MANUFACTURING – METROLOGY & QUALITY CONTROL CALCULATOR
Coordinate Tolerance Zone
A precise tool.
What is the Coordinate Tolerance Zone & How does it work?
In Geometric Dimensioning & Tolerancing (GD&T), a coordinate tolerance zone defines the permissible variation of a feature’s location relative to its datum(s). The zone is expressed as a geometric shape—typically a cylinder, sphere, or rectangular prism—whose dimensions are derived from the specified tolerance value.
Different feature types (position, straightness, flatness, profile of a line, profile of a surface) use distinct zone constructions. For a position tolerance, the zone is a cylindrical volume centered on the true position; for straightness it is a rectangular band along the feature’s axis. The choice of datum reference and material condition (MMC, LMC, RFS) further influences the size and orientation of the zone.
The basic calculation for a symmetric zone is to halve the linear tolerance, yielding the radius (or half‑width) of the zone. This radius is then applied to the selected coordinate system to visualise the allowable region.
R = frac{T}{2}
R = radius of the tolerance zone (mm)
Parameters
Result
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Frequently Asked Questions
What is a coordinate tolerance zone in GD&T?
A coordinate tolerance zone defines the permissible variation of a feature’s location relative to its datum(s) in Geometric Dimensioning & Tolerancing.
How do you determine the shape of the tolerance zone?
The shape of the tolerance zone is typically a cylinder, sphere, or rectangular prism, derived from the specified tolerance value and feature type.
What types of features use different zone constructions in GD&T?
Position, straightness, flatness, profile of a line, and profile of a surface are examples of feature types that use distinct zone constructions in GD&T.
For what type of tolerance is the zone a cylinder?
The zone is a cylinder for position tolerances in Geometric Dimensioning & Tolerancing.
Can you explain how datum(s) affect the coordinate tolerance zone?
Datum(s) serve as reference points or surfaces from which the location of a feature is measured, defining the boundaries of the permissible variation within the tolerance zone.
Results are for informational purposes only and do not constitute professional advice.