Tolerance / Fit Calculator
Determine shaft and hole tolerances, limits, and fit type (clearance / transition / interference) based on ISO tolerance systems. This tool helps engineers quickly evaluate fit conditions and assembly behavior.
Fits and Tolerances
Calculator
mm
Tolerance of Shaft
Shaft
Upper limit deviation es- µm
Lower limit deviation ei- µm
Maximum shaft diameter- mm
Minimum shaft diameter- mm
Tolerance centre- mm
Tolerance of Hole
Hole
Upper limit deviation ES- µm
Lower limit deviation EI- µm
Maximum hole diameter- mm
Minimum hole diameter- mm
Tolerance centre- mm
Fit Type: -
Enter diameter and select shaft / hole tolerance zones
Quick Answer
- Shaft Limits = Nominal + (es / ei)
- Hole Limits = Nominal + (ES / EI)
- Fit Type depends on clearance between hole and shaft
Core Formulas
Shaft Limits
D_ = D + es
D_ = D + ei
Hole Limits
D_ = D + ES
D_ = D + EI
Clearance / Interference
Clearance_ = D_ – D_
Clearance_ = D_ – D_
How to Use
- Enter Nominal Diameter (mm)
- Select Shaft tolerance zone (e.g., h6, p6, s6)
- Select Hole tolerance zone (e.g., H7, H8)
- Instantly get:
- Shaft max / min size
- Hole max / min size
- Tolerance center
- Fit type (clearance / transition / interference)
✔ Based on ISO 286 standard
✔ Real-time calculation
✔ Engineering-ready output
Fit Type Classification
| Fit Type | Condition | Description |
|---|---|---|
| Clearance Fit | Clearance > 0 | Easy assembly, free movement |
| Transition Fit | Mixed | Tight fit, slight interference |
| Interference Fit | Clearance < 0 | Press fit, no movement |
Example
Nominal Diameter: 50 mm
Hole: H7
Shaft: p6
👉 Typical Result:
- Hole: 50.000 – 50.025 mm
- Shaft: 50.020 – 50.041 mm
Clearance_ = 50.000 – 50.041 = -0.041
👉 Result: Interference Fit
Why Fit Calculation Matters
✅ Assembly Performance
- Determines ease of assembly
- Affects press force or slip fit
✅ Functional Reliability
- Prevents vibration or loosening
- Ensures proper alignment
✅ Manufacturing Control
- Defines machining tolerance
- Reduces scrap and rework
Common Fit Systems
Hole Basis System (Most Common)
- Hole fixed (H7)
- Shaft varies (h6, p6, s6)
Shaft Basis System
- Shaft fixed
- Hole varies
Engineering Tips
Choosing the Right Fit
- Clearance fit → rotating parts
- Transition fit → accurate positioning
- Interference fit → permanent assembly
Machining Considerations
- Tight tolerance → higher cost
- Grinding / honing → better precision
- Reaming improves hole accuracy
Design Guidelines
- Avoid overly tight fits unless required
- Consider thermal expansion
- Factor in surface finish
Applications
- Shaft & bearing fits
- Gear mounting
- Press fit assemblies
- Automotive & aerospace components
FAQ
What is H7 fit?
A standard hole tolerance zone widely used in engineering.
What does h6 mean?
A shaft tolerance zone with zero upper deviation.
How to choose fit type?
Based on function: movement, positioning, or fixation.
Is this ISO standard?
Yes, based on ISO 286 tolerance system.
Related Calculators
- Press Fit Calculator
- Hole Size Calculator
- GD&T Calculator
