CGCADGuide.tools
Free Engineering Utility

ISO 286 Limits & Fits Calculator

Determine limit deviations, tolerance zones, and fit types for shafts and holes. Visualizes standard ISO 286 clearances and interferences dynamically.

ISO 286 Recommended Fits (Standard Presets)

Fits Configuration

Nominal sizes range up to 500mm. Standard tolerance letters and grades are selectable.

Nominal Size (D)
mm
Min: 1mmISO Range: 18 - 30 mmMax: 500mm
Deviation Letter
IT Grade
Deviation Letter
IT Grade

Tolerance Zone Diagram (μm)

Nominal Zero Line (D = 30 mm)Hole H7Shaft g6+210-7-20

Tolerance Deviation Details

Calculated Fit Classification
Clearance Fit (clearance fit)
Max Clearance: 41.0 μmMin Clearance: 7.0 μm

Hole Limits (H7)

Upper Deviation (ES)+21 μm
Lower Deviation (EI)0 μm
Max Limit Size30.0210 mm
Min Limit Size30.0000 mm
Total Tolerance (IT7)21 μm

Shaft Limits (g6)

Upper Deviation (es)-7 μm
Lower Deviation (ei)-20 μm
Max Limit Size29.9930 mm
Min Limit Size29.9800 mm
Total Tolerance (IT6)13 μm

Engineering Limits & Fits Guide

1. Understanding fit Types

Clearance Fit (Clearance fit: The hole is always larger than the shaft. This allows rotational or axial sliding movement between the parts. Common examples include H7/g6, H8/f7.

Transition Fit (Transition fit: The tolerance bands overlap. Depending on the actual manufactured size, the parts might have a clearance or an interference fit. Used for precise locating keys, pulleys, and centering pins. Common examples include H7/js6, H7/k6.

Interference Fit (Interference fit: The shaft is always larger than the hole. The parts must be pressed together using hydraulic pressure or thermal expansion (heat shrinking). Provides a rigid joint without keyways. Common examples include H7/p6, H7/s6.

2. Standard ISO 286 Nomenclature

// Fit Designation: e.g. H7/g6
Capital Letter "H" represents Hole Tolerance.
Lowercase Letter "g" represents Shaft Tolerance.
Number "7" or "6" represents the International Tolerance (IT) Grade.
// IT Grade scale
Lower IT number = Tighter tolerance band (harder to machine, higher cost).
IT5-IT7: Precision machining (grinding, boring).
IT8-IT11: Standard general machining (turning, milling).

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