H7/h6 is a common sliding fit combination per ISO 286. H7 is a hole with fundamental deviation H (lower limit = nominal) and IT grade 7. h6 is a shaft with fundamental deviation h (upper limit = nominal) and IT grade 6. This combination always produces a clearance fit, suitable for sliding or locational fits.

What is the difference between clearance and interference fit?

In a clearance fit, the shaft is always smaller than the hole, leaving a gap. In an interference fit, the shaft is always larger than the hole, requiring force or heat to assemble. A transition fit may result in either slight clearance or slight interference depending on actual manufactured dimensions.

How do I read ISO 286 notation?

ISO 286 notation uses a letter + number format. Uppercase letters (H, G, F...) denote holes; lowercase (h, g, f...) denote shafts. The letter defines the fundamental deviation (position of tolerance zone), and the number is the IT grade (tolerance width). Example: H7/g6 means hole H grade 7 with shaft g grade 6.

What are common shaft-hole fit combinations?

Common combinations include: H7/h6 (sliding fit), H7/g6 (close running fit), H7/f7 (free running fit), H7/k6 (transition/location fit), H7/n6 (tight transition fit), H7/p6 (light press fit), H7/s6 (heavy press fit). The hole-basis system (H hole) is most commonly used.

IT (International Tolerance) grade defines the magnitude of the tolerance zone. Lower IT numbers mean tighter tolerances: IT5 and IT6 are for precision fits, IT7 is for general engineering, IT8–IT9 for semi-precision, IT11 for rough work. Each step roughly multiplies tolerance by 1.6×.

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.

ISO 286 IT5 – IT11 Hole-Basis System

Nominal Dimension (mm range)

Hole Tolerance

Shaft Tolerance

Quick presets

Results

Fit Type

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Hole Max (ES)

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Hole Min (EI)

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Shaft Max (es)

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Shaft Min (ei)

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Max Clearance / Min Interference

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Min Clearance / Max Interference

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Tolerance Zone Diagram

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: Lower limit = Nominal + EI, Upper limit = Nominal + ES

Shaft: Upper limit = Nominal + es, Lower limit = Nominal + ei

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

Example — Ø50 H7/h6

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.

Shaft-Hole Fit Calculator | ISO 286 | Tolerance & Clearance

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026