ISO Hole and Shaft tolerances/limits

Relevant Standards

BS EN 20286-1:1993(ISO 286-1:1988 )...... ISO system of limits and fits. Bases of tolerances, deviations and fits
BS EN 20286-2 : 1993(ISO 286-2:1988 ).... ISO system of limits and fits. Tables of standard tolerance grades and limit deviations for holes and shafts


The tolerance of size is normally defined as the difference between the upper and lower dimensions.

The need for tolerances to be identified on drawings is vital to allow assembly of parts in the desired way and interchangeability of parts as required in modern manufacturing methods.

ISO 286 implements 20 grades of accuracy to satisfy the requirements of different industries.

Hole and Shaft tolerance tables- Using Fundamental Deviations and Tolerance Band T

ISO Tolerance Band T
(3-315mm size)
ISO Shaft limit nearest Zero
(3-500mm shaft size)
ISO Hole Nearest limit nearest Zero
(0-500mm hole size)
ISO Tolerance Band T
(315-3150mm size)
ISO Shaft limit nearest Zero
(500-3150mm shaft size)
ISO Hole Nearest limit nearest Zero
(500-3150mm hole size)

Examples in using above tables..

Note: The tolerance band T is an absolute length value it does not have a negative value.

Hole Dia 110mm H11,...
Nearest zero ( El )= 110mm + 0mm = 110,000mm ...
Furthest from zero ( ES )= 110mm + (0+ T=0,220)=110,220mm
Resulting limits 110,000/110,220

Shaft 110mm e9...
Nearest zero ( es ) = 110mm - 0,072=109,928mm...
Furthest from zero ( ei ) = 110mm - (0,072 + T=0,087) = 109,841mm
Resulting limits 109,928/109,841

Note for the tolerance bands which can be either side of zero, (J,K,N,j )
The diagrams provided with the table clearly show calculation needed.e.g. consider Hole 300K7.

T= 52 micrometres (0,052mm). Limit nearest zero ( K ) ES = 16 micrometres = (0,016mm)
Limit furthest from zero ( K ) El = (0,016- 0,052)= -0,036
Limits therefore (300 -0,036) = 299,964..and ...300+0,016= 300,016
limits 299,964/300,016

Hole and Shaft Tolerances to ISO 286-2
ISO Hole Limits (3-400mm Hole Size) ISO Shaft Tolerance(3-400mm Hole Size)
ISO Hole Limits (400-3150mm Hole Size) ISO Shaft Tolerance(400-3150 mm Hole Size)

Example limits and fits using hole basis
DescriptionHole Shaft
Loose RunningH11 c11
Free RunningH9 d9
Loose RunningH11 c11
Easy Running - Good quality easy to do-H8 f8
SlidingH7 g6
Close Clearance - Spigots and locationsH8 f7
Location/ClearanceH7 h6
Location- slight interferenceH7 k6
Location/TransitionH7 n6
Location/Interference- Press fit which can be separatedH7p6
Medium DriveH7 s6
ForceH7 u6

Machining Process associated with ISO IT Tolerance Grade..
IT Grade 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Cylinderical grinding                              
Diamond turning                              
Plan grinding                              
Boring, Turning                              
Planing, Shaping                              
Cold Rolling, Drawing                              
Die Casting                              
Sand Casting                              
Hot rolling, Flame cutting                              

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