Fits and Tolerances Calculator
Calculate shaft and hole tolerances, determine maximum/minimum limits, and identify the fit type (clearance, transition, interference) based on ISO tolerance zones. This tool is essential for precision engineering, CNC machining, and assembly design.
Fits and Tolerances
Calculator
Tolerance of Shaft
Tolerance of Hole
Quick Answer
👉 Basic concept:
- Hole Size = Nominal + (EI to ES)
- Shaft Size = Nominal + (ei to es)
👉 Fit type depends on comparison:
- Clearance Fit → Hole always larger than shaft
- Interference Fit → Shaft always larger than hole
- Transition Fit → May be clearance or interference
Formula (Tolerance & Fit Calculation)
Shaft:
- Max Shaft = Nominal + es
- Min Shaft = Nominal + ei
Hole:
- Max Hole = Nominal + ES
- Min Hole = Nominal + EI
Fit Determination:
- Max Clearance = Max Hole − Min Shaft
- Min Clearance = Min Hole − Max Shaft
👉 Interpretation:
- If both > 0 → Clearance Fit
- If both < 0 → Interference Fit
- If mixed → Transition Fit
ISO Fit Examples (Common)
| Fit Type | Example | Description |
|---|---|---|
| Clearance Fit | H7/g6 | Easy assembly, loose fit |
| Transition Fit | H7/k6 | Precise alignment |
| Interference | H7/p6 | Press fit, tight assembly |
How to Use This Calculator
- Enter nominal diameter (mm)
- Select shaft tolerance zone (e.g., g6, h6, k6)
- Select hole tolerance zone (e.g., H7, H8)
- The calculator outputs:
- Upper/lower deviations
- Max/min diameters
- Tolerance center
- Fit type
✔ Based on ISO tolerance system
✔ Ideal for engineering and design
Shaft Tolerance Explanation
- es (upper deviation) → maximum shaft limit
- ei (lower deviation) → minimum shaft limit
👉 Shaft is usually negative deviation in clearance fits.
Hole Tolerance Explanation
- ES (upper deviation) → maximum hole size
- EI (lower deviation) → minimum hole size
👉 Hole basis system (H) is most common:
- EI = 0
- Tolerance zone above nominal
Common Engineering Uses
1. Assembly Design
- Ensure proper fit between mating parts
2. CNC Machining
- Achieve required tolerances and fits
3. Press Fit Design
- Calculate interference for secure assembly
4. Quality Control
- Verify dimensions meet ISO standards
Important Notes
- Based on ISO 286 tolerance system
- Actual fit may be affected by:
- Surface roughness
- Temperature
- Material elasticity
👉 Always validate critical fits with testing.
Related Calculators
Enhance your engineering workflow:
- Hole Size Calculator
- Surface Roughness Calculator
- Press Fit Calculator
- Tolerance Calculator
FAQ
What is a tolerance fit?
It defines how tightly or loosely two parts fit together.
What is the most common fit system?
👉 Hole basis system (H7)
What is clearance fit?
There is always a gap between hole and shaft.
What is interference fit?
The shaft is always larger than the hole.
What is transition fit?
It can result in either slight clearance or interference.
CNC Machining Shops
Need Precision CNC Parts with ISO Fits?
Accurate tolerances ensure perfect assembly and performance.
👉 We offer:
- CNC machining with ISO tolerance control
- Precision fits (H7, H6, g6, etc.)
- Inspection reports and quality assurance
- Fast quoting and global delivery
Upload your drawing today and get a precision manufacturing solution.
