Bolt & Nut Torque Chart
Tightening torque sets the clamp load that holds a joint together and keeps the nut from loosening. The right value depends on the bolt diameter, grade, and whether the threads are dry or lubricated. This chart gives reference torque for common coarse-thread sizes, along with the factors that change it.
Reference Torque Chart (Coarse Thread, Dry)
| Size | Grade 2 (ft-lb) | Grade 5 (ft-lb) | Grade 8 (ft-lb) |
|---|---|---|---|
| 1/4-20 | 4 | 8 | 12 |
| 5/16-18 | 8 | 17 | 24 |
| 3/8-16 | 15 | 30 | 45 |
| 7/16-14 | 24 | 50 | 70 |
| 1/2-13 | 37 | 75 | 110 |
| 9/16-12 | 53 | 110 | 150 |
| 5/8-11 | 75 | 150 | 220 |
| 3/4-10 | 130 | 265 | 375 |
| 7/8-9 | 125 | 430 | 600 |
| 1-8 | 190 | 640 | 900 |
Approximate clamp-load-based values for clean, dry, zinc-plated steel, coarse thread. Grade 2 above 3/4 inch drops because larger low-grade bolts are uncommon and de-rated. Use the bolt manufacturer's data and the project specification for design.
What Changes the Torque
- Lubrication: oil, wax, or anti-seize reduces friction — a lubricated joint needs roughly 15–25% less torque for the same clamp load. Over-torquing a lubed bolt to the dry value can yield or snap it.
- Grade: higher-grade bolts (and matched nuts) take more torque — never apply Grade 8 torque to a Grade 2 or 5 bolt.
- Lock nuts: prevailing-torque (nylock, Stover) nuts add running torque; add the nut's prevailing torque to the seating torque, or follow the nut maker's spec.
- Structural bolts: A325/A490 connections use turn-of-nut, DTI washers, or calibrated tension — not a generic torque value.
Make sure the nut grade matches the bolt before torquing — see our Nut Grade & Bolt-Matching Guide.
Frequently Asked Questions
How much should I torque a 1/2-13 Grade 5 bolt?
As a dry reference, about 75 ft-lb for a clean, plated Grade 5 1/2-13 fastener. Reduce roughly 15–25% if the threads are lubricated, and always defer to the manufacturer's or engineer's specification for your joint.
Should I torque to dry or lubricated values?
Match the value to the condition. Dry charts assume clean, unlubricated threads. If you apply oil, wax, or anti-seize, use the lubricated specification (roughly 15–25% lower torque) or you risk over-tensioning the bolt.
Do lock nuts change the torque?
Yes. Prevailing-torque lock nuts (nylock, Stover) add running torque that must be added to the seating torque, or you follow the nut manufacturer's combined spec. Otherwise the joint ends up under-tensioned.
How are structural (A325) bolts tightened?
Not by generic torque. Structural connections use turn-of-nut, direct-tension-indicator (DTI) washers, or calibrated-wrench tension to reach a specified bolt pretension per the project spec.
Need Matched Bolts & Nuts?
Grade 2/5/8 and structural fasteners with the correct matching nuts, by the piece or in bulk.