Hole Size Calculator
Calculate the actual hole size range based on nominal size and tolerances. This tool helps engineers determine minimum and maximum hole limits for proper fit, assembly, and manufacturing control.
Hole Size
Calculator
mm
+mm
-mm
Hole Range: 0 - 0 mm
Formula: Min = Nominal + Lower, Max = Nominal + Upper
Quick Answer
- Minimum Hole Size = Nominal + Lower Tolerance
- Maximum Hole Size = Nominal + Upper Tolerance
Core Formula
D_ = D_ + T_
D_ = D_ + T_
👉 Where:
- Dnominal = Nominal hole size (mm)
- Tupper = Upper tolerance (mm)
- Tlower = Lower tolerance (mm)
- Dmin / Dmax = Hole size limits
How to Use
- Enter nominal hole size (mm)
- Enter upper tolerance (+mm)
- Enter lower tolerance (−mm or 0)
- Instantly get:
- Minimum hole size
- Maximum hole size
- Hole tolerance range
✔ Real-time calculation
✔ Supports ISO tolerance system
✔ Ideal for design and inspection
Why Hole Size Calculation Matters
Hole tolerance determines:
✅ Fit & Assembly
- Clearance fit
- Transition fit
- Interference fit
✅ Functional Performance
- Shaft alignment
- Bearing fit
- Load distribution
✅ Manufacturing Control
- Ensures parts meet drawing specs
- Reduces scrap and rework
Example Calculation
Nominal Size: 10 mm
Upper Tolerance: +0.02 mm
Lower Tolerance: 0 mm
D_ = 10 + 0 = 10 mm
D_ = 10 + 0.02 = 10.02 mm
👉 Result: Hole Range = 10.00 – 10.02 mm
Typical Hole Tolerance Examples
| Fit Type | Example Range |
|---|---|
| Clearance Fit | Hole > Shaft |
| Transition Fit | Slight overlap |
| Interference Fit | Hole < Shaft |
Engineering Tips
Designing Hole Tolerance
- Use larger tolerance for non-critical features
- Use tight tolerance for precision fits
Manufacturing Considerations
- Drilling → wider tolerance
- Reaming → tighter tolerance
- Boring → highest precision
Inspection Notes
- Always measure both min and max limits
- Consider temperature and measurement error
Applications
- Shaft-hole fit design
- Bearing installation
- Mechanical assemblies
- CNC machining drawings
FAQ
What is nominal size?
The target dimension specified in engineering drawings.
Why use upper and lower tolerance?
To define acceptable manufacturing variation.
What if lower tolerance is negative?
It reduces the minimum allowable size.
Is this based on ISO standards?
Yes, commonly used with ISO tolerance systems (H7, etc.).
Related Calculators
- Fits & Tolerance Calculator
- Press Fit Calculator
- GD&T Calculator
