Metric Socket Screw Torque & Specifications (M3–M30)

Reference torques and dimensional specs for common metric socket fasteners. Values shown are for coarse threads and intended as Recommended Seating Torque (R.S.) unless otherwise noted (socket set screws use Proof Torque). Use as a guide only—application variables such as lubrication, plating/coating, temperature, joint bearing area, and thread condition will change results.

Quick notes:
  • Figures are for dry (unlubricated) condition unless stated. Light lubrication can reduce torque by 15–25% (or more) for the same preload.
  • Values apply to coarse pitch only. Fine threads typically require slightly different torques.
  • Always verify joint requirements; consider using a torque + angle method on critical joints.
  • Need pitch reference? Compare Metric Thread Pitch vs. US TPI.

Torque Summary (Alloy Steel Socket Screws)

Size Socket Head Cap, 12.9 Low Head Socket Cap, 10.9 Flat Head Cap, 12.9 Button Head Cap, 12.9 Socket Set Screw, 45H*
M3 2.20 Nm 1.15 Nm 1.35 Nm 1.35 Nm 0.90 Nm
M4 4.83 Nm 2.70 Nm 3.10 Nm 3.10 Nm 2.50 Nm
M5 10.0 Nm 5.40 Nm 6.10 Nm 6.10 Nm 5.00 Nm
M6 16.8 Nm 9.15 Nm 10.50 Nm 10.5 Nm 8.50 Nm
M8 41.0 Nm 22.0 Nm 26 Nm 26 Nm 20.0 Nm
M10 81.0 Nm 44.0 Nm 52 Nm 52 Nm 40.0 Nm
M12 142 Nm 77.0 Nm 90 Nm 90 Nm 65.0 Nm
M14 226 Nm 122 Nm 143 Nm   65.0 Nm
M16 350 Nm 190 Nm 225 Nm 225 Nm 160 Nm
M18 485 Nm 262 Nm     310 Nm
M20 685 Nm 371 Nm 440 Nm   310 Nm

* Socket set screws shown with Proof Torque (45H).

Socket Head Cap Screws, DIN 912 / ISO 4762

Size Max Head Width Max Head Height Hex Key Size R.S. Torque (Nm) 12.9 R.S. Torque (Nm) 10.9
M1.6 3.14mm 1.60mm 1.5mm 0.30 0.25
M2 3.98mm 2.0mm 1.5mm 0.63 0.5
M2.5 4.68mm 2.5mm 2.0mm 1.27 1.03
M3 5.68mm 3.0mm 2.5mm 2.20 1.83
M4 7.22mm 4.0mm 3mm 4.83 4.27
M5 8.72mm 5.0mm 4mm 10.0 8.64
M6 10.22mm 6.0mm 5mm 16.8 14.7
M8 13.27mm 8.0mm 6mm 41.0 35.6
M10 16.27mm 10.0mm 8mm 81.0 70.6
M12 18.27mm 12.0mm 10mm 142 123
M14 21.33mm 14.0mm 12mm 226 195
M16 24.33mm 16.0mm 14mm 350 305
M18 27.33mm 18.0mm 14mm 485 420
M20 30.33mm 20.0mm 17mm 685 596
M22 33.39mm 22.0mm 17mm 930 811
M24 36.39mm 24.0mm 19mm 1180 1031
M27 40.39mm 27.0mm 19mm 1730 1508
M30 45.39mm 30.0mm 22mm 2380 2048
M33 50.39mm 33.0mm 24mm 3262 2787
M36 54.46mm 36.0mm 27mm 4190 3580
M39 58.46mm 39.0mm 27mm 5420 4633

Socket head cap screws are ideal where high strength and compact head clearance are required; head may protrude or be used in counterbores.

Low Head Socket Cap Screws, DIN 7984 (10.9)

Size Max Head Width Max Head Height Hex Key Size R.S. Torque (Nm) 10.9
M3 5.5mm 2.0mm 2mm 1.15
M4 7.0mm 2.8mm 2.5mm 2.70
M5 8.5mm 3.5mm 3mm 5.40
M6 10.0mm 4.0mm 4mm 9.15
M8 13.0mm 5.0mm 5mm 22.0
M10 16.0mm 6.0mm 7mm 44.0
M12 18.0mm 7.0mm 8mm 77.0
M14 21.0mm 8.0mm 10mm 122
M16 24.0mm 9.0mm 12mm 190
M18 27.0mm 10.0mm 12mm 262
M20 30.0mm 11.0mm 14mm 371

Low head socket caps are for tight-clearance joints; due to reduced head height, avoid use in high-tension critical joints unless validated.

Button Head Socket Cap Screws, ISO 7380 / DIN 9427

Size Max Head Width Max Head Height Hex Key Size R.S. Torque (Nm) 12.9 R.S. Torque (Nm) 10.9
M3 5.70mm 1.65mm 2mm 1.35 1.15
M4 7.60mm 2.20mm 2.5mm 3.10 2.70
M5 9.50mm 2.75mm 3mm 6.10 5.40
M6 10.50mm 3.30mm 4.0mm 10.5 9.15
M8 14.0mm 4.40mm 5mm 26.0 22.0
M10 17.50mm 5.50mm 6mm 52.0 44.0
M12 21.0mm 6.60mm 8mm 90.0 77.0
M16 28.0mm 8.80mm 10mm 225 190

Button heads offer a wider bearing surface and rounded profile to reduce snagging; not intended for highest-tension joints.

Flat Head Socket Cap Screws, DIN 7991 / ISO 10642

Size Thread Pitch Max Head Width Hex Key Size R.S. Torque (Nm) 12.9 R.S. Torque (Nm) 10.9
M3 0.50 6.72mm 2mm 1.35 1.15
M4 0.70 8.96mm 2.5mm 3.10 2.70
M5 0.80 11.20mm 3mm 6.10 5.40
M6 1.00 13.44mm 4.0mm 10.5 9.15
M8 1.25 17.92mm 5mm 26.0 22.0
M10 1.50 22.40mm 6mm 52.0 44.0
M12 1.75 26.88mm 8mm 90.0 77.0
M14 2.00 30.80mm 10mm 143 122
M16 2.00 33.60mm 10mm 225 190
M20 2.50 40.32mm 12mm 440 371

Countersunk flat heads install flush; ensure adequate countersink bearing area to avoid embedment and loss of preload.

Socket Set Screws, DIN 916 / ISO 4029 (Proof Torque, 45H)

Size Thread Pitch Hex Key Size Proof Torque (Nm) 45H
M3 0.50 1.5mm 0.90
M4 0.70 2mm 2.50
M5 0.80 2.5mm 5.00
M6 1.00 3mm 8.50
M8 1.25 4.0mm 20.0
M10 1.50 5mm 40.0
M12 1.75 6mm 65.0
M14 2.00 6mm 65.0
M16 2.00 8mm 160
M18 2.50 10mm 310
M20 2.50 10mm 310

Set screws (cup point) are used to secure components on shafts. Proof torque reflects strength of a 45H part—not a seating torque for clamped joints.

Related Guides & Tools

Torque & Specification FAQs

Are these torques dry or lubricated?

Unless specified, values are for dry condition. Lubrication reduces friction and can lower the torque required to reach the same preload—often by 15–25% (or more depending on the lubricant and finish).

Do these numbers apply to fine threads?

No. Tables above assume coarse pitch. Fine threads can use different torque/preload relationships; verify per application.

What’s the difference between Recommended Seating Torque and Proof Torque?

R.S. Torque is a practical seating guideline for clamping. Proof Torque (set screws) relates to the strength/hardness class and is not a clamp load guideline.

Can I convert Nm to in-lb or ft-lb?

Yes: 1 Nm ≈ 8.85 in-lb and 1 Nm ≈ 0.7376 ft-lb. Multiply accordingly.

Should I use threadlocker?

For vibration or cyclic loading, a medium-strength threadlocker or prevailing-torque nut can help. Note threadlocker and plating can alter friction—adjust torque as needed.

Join our Monster Bolts Newsletter

Exclusive discounts sent out to our subscribers.