INCH & METRIC
| Inch Size Coarse(UNC) Fine(UNF) | Decimal Equivalent | Closest Metric Size | Decimal Conversion |
|---|---|---|---|
| 1/4-20 | .250 | M6 X 1.0 | .236″ |
| 1/4-28 | .250 | M6 X .075 | .236 |
| 5/16-18 | .3125 | M8 X 1.25 | .315 |
| 5/16-24 | .3125 | M8 X 1.0 | .315 |
| 3/8-16 | .375 | M10 X 1.5 | .394 |
| 3/8-24 | .375 | M10 X 1.25 | .394 |
| 7/16-14 | .4375 | ||
| 7/16-20 | .4375 | ||
| 1/2-13 | .500 | M12 X 1.75 | .472 |
| 1/2-20 | .500 | M12 X 1.25 | .472 |
| 9/16-12 | .5625 | M14 X 2.0 | .551 |
| 9/16-18 | .5625 | M14 X 1.5 | .551 |
| 5/8-11 | .625 | M16 X 2.0 | .630 |
| 5/8-18 | .625 | M16 X 1.5 | .630 |
| 3/4-10 | .750 | M20 X 2.5 | .787 |
| 3/4-16 | .750 | M20 X 1.5 | .787 |
| 7/8-9 | .875 | M22 X 2.5 | .866 |
| 7/8-14 | .875 | M22 X 1.5 | .866 |
| 1-8 | 1.00 | M24 X 3.0 | .945 |
| 1-12 | 1.00 | M24 X 2.0 | .945 |
| 1-14 | 1.00 | ||
| 1 1/8-7 | 1.125 | ||
| 1 1/8-12 | 1.125 | ||
| 1 1/4-7 | 1.25 | M30 X3.5 | 1.181 |
| 1 1/4-12 | 1.25 | M30 X 2.0 | 1.181 |
STANDARD THREAD LENGTH FOR HEX HEAD CAP SCREWS
INCH FASTENERS
| Dia | Lengths Threaded to the Head | Lengths with Partial Threads | Min. & Max Thread Lengths |
|---|---|---|---|
| Lengths Up To | Lengths | Min.-Max. | |
| 1/4 | 1 1/8 | 1-1/4 to 6 | 3/4 – 1.0 |
| 5/16 | 1 1/4 | 1-5/16 to 6 | 7/8 – 1.153 |
| 3/8 | 1 3/8 | 1-1/2 to 6 | 1 – 1.312 |
| 7/16 | 1 5/8 | 1-3/4 to 6 | 1 1/8 – 1.482 |
| 1/2 | 1 3/4 | 1-7/8 to 6 | 1 1/4 – 1.635 |
| 9/16 | 2 | 2-1/8 to 6 | 1 3/8 – 1.792 |
| 5/8 | 2 1/8 | 2-1/4 to 6 | 1 1/2 – 1.955 |
| 3/4 | 2 1/2 | 2-5/8 to 6 | 1 3/4 – 2.250 |
| 7/8 | 2 3/4 | 2-7/8 to 6 | 2 – 2.556 |
| 1 | 3 | 3-1/8 to 6 | 2 1/4 – 2.875 |
| 1 1/8 | 3 1/2 | 3-5/8 to 6 | 2 1/8 – 3.214 |
| 1 1/4 | 3 3/4 | 3-7/8 to 6 | 2 3/4 – 3.464 |
| 1 3/8 | 4 1/4 | 4-5/16 to 6 | 3 – 3.833 |
| 1 1/2 | 4 1/2 | 4-5/8 to 6 | 3 1/4 – 4.083 |
| 1 3/4 | 5 1/2 | 5-1/4 to 6 | 3 3/4 – 4.75 |
| 2 | 5 3/4 | 5-7/8 to 6 | 4 1/4 – 5.361 |
| 2 1/4 | 6 1/2 | 6-5/8 to 12 | 5 – 5.861 |
| 2 1/2 | 7 1/8 | 7-1/8 to 12 | 5 1/2 – 6.5 |
INCH SIZE BOLT HEAD/WRENCH SIZE
| Bolt Diameter | Hex Bolt Lag Bolt Square Bolt | Heavy Hex Bolts |
|---|---|---|
| #6 | 1/4 | |
| #8 | 1/4 | |
| #10 | 5/16 | |
| #12 | 5/16 | |
| 1/4 | 7/16 or 3/8 | |
| 5/16 | 1/2 | |
| 3/8 | 9/16 | |
| 7/16 | 5/8 | |
| 1/2 | 3/4 | 7/8 |
| 9/16 | 13/16 | |
| 5/8 | 15/16 | 1 /16 |
| 3/4 | 1 1/8 | 1 1/4 |
| 7/8 | 1 5/16 | 1 7/16 |
| 1 | 1 1/2 | 1 5/8 |
| 1 1/8 | 1 11/16 | 1 3/4 |
| 1 1/4 | 1 7/8 | 2 |
US Tap and Drill Bit Size
| Tap | Drill Bit Size (Optional Letter/ Number) |
|---|---|
| 0-80 | 3/64 |
| 1-64 | 53 |
| 2-56 | 50 |
| 3-48 | 47 |
| 4-40 | 3/32 |
| 5-40 | 38 |
| 6-32 | 7/64 (35) |
| 8-32 | 29 |
| 10-24 | 5/32 (25) |
| 10-32 | 5/32 (21) |
| 12-24 | 11/64 (16) |
| 1/4-20 | 13/64 (7) |
| 1/4-28 | 7/32 (3) |
| 5/16-18 | 17/64 (F) |
| 5-16-24 | I |
| 3/8-16 | 5/16 |
| 3/8-24 | 21/64 (Q) |
| 7/16-14 | 23/64 (U) |
| 7/16-20 | 25/64 |
| 1/2-13 | 27/64 |
| 1/2-20 | 29/64 |
| 9/16-12 | 31/64 |
| 9/16-18 | 33/64 |
| 5/8-11 | 17/32 |
| 5/8-18 | 37/64 |
| 3/4-10 | 21/32 |
| 3/4-16 | 11/16 |
INCH CAP SCREW STRENGTH
| Inch Grade | Tensile Strength (Min) | Yield Strength, min, (psi) | Full Size Proofload, (psi) | Material | Treatment |
|---|---|---|---|---|---|
| Grade 2 | Carbon Steel | None | |||
| 1/4 thru 3/4 | 74,000 | 57,000 | 55,000 | ||
| >3/4 thru 1 1/2 | 60,000 | 36,000 | 33,000 | ||
| Grade 5 | Carbon Steel | Quenched & Tempered | |||
| 1/4 thru 1 | 120,000 | 92,000 | 85,000 | ||
| >1 thru 1 1/2 | 105,000 | 81,000 | 74,000 | ||
| Grade 8 | Alloy Steel | Quenched & Tempered | |||
| 1/4 thru 1 1/2 | 150,000 | 130,000 | 120,000 |
Suggested Torque Values & Clamp Loads
Torque Values for Grades 2, 5, 8, and 9 Bolts – Coarse Thread
| SAE Gr. 2 | SAE Gr. 5 | SAE Gr. 8 | Grade 9 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Nominal Size & tpi | Tensile Stress Area (sq in) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
| 1/4-20 | 0.0318 | 859 | 37 (in-lbs) |
2029 | 86 (in-lbs) |
2864 | 122 (in-lbs) |
3357 | 143 (in-lbs) |
| 5/16-18 | 0.0524 | 1416 | 75 | 3342 | 178 | 4719 | 251 | 5531 | 294 |
| 3/8-16 | 0.0775 | 2092 | 11 (ft-lbs) | 4940 | 26 (ft-lbs) | 6974 | 37 (ft-lbs) | 8174 | 43 (ft-lbs) |
| 7/16-14 | 0.14063 | 2870 | 18 | 6777 | 42 | 9568 | 59 | 11214 | 70 |
| 1/2-13 | 0.1419 | 3831 | 27 | 9046 | 64 | 12771 | 90 | 14969 | 106 |
| 9/16-12 | 0.1819 | 4912 | 39 | 11599 | 92 | 16375 | 130 | 19193 | 153 |
| 5/8-11 | 0.226 | 6102 | 54 | 14408 | 128 | 20340 | 180 | 23840 | 211 |
| 3/4-10 | 0.3345 | 9030 | 96 | 21322 | 227 | 30101 | 320 | 35281 | 375 |
| 7/8-9 | 0.4617 | 12467 | 155 | 29436 | 365 | 41556 | 515 | 48707 | 604 |
| 1-8 | 0.6057 | 16355 | 232 | 38616 | 547 | 54517 | 772 | 63899 | 905 |
| 1 1/4-7 | 0.9691 | 26166 | 463 | 53786 | 952 | 87220 | 1545 | 102229 | 1810 |
| 1 1/2-6 | 1.4053 | 37942 | 806 | 77991 | 1657 | 126473 | 2688 | 148237 | 3150 |
Torque Values for Grades 2, 5, 8, and 9 Bolts – Fine Thread
| SAE Gr. 2 | SAE Gr. 5 | SAE Gr. 8 | Grade 9 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Nominal Size & tpi | Tensile Stress Area (sq in) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
Clamp Load (lb) |
Tightening Torque (in-oz) |
| 1/4-28 | 0.0364 | 982 | 42 (in-lbs) |
2319 | 99 (in-lbs) |
3274 | 139 (in-lbs) |
3837 | 163 (in-lbs) |
| 5/16-24 | 0.0581 | 1568 | 83 | 3702 | 197 | 5226 | 278 | 6125 | 325 |
| 3/8-24 | 0.0878 | 2371 | 13 (ft-lbs) | 5599 | 30 (ft-lbs) | 7905 | 42 (ft-lbs) | 9265 | 49 (ft-lbs) |
| 7/16-20 | 0.1187 | 3205 | 20 | 7568 | 47 | 10684 | 66 | 12523 | 78 |
| 1/2-20 | 0.16 | 4319 | 31 | 10197 | 72 | 14396 | 102 | 16873 | 120 |
| 9/16-18 | 0.203 | 5480 | 44 | 12940 | 103 | 18268 | 146 | 21412 | 171 |
| 5/8-18 | 0.256 | 6911 | 61 | 16317 | 144 | 23036 | 204 | 27000 | 239 |
| 3/4-16 | 0.373 | 10070 | 107 | 23776 | 253 | 33566 | 357 | 39343 | 418 |
| 7/8-14 | 0.5095 | 13756 | 171 | 32479 | 403 | 45853 | 568 | 53743 | 666 |
| 1-14 | 0.6799 | 18357 | 260 | 43343 | 614 | 61190 | 867 | 71720 | 1016 |
| 1 1/4-12 | 1.0729 | 28970 | 513 | 59548 | 1055 | 96565 | 1710 | 113182 | 2004 |
| 1 1/2-12 | 1.581 | 37942 | 907 | 87747 | 1865 | 142292 | 3024 | 166778 | 3544 |
All material in these charts are theoretical only. Use by anyone in an actual application is voluntary.
Torque Valuses are calculated from the formula – T = KDF, where
K = 0.17 for zinc plated, dry conditions
D = Nominal Diameter
F = Clamp Load
Clamp load calculated as 75% of the proof load when specified by the standard.