Preferred fits

Construction Fundamentals

Preferred fits

The table below shows the preferred fits according to ANSI B4.2-1978 with its overlap with the preferred fits of ISO 286-1 (2010) marked in green. Fits on shaft basis are preferred because of the availability of h6 dowel pins. For precision mechanisms G7/h6 is generally used as H7/h6 has a risk of getting stuck when parts are very clean or have surface defects. Regarding the depth of dowel pins in parts, for transition and interference fits a depth of 2x to 3x the nominal pin diameter is recommended. For a clearance fit lower depth is recommended to reduce the risk of the pin getting stuck: 1x to 2x the nominal pin diameter. For interference fits, a transition from a clearance fit to an interference fit can be used to guide the shaft into the hole, e.g. a hole that changes from G7 to P7 (in combination with a h6 shaft) to end up with a P7/h6 interference fit.

Preferred fits low depth
 ISO symbol*Description
Hole basisShaft basis
Clearance fitsH11/c11C11/h11Loose running fit for wide commercial tolerances or allowances on external members.More clearance
H9/d9D9/h9 D10/h6Free running fit not for use where accuracy is essential, but good for large temperature variations, high running speeds, or heavy journal pressures.
H8/f7F8/h7 F7/h6Close running fit for running on accurate machines and for accurate location at moderate speeds and journal pressures.
H7/g6G7/h6Sliding fit not intended to run freely, but to move and turn freely and locate accurately.
H7/h6H7/h6Locational clearance fit provides snug fit for locating stationary parts; but can be freely assembled and disassembled.
Transition fitsH7/k6K7/h6Locational transition fit for accurate location, a compromise between clearance and interference. Effective joining by means of hand-held hammer.
H7/n6N7/h6Locational transition fit for more accurate location where greater interference is permissible. Joining achievable by means of press.
Interference fitsH7/p6P7/h6Locational interference fit for parts requiring rigidity and alignment with prime accuracy of location but without special bore pressure requirements.
H7/s6S7/h6Medium drive fit for ordinary steel parts or shrink fits on light sections, the tightest fit usable with cast iron.
H7/u6U7/h6Force fit suitable for parts which can be highly stressed or for shrink fits where the heavy pressing forces required are impractical.More interference

*Green: preferred fits according to ISO 286-1 (2010) & ANSI B4.2-1978, Black: preferred fits according to ANSI B4.2-1978, Blue: alternative fits based on h6 shafts.

Hole tolerances for preferred fits up to 400 mm

Nominal hole sizes (mm)Tolerance class symbol (tolerances in μm)
AboveUp to and includingC11D9D10F7F8G7H7H8H9H11K7N7P7S7U7
03+120
+60
+45
+20
+60
+20
+16
+6
+20
+6
+12
+2
+10
0
+14
0
+25
0
+60
0
0
-10
-4
-14
-6
-12
-14
-24
-18
-28
36+145
+70
+60
+30
+78
+30
+22
+10
+28
+10
+16
+4
+12
0
+18
0
+30
0
+75
0
+3
-9
-4
-16
-8
-20
-15
-27
-19
-31
610+170
+80
+76
+40
+98
+40
+28
+13
+35
+13
+20
+5
+15
0
+22
0
+36
0
+90
0
+5
-10
-4
-19
-9
-24
-17
-32
-22
-37
1018+205
+95
+93
+50
+120
+50
+34
+16
+43
+16
+24
+6
+18
0
+27
0
+43
0
+110
0
+6
-12
-5
-23
-11
-29
-21
-39
-26
-44
1824+240
+110
+117
+65
+149
+65
+41
+20
+53
+20
+28
+7
+21
0
+33
0
+52
0
+130
0
+6
-15
-7
-28
-14
-35
-27
-48
-33
-54
2430+240
+110
+117
+65
+149
+65
+41
+20
+53
+20
+28
+7
+21
0
+33
0
+52
0
+130
0
+6
-15
-7
-28
-14
-35
-27
-48
-40
-61
3040+280
+120
+142
+80
+180
+80
+50
+25
+64
+25
+34
+9
+25
0
+39
0
+62
0
+160
0
+7
-18
-8
-33
-17
-42
-34
-59
-51
-76
4050+290
+130
+142
+80
+180
+80
+50
+25
+64
+25
+34
+9
+25
0
+39
0
+62
0
+160
0
+7
-18
-8
-33
-17
-42
-34
-59
-61
-86
5065+330
+140
+174
+100
+220
+100
+60
+30
+76
+30
+40
+10
+30
0
+46
0
+74
0
+190
0
+9
-21
-9
-39
-21
-51
-42
-72
-76
-106
6580+340
+150
+174
+100
+220
+100
+60
+30
+76
+30
+40
+10
+30
0
+46
0
+74
0
+190
0
+9
-21
-9
-39
-21
-51
-48
-78
-91
-121
80100+390
+170
+207
+120
+260
+120
+71
+36
+90
+36
+47
+12
+35
0
+54
0
+87
0
+220
0
+10
-25
-10
-45
-24
-59
-58
-93
-111
-146
100120+400
+180
+207
+120
+260
+120
+71
+36
+90
+36
+47
+12
+35
0
+54
0
+87
0
+220
0
+10
-25
-10
-45
-24
-59
-66
-101
-131
-166
120140+450
+200
+245
+145
+305
+145
+83
+43
+106
+43
+54
+14
+40
0
+63
0
+100
0
+250
0
+12
-28
-12
-52
-28
-68
-77
-117
-155
-195
140160+460
+210
+245
+145
+305
+145
+83
+43
+106
+43
+54
+14
+40
0
+63
0
+100
0
+250
0
+12
-28
-12
-52
-28
-68
-85
-125
-175
-215
160180+480
+230
+245
+145
+305
+145
+83
+43
+106
+43
+54
+14
+40
0
+63
0
+100
0
+250
0
+12
-28
-12
-52
-28
-68
-93
-133
-195
-235
180200+530
+240
+285
+170
+355
+170
+96
+50
+122
+50
+61
+15
+46
0
+72
0
+115
0
+290
0
+13
-33
-14
-60
-33
-79
-105
-151
-219
-265
200225+550
+260
+285
+170
+355
+170
+96
+50
+122
+50
+61
+15
+46
0
+72
0
+115
0
+290
0
+13
-33
-14
-60
-33
-79
-113
-159
-241
-287
225250+570
+280
+285
+170
+355
+170
+96
+50
+122
+50
+61
+15
+46
0
+72
0
+115
0
+290
0
+13
-33
-14
-60
-33
-79
-123
-169
-267
-313
250280+620
+300
+320
+190
+400
+190
+108
+56
+137
+56
+69
+17
+52
0
+81
0
+130
0
+320
0
+16
-36
-14
-66
-36
-88
-138
-190
-295
-347
280315+650
+330
+320
+190
+400
+190
+108
+56
+137
+56
+69
+17
+52
0
+81
0
+130
0
+320
0
+16
-36
-14
-66
-36
-88
-150
-202
-330
-382
315355+720
+360
+350
+210
+440
+210
+119
+62
+151
+62
+75
+18
+57
0
+89
0
+140
0
+360
0
+17
-40
-16
-73
-41
-98
-169
-226
-369
-426
355400+760
+400
+350
+210
+440
+210
+119
+62
+151
+62
+75
+18
+57
0
+89
0
+140
0
+360
0
+17
-40
-16
-73
-41
-98
-187
-244
-414
-471

Shaft tolerances for preferred fits up to 400 mm

Nominal shaft sizes (mm)Tolerance class symbol (tolerances in μm)
AboveUp to and includingc11d9f7g6h6h7h9h11k6n6p6s6u6
03-60
-120
-20
-45
-6
-16
-2
-8
0
-6
0
-10
0
-25
0
-60
+6
0
+10
+4
+12
+6
+20
+14
+24
+18
36-70
-145
-30
-60
-10
-22
-4
-12
0
-8
0
-12
0
-30
0
-75
+9
+1
+16
+8
+20
+12
+27
+19
+31
+23
610-80
-170
-40
-76
-13
-28
-5
-14
0
-9
0
-15
0
-36
0
-90
+10
+1
+19
+10
+24
+15
+32
+23
+37
+28
1018-95
-205
-50
-93
-16
-34
-6
-17
0
-11
0
-18
0
-43
0
-110
+12
+1
+23
+12
+29
+18
+39
+28
+44
+33
1824-110
-240
-65
-117
-20
-41
-7
-20
0
-13
0
-21
0
-52
0
-130
+15
+2
+28
+15
+35
+22
+48
+35
+54
+41
2430-110
-240
-65
-117
-20
-41
-7
-20
0
-13
0
-21
0
-52
0
-130
+15
+2
+28
+15
+35
+22
+48
+35
+61
+48
3040-120
-280
-80
-142
-25
-50
-9
-25
0
-16
0
-25
0
-62
0
-160
+18
+2
+33
+17
+42
+26
+59
+43
+76
+60
4050-130
-290
-80
-142
-25
-50
-9
-25
0
-16
0
-25
0
-62
0
-160
+18
+2
+33
+17
+42
+26
+59
+43
+86
+70
5065-140
-330
-100
-174
-30
-60
-10
-29
0
-19
0
-30
0
-74
0
-190
+21
+2
+39
+20
+51
+32
+72
+53
+106
+87
6580-150
-340
-100
-174
-30
-60
-10
-29
0
-19
0
-30
0
-74
0
-190
+21
+2
+39
+20
+51
+32
+78
+59
+121
+102
80100-170
-390
-120
-207
-36
-71
-12
-34
0
-22
0
-35
0
-87
0
-220
+25
+3
+45
+23
+59
+37
+93
+71
+146
+124
100120-180
-400
-120
-207
-36
-71
-12
-34
0
-22
0
-35
0
-87
0
-220
+25
+3
+45
+23
+59
+37
+101
+79
+166
+144
120140-200
-450
-145
-245
-43
-83
-14
-39
0
-25
0
-40
0
-100
0
-250
+28
+3
+52
+27
+68
+43
+117
+92
+195
+170
140160-210
-460
-145
-245
-43
-83
-14
-39
0
-25
0
-40
0
-100
0
-250
+28
+3
+52
+27
+68
+43
+125
+100
+215
+190
160180-230
-480
-145
-245
-43
-83
-14
-39
0
-25
0
-40
0
-100
0
-250
+28
+3
+52
+27
+68
+43
+133
+108
+235
+210
180200-240
-530
-170
-285
-50
-96
-15
-44
0
-29
0
-46
0
-115
0
-290
+33
+4
+60
+31
+79
+50
+151
+122
+265
+236
200225-260
-550
-170
-285
-50
-96
-15
-44
0
-29
0
-46
0
-115
0
-290
+33
+4
+60
+31
+79
+50
+159
+130
+287
+258
225250-280
-570
-170
-285
-50
-96
-15
-44
0
-29
0
-46
0
-115
0
-290
+33
+4
+60
+31
+79
+50
+169
+140
+313
+284
250280-300
-620
-190
-320
-56
-108
-17
-49
0
-32
0
-52
0
-130
0
-320
+36
+4
+66
+34
+88
+56
+190
+158
+347
+315
280315-330
-650
-190
-320
-56
-108
-17
-49
0
-32
0
-52
0
-130
0
-320
+36
+4
+66
+34
+88
+56
+202
+170
+382
+350
315355-360
-720
-210
-350
-62
-119
-18
-54
0
-36
0
-57
0
-140
0
-360
+40
+4
+73
+37
+98
+62
+226
+190
+426
+390
355400-400
-760
-210
-350
-62
-119
-18
-54
0
-36
0
-57
0
-140
0
-360
+40
+4
+73
+37
+98
+62
+244
+208
+471
+435

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