ISO 261 Metric Thread Series

Preferred diameter and pitch combinations for metric threads.

Referenced for metric designation and pitch-plan context in engineering explanations.

Use related standards and concepts to connect profile geometry, designation planning, dimensions, and tolerance interpretation.

Use BoltLab tools and charts for workflow interpretation while final release values come from approved standards documents.

What This Standard Covers

  • Specifies preferred metric diameter and pitch combinations.
  • Frames coarse and fine designation planning before tolerance assignment.
  • Creates a consistent baseline for tooling and part interoperability.

When Engineers Use It

  • Selecting standard pitch options in product development.
  • Normalizing design choices across suppliers and geographies.
  • Preparing design data before tolerance class selection.

ISO 261 planning quick table

Decision pointISO 261 roleDownstream dependency
Designation selectionPreferred diameter and pitch planningFeeds ISO 724 dimensional context
Series strategyCoarse/fine planning baselineFeeds ISO 262 selected fine combinations
Specification handoffNormalizes thread notationFeeds ISO 965 tolerance selection

Related Standards

  • ISO 261
  • ISO 262
  • ISO 724
  • ISO 965-1

Related Concepts

Related tools and charts

FAQ

What does ISO 261 Metric Thread Series primarily define?

ISO 261 Metric Thread Series provides engineering guidance for one part of thread specification workflow and is used alongside related ISO standards rather than in isolation.

When do engineers typically use this standard?

Engineers use it when selecting, validating, or reviewing thread specifications and coordinating drawings, metrology, and production decisions.

How does BoltLab help interpret this standard?

BoltLab tools and charts accelerate identification, comparison, and tolerance-context checks while final release values still come from approved standards documents.

Does this page reproduce copyrighted standards tables?

No. BoltLab provides public-summary explanations, engineering context, and workflow guidance without reproducing protected standards text.

Which related standard should I review next?

Use the Related Standards section to move through profile, designation, dimensions, and tolerance standards in a coherent sequence.

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