Free Engineering Tool
Shaft-Hole Fit Calculator
Calculate tolerance limits and fit type for shaft-hole combinations per ISO 286. Select nominal dimension, hole tolerance, and shaft tolerance to get clearance or interference values.
This calculator was developed and verified by the Vibromera engineering team, makers of the Balanset portable balancing instruments.
Results
ISO 286 Tolerance System
ISO 286 defines a system of limits and fits for mating parts. Each tolerance specification consists of:
- Fundamental deviation — a letter (H, h, g, k, p, etc.) that sets the position of the tolerance zone relative to the nominal dimension
- IT grade — a number (5, 6, 7, etc.) that defines the width of the tolerance zone
Hole-Basis System
In the hole-basis system (most common), the hole has a fundamental deviation of H (EI = 0), and the shaft letter is varied to achieve the desired fit. This simplifies manufacturing since the hole is harder to adjust.
H holes: The lower deviation EI = 0 for all H holes. The upper deviation ES = EI + IT = IT (the tolerance grade width). So a H7 hole with nominal Ø50 has limits of 50.000 to 50.025 mm.
Fit Classification
| Fit Type | Condition | Typical Combinations |
|---|---|---|
| Clearance | Shaft always smaller than hole | H7/f6, H7/g6, H7/h6 |
| Transition | May be clearance or interference | H7/js6, H7/k6, H7/m6, H7/n6 |
| Interference | Shaft always larger than hole | H7/p6, H7/r6, H7/s6 |
Common Applications
| Fit | Description | Application |
|---|---|---|
| H7/f7 | Free running | Bearings, long shafts, high-speed rotation |
| H7/g6 | Close running | Precision bearings, slideways |
| H7/h6 | Sliding | Pistons, spigots, locating fits |
| H7/k6 | Transition | Keyed shafts, bearing inner rings |
| H7/n6 | Light interference | Press fits for light loads |
| H7/p6 | Press fit | Bearing bushings, permanent assembly |
| H7/s6 | Heavy press | Permanent coupling, shrink fits |
Practical Example
Nominal: 50 mm (range 30–50)
Hole H7: EI = 0 μm, ES = +25 μm → 50.000 to 50.025 mm
Shaft h6: es = 0 μm, ei = −16 μm → 49.984 to 50.000 mm
Max clearance: 50.025 − 49.984 = 0.041 mm
Min clearance: 50.000 − 50.000 = 0.000 mm
Fit type: Clearance (sliding fit)
⚠️ Note: This calculator covers common tolerance combinations for the hole-basis system. For shaft-basis systems or less common tolerance designations, consult the full ISO 286 standard. Values are based on ISO 286-1:2010 tables.
Professional field balancing instruments and software. Precision measurement for shaft and rotor assemblies. Used in 50+ countries.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
