AtlasCalcsUtility Calculation Suite
2026-07-30 8 min

Runout Calculator

Calculate circular runout, total runout, and tolerance compliance from indicator measurements per ISO 1101 and ASME Y14.5 standards.

Calculator

Unit System
Max Indicator Reading (mm)
Min Indicator Reading (mm)
Datum Diameter (mm)
Rotational Speed (rpm)
Tolerance Value (mm)

Results

Optimal

Total Runout (TIR)

0.1000mm

Total indicator reading — the full range of indicator movement

Circular Runout (FIM)

0.1000mm

Full indicator movement — the measured runout value

Average Deviation

0.0700mm

Average of indicator readings (mean surface position)

Deviation Ratio

0.6667

Ratio of measured runout to tolerance. Pass if ≤ 1.0

Status

Pass

Accept/Reject based on runout deviation ratio

Visualizations

Results Overview

0.1mmTotal Runout
0.1mmCircular Runout
0.1mmAverage Deviation
0.7mmDeviation Ratio

Formula

Runout is the total variation of a surface measured by a dial indicator as the part rotates 360° about the datum axis. TIR (Total Indicator Reading) equals the difference between maximum and minimum readings.

TIR = MaxReading - MinReading

Alternative Form

CircularRunout = TIR (FIM)

Variables

SymbolNameUnitDescription
R_maxMax Indicator ReadingmmMaximum dial indicator reading during one complete revolution
R_minMin Indicator ReadingmmMinimum dial indicator reading during one complete revolution
FIMFull Indicator MovementmmTotal range of indicator movement (synonymous with TIR)
tTolerancemmSpecified runout tolerance value

Explanation

Circular runout controls surface variation in a single cross-section perpendicular to the datum axis. Total runout controls surface variation across the entire surface longitudinally and radially. The indicator reading captures all surface irregularities including eccentricity, ovality, and lobing.

Derivation

TIR is the simplest runout metric: the difference between the farthest and closest surface points from the datum axis as measured by an indicator at a fixed position while the part rotates.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Mount the part on a precision rotating fixture (e.g., between centers or on a rotary table). Position the dial indicator perpendicular to the surface.

Datum Diameter:50.0000 mm
Speed:300.0000 rpm
Result: Setup complete for runout measurement
Step 2

Rotate the part one full revolution and record the maximum and minimum indicator readings.

Max Reading:0.1200 mm
Min Reading:0.0200 mm
Result: Readings recorded
Step 3

Calculate the runout as TIR and compare to the specified tolerance.

Runout = Max - Min
TIR:0.1000 mm
Tolerance:0.1500 mm
Intermediate: Runout = 0.1200 - 0.0200
Result: Circular Runout: 0.1000 mm → Pass
Final Answer
0.1000

Worked Examples

See how the calculator works with different scenarios.

Scenario

A 50 mm shaft journal is inspected with a dial indicator. Max reading: 0.12 mm, Min reading: 0.02 mm. Tolerance: 0.15 mm.

Inputs

Max Reading:0.12 mm
Min Reading:0.02 mm
Tolerance:0.15 mm

Calculation

TIR = 0.12 - 0.02 = 0.10 mm Deviation Ratio = 0.10 / 0.15 = 0.667

Result

Deviation Ratio: 0.667 → Pass

Interpretation

The shaft journal runout is well within tolerance with 33% margin. This is acceptable for general machinery applications.

Understanding Your Result

Your Result: Total Runout (TIR): 0.1000 mm

Typical range: Typical runout tolerances: 0.005-0.025 mm for precision spindles, 0.025-0.1 mm for machined shafts, 0.1-0.5 mm for general industrial components, 0.5-2.0 mm for fabricated or welded assemblies.

What This Means

Runout quantifies how much a surface deviates from perfect rotation about a datum axis. It is the simplest and most commonly used GD&T control for rotating parts, measured directly with a dial indicator.

Why It Matters

Excessive runout causes vibration, noise, bearing wear, seal leakage, and poor surface finish in machining. It directly affects the performance, lifespan, and safety of rotating machinery.

Professional Interpretation

Runout combines all surface irregularities including concentricity error, ovality, lobing, and surface roughness. The deviation ratio indicates whether the measured part meets the design requirement. A ratio > 1.0 indicates rejection.

Recommendations

  • •Zero the indicator before each measurement sequence
  • •Measure at multiple positions along the shaft length for total runout
  • •Use a precision rotary table or between-centers setup for accurate results
  • •Account for indicator tip deflection and cosine error
  • •Perform runout measurement at operating temperature for thermally sensitive parts
  • •Document indicator position and orientation relative to the surface

Educational Content

Introduction

Runout is a GD&T tolerance that controls the surface variation of a feature as it rotates 360° about a datum axis. It is the primary control for rotating parts and is simple to measure with standard shop-floor equipment.

Concept Explanation

A dial indicator is positioned perpendicular to the surface. As the part rotates, the indicator measures the variation in distance from the surface to the datum axis. The total range (TIR/FIM) is the runout value. Circular runout measures one cross-section; total runout measures the entire surface.

Applications

▸Rotating shafts and spindles
▸Brake rotors and drums
▸Gear and pulley mounting surfaces
▸Motor and generator armatures
▸Turbine and compressor rotors
▸Wheel and tire assemblies
▸Seal mating surfaces

Benefits

  • •Simple and quick to measure with standard indicator
  • •Low measurement cost and setup time
  • •Combines eccentricity, form, and surface variation into one metric
  • •Directly indicates functional quality for rotating parts
  • •Widely understood by machinists and inspectors

Limitations

  • •Does not distinguish between different error sources (eccentricity vs. ovality vs. lobing)
  • •Single cross-section measurement may miss localized defects
  • •Sensitive to fixturing and datum axis quality
  • •Requires careful indicator positioning to avoid cosine error
  • •Not suitable for stationary or non-rotating features

Best Practices

  • •Support the part between precision centers for shaft runout
  • •Use a V-block setup for large or heavy parts
  • •Apply light, consistent indicator contact pressure
  • •Measure at multiple angular positions and cross-sections
  • •Record both circular and total runout where applicable
  • •Use electronic indicators with data output for SPC

Common Misconceptions

Myth: Runout only measures eccentricity.
Truth: Runout measures all surface variations including eccentricity, ovality, lobing, and surface imperfections. It is a composite measurement.
Myth: Circular runout and total runout are the same.
Truth: Circular runout measures one cross-section. Total runout measures the entire surface in both the radial and axial directions simultaneously.
Myth: Zero runout means the part is perfectly round.
Truth: Zero runout means the surface is coaxial with the rotation axis, but the part could still be out-of-round if the indicator is positioned at a single point.

Practical Tips

  • •Always zero the indicator on the highest point of the surface
  • •Use a ball tip indicator for rough surfaces to avoid tip wear
  • •Take multiple readings at different rotational speeds to verify consistency
  • •For total runout, traverse the indicator along the surface during rotation
  • •Check for spindle or fixture runout before measuring the part
  • •Consider temperature effects — thermal expansion can change runout readings
  • •Use sine bar or angled indicator holder for tapered surface runout

Common Mistakes

Cosine error from non-perpendicular indicator positioning
Ensure the indicator axis is exactly perpendicular to the surface. Use a gage block or square for alignment.
Confusing TIR with actual runout tolerance
TIR is the measured value. Compare TIR to the specified runout tolerance on the drawing, not to an arbitrary limit.
Measuring runout on an unqualified datum
The datum axis must be established from the datum feature per the drawing. Using an incorrect datum invalidates the measurement.
Not accounting for indicator stand stability
Use a magnetic base or rigid stand. Indicator stand deflection can add 0.01-0.05 mm error to readings.

Assumptions

This calculator makes the following assumptions to provide estimates:

Rigid Part: The calculation assumes the part is rigid and does not deflect under its own weight or indicator contact force.
Single Cross-Section: This calculator evaluates circular runout at a single cross-section. Total runout requires longitudinal traversing during rotation.
Smooth Rotation: The part rotates at constant speed with no vibration or wobble from the fixture.
Linear Indicator Response: The dial indicator is assumed to have linear response over the measurement range. Always verify calibration.

Limitations

Be aware of these limitations when using this calculator:

Single Cross-Section Only: This calculator evaluates circular runout at one cross-section. For total runout, traverse the indicator along the surface.
No Error Source Identification: The calculator reports total runout but cannot distinguish between eccentricity, ovality, lobing, or surface roughness contributions.
2D Measurement: Runout as defined here is a 1D measurement (radial variation). Real parts require 3D evaluation for complete surface control.
No Dynamic Effects: The calculation does not account for dynamic effects such as resonance, unbalance, or fluid film effects in operating conditions.

Frequently Asked Questions

Answers to common questions about this calculator.

What is runout in GD&T?
Runout is a geometric tolerance that controls the surface variation of a feature as it rotates 360° about a datum axis. It is measured with a dial indicator as the part rotates.
What is the difference between circular runout and total runout?
Circular runout controls surface variation at a single cross-section. Total runout controls variation across the entire surface longitudinally and radially simultaneously.
What is TIR?
Total Indicator Reading (TIR) is the full range of movement of the dial indicator needle during one complete revolution of the part. TIR equals the runout value.
How is runout measured?
Mount the part on a precision rotating fixture. Position a dial indicator perpendicular to the surface. Rotate the part 360° and record the min and max readings. TIR = max - min.
What is FIM?
Full Indicator Movement (FIM) is synonymous with TIR. Both terms refer to the total deflection range of the dial indicator.
What causes excessive runout?
Common causes include: eccentric mounting, bent shafts, out-of-round features, uneven bearing wear, machining errors, thermal distortion, and assembly misalignment.
How do I convert runout to eccentricity?
Eccentricity is approximately half the TIR if the surface is round and the only error is center offset. Actual runout includes form errors, so this approximation may not be accurate.
What is the runout symbol?
Circular runout: a single arrow (↗). Total runout: two arrows (↗↗) in the feature control frame.
Can runout be measured on stationary parts?
No, runout requires relative rotation between the part and indicator. For stationary parts, use concentricity or position tolerance.
What is the typical runout tolerance for shafts?
General machined shafts: 0.05-0.2 mm. Precision ground shafts: 0.01-0.05 mm. High-speed spindles: 0.002-0.01 mm.
How does bearing runout affect shaft runout?
Bearing internal clearance and raceway runout directly contribute to shaft runout. Precision bearings (ABEC 5/7/9) have specified runout limits.
What is the effect of surface finish on runout?
Surface roughness adds noise to the indicator reading. For accurate runout measurement, surface roughness should be less than 10% of the runout tolerance.
How do I measure runout on a large diameter part?
Use multiple indicators at equally spaced positions and the part rotated incrementally, or use a precision rotary table with the indicator mounted on a rigid stand.
What is the relationship between runout and balance?
Runout causes mass eccentricity in rotating parts. This produces unbalance forces proportional to the runout magnitude and rotational speed squared.
How does runout affect seal performance?
Excessive runout causes lip seal leakage and wear. Most rotary seal manufacturers specify maximum allowable runout for their products (typically 0.05-0.15 mm).
What is the difference between radial and axial runout?
Radial runout measures variation perpendicular to the axis (side-to-side). Axial runout (also called face runout) measures variation parallel to the axis (end-to-end).
Can runout be measured with a laser?
Yes, laser displacement sensors can measure runout without contact. This is preferred for soft surfaces, high-speed applications, or automated inspection.
How do I interpret runout on a CMM report?
CMM reports show the deviation at each measured point and the calculated TIR. Compare the TIR to the specified runout tolerance on the drawing.
What is the minimum measurable runout?
With a precision dial indicator (0.001 mm resolution), minimum measurable runout is approximately 0.002 mm. Laser sensors can measure to 0.0001 mm.
How does speed affect runout measurement?
Higher speeds can introduce centrifugal growth, dynamic runout (different from static), and vibration that mask true runout. Measure at or near operating speed when possible.
What is the runout tolerance for brake rotors?
Typical automotive brake rotor runout: 0.05-0.08 mm (lateral runout). Excessive runout causes brake pulsation.
How do I fix excessive runout?
Solutions: re-machining (turning/grinding between centers), straightening (for shafts), shimming or adjusting mounting, replacing worn bearings, or rebalancing the assembly.
What is the difference between runout and concentricity?
Runout measures surface variation during rotation (includes form errors). Concentricity measures median point location relative to datum axis. Runout is easier to measure.
How does chuck runout affect machined part runout?
Chuck runout is directly transferred to the workpiece. Use precision chucks with runout ≤ 0.01 mm for tight-tolerance work.
What is the effect of temperature on runout?
Thermal expansion can change part geometry during measurement. For precision runout, allow parts to stabilize at 20°C ± 1°C before measurement.
How do I specify runout on a drawing?
Use a feature control frame with the runout symbol (↗ or ↗↗), tolerance value, and datum reference. Example: [↗ | 0.1 | A] for circular runout relative to datum A.
Can runout be applied to internal surfaces?
Yes, runout applies to both external (OD) and internal (ID) surfaces. For internal runout, use a bore gage or inside indicator.
What is the statistical distribution of runout?
Runout data typically follows a Rayleigh or Weibull distribution. Process capability indices should account for the non-normal distribution.
How does runout relate to vibration analysis?
Runout at 1× rotational frequency indicates eccentricity. Higher-order harmonics (2×, 3×, etc.) indicate ovality or lobing. FFT analysis can separate these components.
What is the cost implication of tight runout?
Tight runout tolerances require precision machining, additional inspection time, and potentially grinding operations. Costs increase significantly below 0.025 mm.
How do I choose between circular and total runout?
Use circular runout for single cross-section control. Use total runout when surface variation along the entire length is critical (e.g., seal surfaces, bearing journals).
Can runout be measured on a lathe?
Yes, runout can be measured on the lathe by mounting a dial indicator while the part rotates in the chuck or between centers.

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Glossary

Technical terms used in mortgage calculations explained in plain language.

Axial Runout
Runout measured parallel to the axis of rotation (face runout). Controls end-face variation as the part rotates.
Circular Runout
A GD&T tolerance controlling surface variation at a single cross-section perpendicular to the datum axis during one full rotation.
Cosine Error
Measurement error caused by the indicator axis not being exactly perpendicular to the surface, resulting in readings that are lower than the true value.
Datum Axis
The theoretically exact axis established from a datum feature, serving as the rotation reference for runout measurement.
FIM
Full Indicator Movement — the total range of indicator deflection during one complete revolution. Synonymous with TIR.
Radial Runout
Runout measured perpendicular to the axis of rotation. Controls surface variation in the radial direction.
TIR
Total Indicator Reading — the difference between maximum and minimum indicator readings during one complete revolution.
Total Runout
A GD&T tolerance controlling surface variation across the entire surface simultaneously in both radial and axial directions.
Tolerance Zone
For runout, the annular area between two concentric circles (circular runout) or two coaxial cylinders (total runout).
V-block
A support fixture with a V-shaped groove used to position cylindrical parts for runout measurement.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

ISO 1101ASME Y14.5ISO 2768ASME B89.1.6MISO 4287AGMA 2000

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Page Information

Last Updated:

2026-07-30

Version:

2.0.0

License:

Free to use for educational and professional purposes.