Bolt torque by size and grade
Pick the bolt size, then its grade, then the thread condition: a 1/2-13 Grade 8 bolt is 107 ft-lb dry but 80 ft-lb oiled for the same clamp load. Every value here is calculated from SAE J429 or ISO 898-1 proof loads with the nut factor printed beside it.
Contents5 sections
Key takeaways
- Torque depends on size, grade and thread condition. Get all three right before reading a number.
- Lubricated threads need about 25% less torque than plain dry steel for the same clamp load 1.
- Even a correct torque gives about ±25% scatter in bolt tension 2.
- When the equipment maker publishes a torque, use theirs.
This section gives tightening torque for inch bolts from 1/4 in to 1 in and metric bolts from M3 to M30. All of it comes from one method: T = K × D × F, with the clamp load F set at 75% of the bolt’s proof load 1.
How to find the right value
Size
Measure the diameter and the thread. If you are not sure whether a bolt is inch or metric, the thread pitch chart lists TPI and pitch side by side, and the socket size chart shows the wrench that fits each head.
Grade
Read the head. Three radial lines mean SAE Grade 5, six mean Grade 8, and metric heads carry the class number, such as 8.8 or 10.9 1. The bolt grades page explains the marks, and the bolt grade identification tool walks you through them.
Condition
Decide whether the threads are plain and dry, zinc-plated, oiled, or coated with anti-seize. This changes the torque more than most people expect. Torque needed for the same tension falls as K drops from 0.20 dry to 0.15 oiled 1 and 0.11 with moly paste 3.
Where to go next
- The SAE bolt torque chart covers Grades 2, 5 and 8 on one page. The metric bolt torque chart covers classes 4.6, 8.8, 10.9 and 12.9.
- Each size page adds fine threads, every thread condition and the clamp load.
- The bolt torque calculator handles sizes, grades or nut factors that are not in the tables.
These tables do not apply to structural bolts in pretensioned joints, where RCSC does not allow torque values taken from tables 4. Use the structural bolting section for those.
In this section
- SAE chartSAE bolt torque chart for Grade 2, 5 and 8 from 1/4 in to 1 in, dry and lubricated, calculated from SAE J429 proof loads with the nut factor shown.
- Metric chartMetric bolt torque chart for classes 4.6, 8.8, 10.9 and 12.9 from M3 to M30, dry and lubricated, in N·m and ft-lb from ISO 898-1 proof loads.
- Bolt gradesRead SAE radial-line marks, metric class stamps and A325/A490 structural stamps, with SAE vs metric strength equivalents and which nut to pair with each grade.
- Thread pitch chartThread pitch chart for UNC and UNF inch bolts and ISO metric coarse and fine threads, with the tensile stress area each torque calculation uses.
- Socket size chartSocket sizes for inch hex cap screws, heavy hex structural bolts and metric bolts, including M10, M12, M14 and M22, where ISO and DIN heads differ.
Sources
- 1
- 2
- 3Henkel Corporation (LOCTITE), LOCTITE LB 8012 Moly Paste TDS, April 2015Checked 21 Oct 2026
- 4
Spotted a value that doesn’t match its source? Report an error
Related
- SAE chartSAE bolt torque chart for Grade 2, 5 and 8 from 1/4 in to 1 in, dry and lubricated, calculated from SAE J429 proof loads with the nut factor shown.
- Metric chartMetric bolt torque chart for classes 4.6, 8.8, 10.9 and 12.9 from M3 to M30, dry and lubricated, in N·m and ft-lb from ISO 898-1 proof loads.
- Bolt gradesRead SAE radial-line marks, metric class stamps and A325/A490 structural stamps, with SAE vs metric strength equivalents and which nut to pair with each grade.
- Bolt torque calculatorBolt torque calculator for SAE and metric bolts by size, thread, grade and lubrication, using T = K × D × F with the proof loads from SAE J429 and ISO 898-1.