International Standards

Tolerances for Holes (ISO 286-2)

The importance of holes on CNC machined parts is no less than that of threads. Parts are usually made to assemble with other ones. When it comes to assembly, the standard tolerances below play an important role. In other words, the relationship between the two mating parts can be determined by "fit". Generally speaking, there are three kinds of fits:

1.) transition fitting

A transition fit is known as a slip or push fit for the mating parts. This kind of fit usually requires highly accurate alignment or tolerance between the mating parts. With a transition fit, the mating parts can fit together without excess play or movement in the assembly.

2.) interference fitting

An interference fit is also called a press fit, tight fit, or friction fit. It is usually used for fixing a bearing onto a shaft or into a hole, or a dowel pin into a hole. It may sometimes be used to assemble spare parts into a single unit to reduce raw material and production costs.

Besides, to optimize the performance of fixing a bearing into a hole, a hole finished with a burnishing process can provide a firm and consistent surface quality. You can refer to Sandy Munro's comments on the motor of the Tesla Model S Plaid at 8'28''.

3.) slide fitting

The slide fit is also called a clearance fit or loose mating. Mating parts with a slide fit can slide in and out without any restriction. A grinding process would be helpful to optimize the surface quality on the mating parts to slide freely between each other.

ISO system of limits and fits basic hole system
Upper and Lower limits in micrometer (0.001 mm)
over up
to		 D10 E9 F7 F8 G7 G9 H6 H7 H8 H9 H11 H12 H13 JS7 JS9 K6 K7 M6 M7 N7 N9 P7 P9 R7
- 3 +60
+20		 +39
+14		 +16
+6		 +20
+10		 +12
+2		 +27
+2		 +6
0		 +10
0		 +14
0		 +25
0		 +60
0		 +100
0		 +140
0		 +5
- 5		 +12.5
-12.5		 0
-6		 0
-10		 -2
-8		 -2
-12		 -4
-14		 -4
-29		 -6
-16		 -6
-31		 -10
-20
3 6 +78
+30		 +50
+20		 +22
+10		 +28
+10		 +16
+4		 +34
+4		 +8
0		 +12
0		 +18
0		 +30
0		 +75
0		 +120
0		 +180
0		 +6
-6		 +15 
-15		 +2
-6		 +3
-9		 -1
-9		 0
-12		 -4
-16		 0
-30		 -8
-20		 -12
-42		 -11
-23
6 10 +98
+40		 +61
+25		 +28
+13		 +35
+13		 +20 
+5		 +41
+5		 +9
0		 +15
0		 +22
0		 +36
0		 +90
0		 +150
0		 +220
0		 +7.5 
-7.5		 +18
-18		 +2 
-7		 +5 
-10		 -3
-12		 0
-15		 -4
-19		 0
-36		 -9
-24		 -15
-51		 -13
-28
10 18 +120
+50		 +75
+32		 +34
+16		 +43
+16		 +24
+6		 +49
+6		 +11
0		 +18
0		 +27
0		 +43
0		 +110
0		 +180
0		 +270
0		 +9
-9		 +21.5
-21.5		 +2
-9		 +6
-12		 -4
-15		 0
-18		 -5
-23		 0
-43		 -11
-29		 -18
-61		 -16
-34
18 30 +149
+65		 +92
+40		 +41
+20		 +53
+20		 +28
+7		 +59
+7		 +13
0		 +21
0		 +33
0		 +52
0		 +130
0		 +210
0		 +330
0		 +10.5
-10.5		 +26 
-26		 +2
-11		 +6
-15		 -4
-17		 0
-21		 -7
-28		 0
-52		 -14
-35		 -22
-74		 -20
-41
30 50 +180
+80		 +112
+50		 +50 
+25		 +64 
+25		 +34 
+9		 +71
+9		 +16
0		 +25
0		 +39
0		 +62
0		 +160
0		 +250
0		 +390
0		 +12.5
-12.5		 +31
-31		 +3 
-13		 +7 
-18		 -4
-20		 0
-25		 -8
-33		 0
-62		 -17
-42		 -26
-88		 -25
-50
50 65 +220
+100		 +134
+60		 +60 
+30		 +76 
+30		 +40 
+10		   +19
0		 +30
0		 +46
0		 +74
0		 +190
0		 +300
0		 +460
0		 +15 
-15		 +37
-37		 +4 
-15		 +9 
-21		 -5
-24		 0
-30		 -9
-39		 0
-74		 -21
-51		 -32
-106		 -30
-60
65 80 +220
+100		 +134
+60		 +60 
+30		 +76 
+30		 +40 
+10		   +19
0		 +30
0		 +46
0		 +74
0		 +190
0		 +300
0		 +460
0		 +15 
-15		 +37
-37		 +4 
-15		 +9 
-21		 -5
-24		 0
-30		 -9
-39		 0
-74		 -21
-51		 -32
-106		 -32
-62
80 100 +260
+120		 +159
+72		 +71 
+36		 +90 
+36		 +47 
+12		   +22
0		 +35
0		 +54
0		 +87
0		 +220
0		 +350
0		 +540
0		 +17.5 
-17.5		 +43.5
-43.5		 +4 
-18		 +10 
-25		 -6
-28		 0
-35		 -10
-45		 0
-87		 -24
-59		 -37
-124		 -38
-73
100 120 +260
+120		 +159
+72		 +71 
+36		 +90 
+36		 +47 
+12		   +22
0		 +35
0		 +54
0		 +87
0		 +220
0		 +350
0		 +540
0		 +17.5 
-17.5		 +43.5
-43.5		 +4 
-18		 +10 
-25		 -6
-28		 0
-35		 -10
-45		 0
-87		 -24
-59		 -37
-124		 -41
-76
120 140 +305
+145		 +185
+85		 +83
+43		 +106
+43		 +54
+14		   +25
0		 +40
0		 +63
0		 +100
0		 +250
0		 +400
0		 +630
0		 +20
-20		 +50
-50		 +4
-21		 +12
-28		 -8
-33		 0
-40		 -12
-52		 0
-100		 -28
-68		 -43
-143		 -48
-88
140 160 +305
+145		 +185
+85		 +83
+43		 +106
+43		 +54
+14		   +25
0		 +40
0		 +63
0		 +100
0		 +250
0		 +400
0		 +630
0		 +20
-20		 +50
-50		 +4
-21		 +12
-28		 -8
-33		 0
-40		 -12
-52		 0
-100		 -28
-68		 -43
-143		 -50
-90
160 180 +305
+145		 +185
+85		 +83
+43		 +106
+43		 +54
+14		   +25
0		 +40
0		 +63
0		 +100
0		 +250
0		 +400
0		 +630
0		 +20
-20		 +50
-50		 +4
-21		 +12
-28		 -8
-33		 0
-40		 -12
-52		 0
-100		 -28
-68		 -43
-143		 -53
-93
180 200 +335
+170		 +215
+110		 +96
+50		 +122
+50		 +61
+15		   +29
0		 +46
0		 +72
0		 +115
0		 +290
0		 +460
0		 +720
0		 +23
-23		 +57.5
-57.5		 +5
-24		 +13
-33		 -8
-37		 0
-46		 -14
-60		 0
-115		 -33
-79		 -50
-165		 -60
-106
200 225 +335
+170		 +215
+110		 +96
+50		 +122
+50		 +61
+15		   +29
0		 +46
0		 +72
0		 +115
0		 +290
0		 +460
0		 +720
0		 +23
-23		 +57.5
-57.5		 +5
-24		 +13
-33		 -8
-37		 0
-46		 -14
-60		 0
-115		 -33
-79		 -50
-165		 -63
-109
225 250 +335
+170		 +215
+110		 +96
+50		 +122
+50		 +61
+15		   +29
0		 +46
0		 +72
0		 +115
0		 +290
0		 +460
0		 +720
0		 +23
-23		 +57.5
-57.5		 +5
-24		 +13
-33		 -8
-37		 0
-46		 -14
-60		 0
-115		 -33
-79		 -50
-165		 -67
-113
250 280 +400
+190		 +240
+110		 +108
+56		 +137
+56		 +69
+17		   +32
0		 +52
0		 +81
0		 +130
0		 +320
0		 +520
0		 +810
0		 +26
-26		 +65
-65		 +5
-27		 +16
-36		 -9
-41		 0
-52		 -14
-66		 0
-130		 -36
-88		 -56
-186		 -74
-126
280 315 +400
+190		 +240
+110		 +108
+56		 +137
+56		 +69
+17		   +32
0		 +52
0		 +81
0		 +130
0		 +320
0		 +520
0		 +810
0		 +26
-26		 +65
-65		 +5
-27		 +16
-36		 -9
-41		 0
-52		 -14
-66		 0
-130		 -36
-88		 -56
-186		 -78
-130
315 355 +440
+210		 +265
+125		 +119
+62		 +151
+62		 +75
+18		   +36
0		 +57
0		 +89
0		 +140
0		 +360
0		 +570
0		 +890
0		 +28.5
-28.5		 +70
-70		 +7
-29		 +17
-40		 -10
-46		 0
-57		 -16
-73		 0
-140		 -41
-98		 -62
-202		 -87
-144
355 400 +440
+210		 +265
+125		 +119
+62		 +151
+62		 +75
+18		   +36
0		 +57
0		 +89
0		 +140
0		 +360
0		 +570
0		 +890
0		 +28.5
-28.5		 +70
-70		 +7
-29		 +17
-40		 -10
-46		 0
-57		 -16
-73		 0
-140		 -41
-98		 -62
-202		 -93
-150

Tolerances for Shafts (ISO 286-2)

ISO system of limits and fits basic shaft system

Upper and Lower limits in micrometer (0.001 mm)
over

up

to

 d9 e8 f7 g6 h5 h6 h7 h8 h9 h11 js5 js6 js13 js14 k5 k6 m5 m6 n5 n6 p6 r6 s6 s7

-

3

 -20
-45		 -14
-28		 -6
-16		 -2
-8		 0
-4		 0
-6		 0
-10		 0
-14		 0
-25		 0
-60		 +2
-2		 +3
-3		 +70
-70		 +125
-125		 +40
0		 +60
0		 +6
+2		 +8
+2		 +8
+4		 +10
+4		 +12
+6		 +16
+10		 +20
+14		 +24
+14
3 6 -30
-60		 -20
-38		 -10
-22		 -4
-12		 0
-5		 0
-8		 0
-12		 0
-18		 0
-30		 0
-75		 +2.5
-2.5		 +4
-4		 +90
-90		 +150
-150		 +6
+1		 +9
+1		 +9
+4		 +12
+4		 +13
+8		 +16
+8		 +20
+12		 +23
+15		 +27
+19		 +31
+19
6 10 -40
-76		 -25
-47		 -13
-28		 -5
-14		 0
-6		 0
-9		 0
-15		 0
-22		 0
-36		 0
-90		 +3
-3		 +4.5
-4.5		 +110
-110		 +180
-180		 +7
+1		 +10
+1		 +12
+6		 +15
+6		 +16
+10		 +19
+10		 +24
+15		 +28
+19		 +32
+23		 +38
+23
10 18 -50
-93		 -32
-59		 -16
-34		 -6
-17		 0
-8		 0
-11		 0
-18		 0
-27		 0
-43		 0
-110		 +4
-4		 +5.5
-5.5		 +135
-135		 +215
-215		 +9
+1		 +12
+1		 +15
+7		 +18
+7		 +20
+12		 +23
+12		 +29
+18		 +34
+23		 +39
+28		 +46
+28
18 30 -65
-117		 -40
-73		 -20
-41		 -7
-20		 0
-9		 0
-13		 0
-21		 0
-33		 0
-52		 0
-130		 +4.5
-4.5		 +6.5
-6.5		 +165
-165		 +260
-260		 +11
+2		 +15
+2		 +17
+8		 +21
+8		 +24
+15		 +28
+15		 +35
+22		 +41
+28		 +48
+35		 +56
+35
30 50 -80
-142		 -50
-89		 -25
-50		 -9
-25		 0
-11		 0
-16		 0
-25		 0
-39		 0
-62		 0
-160		 +5.5
-5.5		 +8
-8		 +195
-195		 +310
-310		 +13
+2		 +18
+2		 +20
+9		 +25
+9		 +28
+17		 +33
+17		 +42
+26		 +50
+34		 +59
+43		 +68
+43
50 65 -100
-174		 -60
-106		 -30
-60		 -10
-29		 0
-13		 0
-19		 0
-30		 0
-46		 0
-74		 0
-190		 +6.5
-6.5		 +9.5
-9.5		 +230
-230		 +370
-370		 +15
+2		 +21
+2		 +24
+11		 +30
+11		 +33
+20		 +39
+20		 +51
+32		 +60
+41		 +72
+53		 +83
+53
65 80 -100
-174		 -60
-106		 -30
-60		 -10
-29		 0
-13		 0
-19		 0
-30		 0
-46		 0
-74		 0
-190		 +6.5
-6.5		 +9.5
-9.5		 +230
-230		 +370
-370		 +15
+2		 +21
+2		 +24
+11		 +30
+11		 +33
+20		 +39
+20		 +51
+32		 +62
+43		 +78
+59		 +89
+59
80 100 -120
-207		 -72
-126		 -36
-71		 -12
-34		 0
-15		 0
-22		 0
-35		 0
-54		 0
-87		 0
-220		 +7.5
-7.5		 +11
-11		 +270
-270		 +435
-435		 +18
+3		 +25
+3		 +28
+13		 +35
+13		 +38
+23		 +45
+23		 +59
+37		 +73
+51		 +93
+71		 +106
+71
100 120 -120
-207		 -72
-126		 -36
-71		 -12
-34		 0
-15		 0
-22		 0
-35		 0
-54		 0
-87		 0
-220		 +7.5
-7.5		 +11
-11		 +270
-270		 +435
-435		 +18
+3		 +25
+3		 +28
+13		 +35
+13		 +38
+23		 +45
+23		 +59
+37		 +76
+54		 +101
+79		 +114
+79
120 140 -145
-245		 -85
-148		 -43
-83		 -14
-39		 0
-18		 0
-25		 0
-40		 0
-63		 0
-100		 0
-250		 +9
-9		 +12.5
-12.5		 +315
-315		 +500
-500		 +21
+3		 +28
+3		 +33
+15		 +40
+15		 +45
+27		 +52
+27		 +68
+43		 +88
+63		 +117
+92		 +132
+92
140 160 -145
-245		 -85
-148		 -43
-83		 -14
-39		 0
-18		 0
-25		 0
-40		 0
-63		 0
-100		 0
-250		 +9
-9		 +12.5
-12.5		 +315
-315		 +500
-500		 +21
+3		 +28
+3		 +33
+15		 +40
+15		 +45
+27		 +52
+27		 +68
+43		 +90
+65		 +125
+100		 +140
+100
160 180 -145
-245		 -85
-148		 -43
-83		 -14
-39		 0
-18		 0
-25		 0
-40		 0
-63		 0
-100		 0
-250		 +9
-9		 +12.5
-12.5		 +315
-315		 +500
-500		 +21
+3		 +28
+3		 +33
+15		 +40
+15		 +45
+27		 +52
+27		 +68
+43		 +93
+68		 +133
+108		 +148
+108
180 200 -170
-285		 -100
-172		 -50
-96		 -15
-44		 0
-20		 0
-29		 0
-46		 0
-72		 0
-115		 0
-290		 +10
-10		 +14.5
-14.5		 +360
-360		 +575
-575		 +24
+4		 +33
+4		 +37
+17		 +46
+17		 +51
+31		 +60
+31		 +79
+50		 +106
+77		 +151
+122		 +168
+122
200 225 -170
-285		 -100
-172		 -50
-96		 -15
-44		 0
-20		 0
-29		 0
-46		 0
-72		 0
-115		 0
-290		 +10
-10		 +14.5
-14.5		 +360
-360		 +575
-575		 +24
+4		 +33
+4		 +37
+17		 +46
+17		 +51
+31		 +60
+31		 +79
+50		 +109
+80		 +159
+130		 +176
+130
225 250 -170
-285		 -100
-172		 -50
-96		 -15
-44		 0
-20		 0
-29		 0
-46		 0
-72		 0
-115		 0
-290		 +10
-10		 +14.5
-14.5		 +360
-360		 +575
-575		 +24
+4		 +33
+4		 +37
+17		 +46
+17		 +51
+31		 +60
+31		 +79
+50		 +113
+84		 +169
+140		 +186
+140
250 280 -190
-320		 -110
-191		 -56
-108		 -17
-49		 0
-23		 0
-32		 0
-52		 0
-81		 0
-130		 0
-320		 +11.5
-11.5		 +16
-16		 +405
-405		 +650
-650		 +27
+4		 +36
+4		 +43
+20		 +52
+20		 +57
+34		 +66
+34		 +88
+56		 +126
+94		 +190
+158		 +210
+158
280 315 -190
-320		 -110
-191		 -56
-108		 -17
-49		 0
-23		 0
-32		 0
-52		 0
-81		 0
-130		 0
-320		 +11.5
-11.5		 +16
-16		 +405
-405		 +650
-650		 +27
+4		 +36
+4		 +43
+20		 +52
+20		 +57
+34		 +66
+34		 +88
+56		 +130
+98		 +202
+170		 +222
+170
315 355 -210
-350		 -125
-214		 -62
-119		 -18
-54		 0
-25		 0
-36		 0
-57		 0
-89		 0
-140		 0
-360		 +12.5
-12.5		 +18
-18		 +445
-445		 +700
-700		 +29
+4		 +40
+4		 +46
+21		 +57
+21		 +62
+37		 +73
+37		 +98
+62		 +144
+108		 +226
+190		 +247
+190
355 400 -210
-350		 -125
-214		 -62
-119		 -18
-54		 0
-25		 0
-36		 0
-57		 0
-89		 0
-140		 0
-360		 +12.5
-12.5		 +18
-18		 +445
-445		 +700
-700		 +29
+4		 +40
+4		 +46
+21		 +57
+21		 +62
+37		 +73
+37		 +98
+62		 +150
+114		 +244
+208		 +265
+208

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