Related Resources: mechanical-tolerances

Composite Position Tolerance Calculator GD&T for External FOS

Mechanical Engineering Tolerances Resources

GD&T Composite Position Tolerance Calculator for Dimensional Inspection:

External Feature of Size - post, tab, pipe, etc...

Composite Feature Control Frame


  • Applies to an External Features of Size (Tab, Boss Projection etc..)
  • PLTZF tolerance applied at MMC
  • FRTZF tolerance applied at MMC
  • All dimensional unit applied with uniform units - all inches, mm, m, etc.
  • Datum applied at RFS
  • Datums are normally othogonal to FOS for PLTZF
  • Complex, non othogonal datums not supported 
  • FRTZF datum is perpendicular to features
  • X and Y measurements taken with datum's established
  • Up to fifteen (15) features can be calculated
  • Hole feature #1 is used as the origin for the FRTZF position tolerance calculations


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For information on the equations used in this calculator, see:

Geometric Boundaries, II - The Interpretation and Application of GD&T per. ASME Y14.5-2009