NormCalcEngineering tools
Thread calculator

ISO metric thread

Calculate basic dimensions, tolerances, and limits of metric threads.

ISO965724 · 261
01

Inputs

Internal thread
External thread
02

Results

Geometry, tolerance, inspection

What this calculator does

Thread size, pitch, and tolerance classes produce basic dimensions, limit sizes, and pitch-diameter clearance.

Basic and limit dimensions support design and inspection. Engagement length, coating, gauging, and the actual fastener product remain separate decisions.

Typical tasks
  • Determine 6H/6g limit sizes
  • Check minor and pitch diameters
  • Compare coarse and fine pitches

Related calculators

Bolt proof loadConnect thread stress area to a property class.Tightening torqueTurn thread and target preload into assembly torque.
Design notes and follow-up standards

Check before release

01

Preferred series

Choose diameter and pitch from ISO 261 where possible; special combinations complicate sourcing and inspection.

02

Engagement length

The usual tolerance class assumes an appropriate engagement-length group.

03

Coating

Electroplated or other coatings require a coordinated allowance and inspection concept.

Useful follow-up standards

01

ISO 1502

Gauges and gauging for ISO metric screw threads.

02

ISO 68-1

Basic profile underlying ISO metric geometry.

03

ISO 898 / ISO 3506

Mechanical properties for steel or stainless fasteners.