Formula
- Tolerance unit i = 0.45 × ³√D + 0.001D (µm)
- IT grade = multiplier × i (IT6=10, IT7=16, IT8=25, IT9=40)
- Hole H: EI=0, ES=+IT
- Shaft: es from letter, ei = es − IT
About this calculator
Part of our GD&T & Metrology Calculators collection. True position, fits, ISO tolerances, and surface roughness.
How it works
Select nominal size and standard hole and shaft classes such as H7/g6. The calculator returns limit dimensions and resulting clearance range. Use this for a quick fit check before detailed drawing tolerancing.
Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.
Worked example
50 mm nominal, H7 hole and g6 shaft.
- IT7 ≈ 27 µm → hole 50.000 to 50.027 mm
- g6 shaft es ≈ −9 µm, IT6 ≈ 18 µm → shaft 49.974 to 49.991 mm
- Clearance 0.009 to 0.054 mm
Result: Clearance fit H7/g6 at 50 mm.
When to use
- Selecting standard ISO fits from hole and shaft classes
- Quick limit dimension check before detailed drawing
- Teaching or verifying H7/g6, H7/h6, and similar combinations
Limitations
- Simplified fundamental deviation formulas; use tables for certification
- Limited to H holes and common shaft letters (g, f, h, k, n, p, s)
- Nominal size should be in standard ISO diameter range (0.1 to 500 mm)
FAQ
- What was fixed in this calculator?
- Tolerance values were previously treated as millimetres instead of micrometres. The calculator now uses ISO tolerance unit i and letter deviations correctly.
- What is H7/g6?
- A common clearance fit: H7 hole with IT7 tolerance, g6 shaft with g deviation and IT6 grade. Typical for sliding fits on 30–50 mm parts.
Privacy and accuracy
Every calculation runs locally in your browser. Your design data never leaves your device. Results are intended for preliminary engineering work. Always verify critical designs with qualified review and applicable standards before production use.
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