Metric Bolt Torque Chart

Verified by Rachel Mayfield, Supply Chain Analyst - April 2026

Torque values for metric hex bolts in property classes 8.8, 10.9, and 12.9. Metric Bolt Torque Chart Values are for dry, unlubricated steel bolts with a nut factor K = 0.20, tightened to 90% of proof load per ISO 898-1. Lubricated bolts (K = 0.15) require roughly 25% less torque. Always confirm torque specs against the fastener manufacturer's data for critical applications.

Size	Pitch (mm)	8.8 (Nm)	10.9 (Nm)	12.9 (Nm)
M3	0.5	1.3	1.8	2.1
M4	0.7	3.0	4.3	5.0
M5	0.8	5.9	8.4	9.8
M6	1.0	10	14	17
M8	1.25	25	35	41
M10	1.5	49	69	81
M12	1.75	85	120	140
M14	2.0	135	190	225
M16	2.0	210	295	345
M18	2.5	285	400	470
M20	2.5	405	570	670
M22	2.5	550	780	910
M24	3.0	690	970	1140
M27	3.0	1050	1470	1720
M30	3.5	1400	1960	2300

How to use the metric bolt torque chart

Find the bolt size in the left column, then read across to the property class stamped on the bolt head. Property class 8.8 is the most common grade for general engineering. Class 10.9 is used in automotive and high-strength structural joints. Class 12.9 is the highest standard grade, typically socket head cap screws.

These values assume clean, dry threads with no lubricant. If you're using oil, grease, or thread paste, reduce the torque by 20-30% or use the K-factor method: T = K x d x F, where T is torque in Nm, d is nominal diameter in metres, and F is the target clamp force in newtons.

For flange bolts or bolts with prevailing torque locknuts, add the prevailing torque to the values shown. Always torque in a star pattern on multi-bolt flanges.

Related standards

• ISO 898-1 - Mechanical properties of fasteners made of carbon steel and alloy steel (bolts, screws, studs)
• ISO 898-2 - Mechanical properties of fasteners (nuts with specified proof load)
• VDI 2230 - Systematic calculation of bolted joints
• BS EN ISO 4014 - Hexagon head bolts, product grades A and B
• BS EN ISO 4762 - Hexagon socket head cap screws