Calculate ISO Limits and Fits for Metric Holes and Shafts
Calculate ISO 286 hole and shaft tolerance limits, minimum and maximum diameters, and clearance, transition, or interference fits. Enter a nominal diameter and select tolerance classes such as H7/g6, H7/k6, or H7/p6 to compare metric fit results.
Metric holes and shafts · 1 to 500 mm · tabulated deviations, no interpolation
ISO Limits and Fits Calculator
Select the nominal diameter and ISO tolerance classes.
Hole and Shaft Tolerance Calculator
Calculated from the ISO size interval.
| Feature | Lower dev. (µm) | Upper dev. (µm) | Min size (mm) | Max size (mm) |
|---|---|---|---|---|
| Hole H7 | 0 | +21 | 25.0000 | 25.0210 |
| Shaft g6 | −20 | −7 | 24.9800 | 24.9930 |
Tolerance Zone Diagram
Hole and shaft zones relative to the common nominal zero line. The drawing is schematic, not a scaled picture of the parts.
ISO 286 Tolerance Calculator Method
This iso 286 tolerance calculator looks up ISO 286-2 tolerance deviations by nominal size range and class. It then calculates four limits in a hole and shaft tolerance calculator, without approximating table values from a continuous formula.
- Hole fit calculator: hole lower size = nominal + EI; upper size = nominal + ES.
- Shaft fit calculator: shaft lower size = nominal + ei; upper size = nominal + es.
- Minimum diametral clearance: hole lower size minus shaft upper size.
- Maximum diametral clearance: hole upper size minus shaft lower size.
Deviations are given in µm; 1 µm equals 0.001 mm. Values at the exact upper boundary use the lower nominal-size interval, for example Ø30 mm belongs to over 18 up to 30 mm.
Clearance Fit Calculator, Transition Fit Calculator and Interference Fits
The clearance fit calculator identifies a positive or zero minimum gap. The transition fit calculator identifies a range crossing zero, meaning either clearance or interference may occur at assembly.
Interference fit calculator metric values are shown as negative signed clearances. The corresponding positive interference magnitude is the absolute value of the negative gap. Thermal assembly, press force, contact pressure and stress are outside the scope of this tool.
For metric fits and tolerances, the tolerance designation alone does not establish surface finish, geometric tolerances, roundness or function under load. Check the actual application.
For manufacturing decisions, consult the controlled editions of ISO 286-1 and ISO 286-2 and verify the required tolerance class against the drawing.
Common Metric Fit Examples
These example fit codes give engineers a starting point for drawing interpretation, not a universal process recommendation.
- H7/g6: clearance across the listed diameter range.
- H7/h6: clearance with a possible line-to-line limit.
- H7/k6 and H7/n6: transition fits for common nominal ranges.
- H7/p6: typically an interference fit.
- H8/f7: generally a looser clearance fit than H7/g6 at the same diameter.
The computed classifications are based on the selected size and deviations, rather than an assumed fit name.
ISO Limits and Fits Questions
What is H7 g6 fit?
H7/g6 is a hole-basis clearance fit. For Ø25 mm, an H7 hole is 25.000 to 25.021 mm and a g6 shaft is 24.980 to 24.993 mm, giving 7 to 41 µm of diametral clearance.
What is the difference between clearance, transition and interference?
Clearance has a nonnegative minimum hole-minus-shaft difference. Interference has a nonpositive maximum difference. Transition spans both positive and negative differences. A zero boundary indicates line-to-line contact is possible.
Is a fit tolerance enough to specify a bearing seat?
No. Bearing type, load direction, shaft or housing rotation, temperature, manufacturing conditions and manufacturer fit recommendations must also be checked.
Does ISO H7 apply to all nominal diameters?
The tolerance size changes across ISO diameter intervals. This calculator only supports the tabulated 1 to 500 mm range and its listed classes; it does not extrapolate beyond that range.
Ready to Quote Your CNC Prototype?
Upload your STEP file and get a DFM review + quote within 12 hours.
No tooling cost. Minimum 1 part.
