Calculator Inputs
Example Data Table
This table shows typical input cases. Values are examples only.
| Nominal Size | Fit | Hole EI | Hole ES | Shaft ei | Shaft es | Expected Result |
|---|---|---|---|---|---|---|
| 50 mm | H7/g6 | 0 µm | 25 µm | -25 µm | -9 µm | Sliding clearance |
| 50 mm | H7/h6 | 0 µm | 25 µm | -16 µm | 0 µm | Close clearance |
| 50 mm | H7/k6 | 0 µm | 25 µm | 2 µm | 18 µm | Transition fit |
| 50 mm | H7/p6 | 0 µm | 25 µm | 26 µm | 42 µm | Press fit |
Formula Used
Minimum hole = nominal size + hole lower deviation.
Maximum hole = nominal size + hole upper deviation.
Minimum shaft = nominal size + shaft lower deviation.
Maximum shaft = nominal size + shaft upper deviation.
Minimum clearance = minimum hole − maximum shaft.
Maximum clearance = maximum hole − minimum shaft.
Allowance = minimum hole − maximum shaft.
Thermal change = nominal size × expansion coefficient × 10-6 × temperature difference.
Combined uncertainty = √(hole uncertainty² + shaft uncertainty²).
Cp = tolerance width ÷ 6σ.
How to Use This Calculator
- Enter the nominal hole and shaft size.
- Select millimeters or inches for the nominal size.
- Choose a common fit preset or enter custom deviations.
- Enter hole and shaft deviations using the selected deviation unit.
- Add coating, plating, or finish allowance when needed.
- Add temperature data for operating condition checks.
- Enter measurement uncertainty for guarded clearance results.
- Press the calculate button and review the result above the form.
- Download the report as CSV or PDF.
Article: Understanding Hole and Shaft Tolerance
Why Fits Matter
A mechanical fit controls how two parts assemble. The hole is the internal feature. The shaft is the external feature. Both parts use limits around a nominal size. These limits define the real manufacturing window. A good fit reduces rejects. It also improves motion, alignment, sealing, and service life.
Clearance, Transition, and Interference
A clearance fit always leaves space between the parts. It is common for sliding, rotating, and removable assemblies. An interference fit always creates overlap. It is used for press assemblies, strong location, and torque transfer. A transition fit can give either result. It depends on the actual produced sizes.
Using Deviations
Deviations show how far each limit sits from the nominal size. Hole deviations use EI and ES. Shaft deviations use ei and es. The lower deviation creates the minimum limit. The upper deviation creates the maximum limit. The tolerance is the distance between those two limits.
Advanced Checks
Real assemblies may change after machining. Temperature can expand or shrink parts. Coatings can reduce bore size or increase shaft size. Measurement uncertainty can hide risk near zero clearance. This calculator includes those effects. It also gives Cp values when process sigma is known.
Good Practice
Use presets for early design work. Use custom deviations for final drawings. Compare guarded clearance values before approving tight fits. Check the process capability when tolerances are narrow. Confirm critical dimensions with calibrated tools. For production release, verify all limits against the official standard and your shop requirements.
FAQs
1. What is a hole and shaft tolerance?
It is the allowed size variation for mating internal and external features. It defines minimum and maximum limits for each part.
2. What is a clearance fit?
A clearance fit means the smallest hole is still larger than the largest shaft. The parts can assemble without forced pressure.
3. What is an interference fit?
An interference fit means the shaft is larger than the hole in all limit conditions. Pressing, heating, or cooling may be required.
4. What is a transition fit?
A transition fit may produce clearance or interference. The final result depends on the actual manufactured hole and shaft sizes.
5. What does allowance mean?
Allowance is the difference between the minimum hole and maximum shaft. Positive allowance indicates clearance. Negative allowance indicates interference.
6. Why include temperature correction?
Parts expand or contract with temperature. A fit that works at inspection temperature may change under operating conditions.
7. How does coating affect the fit?
Internal coating reduces hole diameter. External coating increases shaft diameter. Both changes can reduce clearance or increase interference.
8. Are the presets official standard values?
The presets are practical approximations for quick checks. Enter exact table deviations when creating production drawings or inspection plans.