Socket Screw Tightening Torque Chart (Inch & Metric) – Monster Bolts

Monster Bolts Technical Reference: Socket Screw Tightening Torque Chart

Socket Screw Tightening Torque Chart (Inch & Metric)

This page lists suggested tightening torque values for socket screws in both U.S./Inch and Metric sizes. Figures reflect alloy steel socket screws (U.S.: ASTM A574; Metric: ISO 4762 class 12.9 equivalent).

Standards note: U.S./Inch socket screws are dimensional to ASME B18.3 with mechanical properties per ASTM A574. Metric socket screws follow ISO 4762 geometry / class 12.9 mechanics.
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Official Manufacturer Chart

The chart below is the official Brighton-Best suggested tightening torque guide for socket screws in both inch and metric sizes. For SEO and accessibility, the complete transcribed torque tables follow below.

Brighton-Best socket screw suggested tightening torque chart for inch and metric sizes – Monster Bolts

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Metric – (N·m) Tightening Torque
Dia Socket Head Flat Head Button Head Set Screw Low Head Shoulder Screw
M1.6 0.3 0.08
M2 0.6 0.15
M2.5 1.2 0.42
M3 2 1.4 1.2 0.8
M4 5 3.4 2.2 4 2.8
M5 10 6.8 5.5 4.6 8
M6 16 11 10 7.8 13 7
M8 39 28 24 18 32 12
M10 77 55 47 36 64 29
M12 135 95 82 60 110 57
M14 215 150 62
M16 330 237 150 100
M18 455
M20 650 480 300 240
M22 870
M24 1100 640 470 475 470
M27 1650
M30 2250
M36 3850
M42 6270
U.S./Inch – (in-lb) Tightening Torque
Dia Socket Head Flat Head Button Head Socket Set
Screw		 Low Head Shoulder
Screw
UNC UNF UNC UNF UNC UNF
#0 2.6 1.5 1.5 1
#1 4.5 4.8 2.5 2.5 2.5 2.5 1.8
#2 7.5 8 4.5 4.5 4.5 4.5 1.8
#3 11 12 7 7 7 7 5
#4 16 18 8 8 8 9 5 5
#5 24 24 12 13 12 12 10 9.5
#6 30 34 15 17 16 16 10 9.5
#8 55 58 30 31 30 30 20 19.4
#10 79 90 40 45 45 45 36 33.5
1/4" 204 228 100 110 100 110 87 77.9 50
5/16" 420 456 200 220 200 220 165 156 125
3/8" 744 840 350 400 350 400 290 273 265
7/16" 1200 1308 560 625 430 428
1/2" 1800 2064 850 1000 850 1000 620 615 470
9/16" 2532 2869 1200 1360 620
5/8" 3396 3804 1700 1900 1700 1800 1225 1315 1150
3/4" 6000 6744 3000 3200 2400 2000
7/8" 8256 9204 5000 5400 3600
1" 12480 12960 8000 5000
1-1/4" 24960 27720 13600 9600
1-1/2" 43500 48960 11320
Notes:
  • To convert in-lb to N·m, multiply by 0.113. (N·m to in-lb: × 8.85.)
  • Listed tightening torques are 75% of the torque to yield based on ASTM A574.
  • Values based on unplated and non-lubricated fasteners.
Warning: This chart is a reference guide. Proper torque must be determined by analyzing design parameters, including temperature, plating, lubrication, etc. Short-time tensile, creep, and stress relaxation should be considered for applications where the temperature exceeds 200 °C. Lower ductility, impact strength, and fatigue life must be considered for screws subject to temperatures below -29 °C. All socket screw products are Class 3A Fit except sizes 1-1/4" and larger, which are Class 2A Fit.

FAQ: Socket Screw Torque

Do these values apply to black oxide socket screws?
Yes—values align with alloy steel socket screws (ASTM A574 / ISO 4762 class 12.9). Surface finish and lubrication affect friction; these figures assume unplated, non-lubricated fasteners.
What if my parts are plated or lubricated?
Coatings and lubricants change friction and torque–tension behavior. For critical joints, verify torque via torque–tension testing or consult the coating supplier’s guidance.
Are these inch or metric?
We provide both: a Metric table in N·m and a U.S./Inch table in in-lb.

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Torque data courtesy of Brighton-Best manufacturer reference.

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