Circular runout limits variation at each circular cross-section as a part rotates 360° about a datum axis. Each section is checked separately; the readings are not combined into one full-length surface check. A datum axis is required so the measured variation represents rotation about the intended reference.
Datum required
Yes — a datum axis
MMC / LMC applicable
No — surface variation control
Control type
Runout
What it controls
At each measured section, total indicator variation during rotation is limited by the callout.
Typical features
Shafts, gears, journals, axles, drills and rotating surfaces where wobble, vibration or uneven contact matters.
INTERACTIVE APPLICATION
GD&T circular runout example: rotating shaft land
WITHOUT CIRCULAR RUNOUT
Individual cross-sections assessed separately
Size checks alone do not limit rotational surface variation about datum A.
Limitations
Wobble or uneven contact may remain even when the diameter meets its size tolerance.
WITH CIRCULAR RUNOUT
Individual cross-sections assessed separately
The 0.05 frame limits rotational variation relative to datum A.
Advantages
Check sections separately. Passing circular runout does not mean the whole cylinder passes total runout.
INTERPRETATION
Individual cross-sections assessed separately
Two concentric circles define a 0.05 radial zone at each section about datum axis A.
Interpretation
Check sections separately. Passing circular runout does not mean the whole cylinder passes total runout.
01 / PURPOSE
Why is Circular runout used?
Use circular runout to limit section-wise wobble relative to the rotation axis. It combines local roundness and coaxiality effects, but does not by itself control taper or straightness along the full length. Size still needs its own tolerance.
02 / APPLICATION
Where is Circular runout used?
Shafts, gears, journals, axles, drills and rotating surfaces where wobble, vibration or uneven contact matters.
03 / DRAWING
How is Circular runout used?
Identify a cylindrical datum feature A to establish the rotation axis. Attach the runout frame to the surface being controlled, and keep the diameter size tolerance separate.
Circular runout drawing examplerotating shaft land
Datum A is attached to the size-dimension line for the cylindrical reference feature. The frame leader identifies the controlled surface.
How to read the frame
The single-arrow circular runout symbol identifies the control. 0.05 is the maximum permitted indicator variation in drawing units. A identifies the datum axis.
04 / VALUES
Commonly defined variable values
The illustrated value limits indicator variation during rotation about the datum axis; it is not a universal process grade.
Scroll the table sideways to see every column.
Illustrative circular runout tolerances for early design discussion
Application
Illustrative starting value
Example feature
Notes / caution
Rotating Shaft Land
0.05 mm (example only)
rotating shaft land
Illustrative only; account for bearing and datum setup.
These are planning examples, not universal rules or guaranteed process capabilities. Set the actual tolerance from function, size, length, process capability, inspection method and the standard specified on the drawing.
CHOOSING A CONTROL
Runout vs total runout: which one to use?
Use circular runout for individual circular cross-sections: each has a 2D tolerance zone checked separately. Use total runout when the full surface matters: its 3D zone covers the whole cylindrical surface.
Total runout is generally more restrictive because it also limits taper and form variation along the surface. Both reference a datum axis; neither replaces the size tolerance.
Rotate the part 360° about the datum axis with the indicator touching one cross-section. The highest minus lowest reading at that section must not exceed the circular runout tolerance. Repeat at other sections separately.
Locate the datum feature in a suitable chuck, collet or other datum simulator.
Use a suitable contact direction and check the coverage required by the drawing.
Simplified setup for the rotating shaft land; use the drawing's specified inspection method.
ASME Y14.5-2018 (R2024)
ASME Y14.5 circular runout is a section-wise surface control relative to a datum axis.
Engineering toolkit · Prototype