Calculator Inputs
Enter nominal size in millimeters. Enter deviations and target fit window in micrometers.
Example Data Table
| Nominal Size (mm) | Hole Limits (mm) | Shaft Limits (mm) | Minimum Clearance (mm) | Maximum Clearance (mm) | Measured Fit (mm) | Result |
|---|---|---|---|---|---|---|
| 50.000 | 49.995 to 50.012 | 50.000 to 50.010 | -0.015 | 0.012 | 0.002 | Transition fit with measured clearance |
| 25.000 | 24.998 to 25.006 | 25.001 to 25.007 | -0.009 | 0.005 | -0.003 | Transition fit with measured interference |
| 10.000 | 9.999 to 10.004 | 10.000 to 10.003 | -0.004 | 0.004 | 0.000 | Line-to-line outcome within overlap band |
Formula Used
- Hole minimum size = Nominal size + Hole lower deviation ÷ 1000
- Hole maximum size = Nominal size + Hole upper deviation ÷ 1000
- Shaft minimum size = Nominal size + Shaft lower deviation ÷ 1000
- Shaft maximum size = Nominal size + Shaft upper deviation ÷ 1000
- Minimum clearance = Hole minimum size − Shaft maximum size
- Maximum clearance = Hole maximum size − Shaft minimum size
- Minimum interference = Shaft minimum size − Hole maximum size
- Maximum interference = Shaft maximum size − Hole minimum size
- Allowance = Hole minimum size − Shaft maximum size
- Fit variation = Hole tolerance + Shaft tolerance
A transition fit exists when the hole and shaft tolerance zones overlap, allowing either a small clearance or a small interference after assembly.
How to Use This Calculator
- Enter the nominal size of the mating parts in millimeters.
- Enter lower and upper deviations for the hole and shaft in micrometers.
- Add measured hole and shaft values if you want inspection verification.
- Optionally enter a target fit window to compare the measured assembly result.
- Press Calculate Transition Fit to show the summary above the form.
- Use the CSV or PDF buttons to export the calculated inspection summary.
FAQs
1. What is a transition fit?
It is a fit where tolerance zones overlap. Depending on actual manufactured sizes, assembly may produce slight clearance or slight interference.
2. Why is transition fit useful in quality control?
It helps inspectors judge whether measured hole and shaft values stay within limits while still delivering the intended assembly behavior.
3. What units does this calculator use?
Nominal and measured part sizes use millimeters. Deviations and target fit window values use micrometers for practical shop-floor tolerance work.
4. What does allowance mean here?
Allowance is the difference between the smallest permitted hole and the largest permitted shaft. It indicates the tightest assembly condition.
5. How is actual fit determined?
The calculator subtracts measured shaft size from measured hole size. A positive value means clearance, a negative value means interference.
6. What if measured parts are outside specification?
The conformance line will flag failure when the measured hole or shaft falls outside its calculated limit range.
7. Can I use this for exportable inspection records?
Yes. After calculation, you can download a CSV summary or a PDF summary for reporting, review, or traceability.
8. Does this calculator replace official fit standards?
No. It supports fast evaluation and documentation, but final acceptance should still follow your drawing, standard, and process control plan.