ISO Tolerance Chart: H7, h6, g6 Limits and Fits (ISO 286)

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Reviewed by MLC Editorial Team | 2 October 2026

Close-up shot of a vintage camera with ISO chart, emphasizing its classic design. — Photo by Dithira Hettiarachchi on Pexels

ISO 286 limit deviations for holes and shafts from 0 to 500 mm, with the common H7-based fit classes and what each is for. In the hole-basis system the hole is held to one tolerance (H7 is the standard) and the shaft tolerance is changed to set the fit: a clearance fit for sliding, a transition fit for accurate location, or an interference fit for a permanent press. H7/g6 slides freely and H7/p6 is a press fit. An H7 hole between 18 and 30 mm is +21 / 0 micrometres, and between 30 and 50 mm it is +25 / 0. The fit selection guide covers choosing between them.

Fit (hole/shaft)	Type	Typical use
H7/g6	Clearance (sliding)	Precise location with free movement - spigots, guide bushes, sliding parts
H7/h6	Clearance (location/slip)	Easy hand assembly, accurate location - gears and pulleys on shafts
H7/k6	Transition	Accurate location with slight grip, removable with a mallet - couplings, pulleys
H7/n6	Transition (tight)	Accurate location needing light press - bushes, gears for heavier duty
H7/p6	Interference (press)	Permanent location pressed together - bushes into housings, dowels
H7/s6	Interference (shrink)	High-load permanent fit, often shrink-fitted - rings and collars on shafts
H11/c11	Coarse clearance	Loose running fit for rough work - pivots, agricultural linkages

ISO 286 limits and fit calculator

Nominal size (mm)

Hole

Shaft

Hole: --

Shaft: --

How to read an ISO fit

A fit is written as hole tolerance over shaft tolerance, for example H7/g6. The capital letter is the hole, the lower-case letter is the shaft. The number is the tolerance grade (IT grade) - a smaller number is a tighter band. For a given diameter range the standard gives the exact upper and lower limits in micrometres.

Hole tolerance chart: H6 to H11 and clearance classes

Upper and lower deviation in micrometres, written upper / lower. Add them to the nominal size to get the limits: a 40 mm H7 hole is 40.000 to 40.025 mm.

Diameter (mm)	H6	H7	H8	H9	H11	G7	F8	E9	D10
Up to 3	+6 / 0	+10 / 0	+14 / 0	+25 / 0	+60 / 0	+12 / +2	+20 / +6	+39 / +14	+60 / +20
Over 3 to 6	+8 / 0	+12 / 0	+18 / 0	+30 / 0	+75 / 0	+16 / +4	+28 / +10	+50 / +20	+78 / +30
Over 6 to 10	+9 / 0	+15 / 0	+22 / 0	+36 / 0	+90 / 0	+20 / +5	+35 / +13	+61 / +25	+98 / +40
Over 10 to 18	+11 / 0	+18 / 0	+27 / 0	+43 / 0	+110 / 0	+24 / +6	+43 / +16	+75 / +32	+120 / +50
Over 18 to 30	+13 / 0	+21 / 0	+33 / 0	+52 / 0	+130 / 0	+28 / +7	+53 / +20	+92 / +40	+149 / +65
Over 30 to 50	+16 / 0	+25 / 0	+39 / 0	+62 / 0	+160 / 0	+34 / +9	+64 / +25	+112 / +50	+180 / +80
Over 50 to 80	+19 / 0	+30 / 0	+46 / 0	+74 / 0	+190 / 0	+40 / +10	+76 / +30	+134 / +60	+220 / +100
Over 80 to 120	+22 / 0	+35 / 0	+54 / 0	+87 / 0	+220 / 0	+47 / +12	+90 / +36	+159 / +72	+260 / +120
Over 120 to 180	+25 / 0	+40 / 0	+63 / 0	+100 / 0	+250 / 0	+54 / +14	+106 / +43	+185 / +85	+305 / +145
Over 180 to 250	+29 / 0	+46 / 0	+72 / 0	+115 / 0	+290 / 0	+61 / +15	+122 / +50	+215 / +100	+355 / +170
Over 250 to 315	+32 / 0	+52 / 0	+81 / 0	+130 / 0	+320 / 0	+69 / +17	+137 / +56	+240 / +110	+400 / +190
Over 315 to 400	+36 / 0	+57 / 0	+89 / 0	+140 / 0	+360 / 0	+75 / +18	+151 / +62	+265 / +125	+440 / +210
Over 400 to 500	+40 / 0	+63 / 0	+97 / 0	+155 / 0	-	+83 / +20	+165 / +68	+290 / +135	-

Hole tolerance chart: transition and interference classes

Diameter (mm)	JS7	K7	M7	N7	P7
Up to 3	+5 / -5	0 / -10	-2 / -12	-4 / -14	-6 / -16
Over 3 to 6	+6 / -6	+3 / -9	0 / -12	-4 / -16	-8 / -20
Over 6 to 10	+7.5 / -7.5	+5 / -10	0 / -15	-4 / -19	-9 / -24
Over 10 to 18	+9 / -9	+6 / -12	0 / -18	-5 / -23	-11 / -29
Over 18 to 30	+10.5 / -10.5	+6 / -15	0 / -21	-7 / -28	-14 / -35
Over 30 to 50	+12.5 / -12.5	+7 / -18	0 / -25	-8 / -33	-17 / -42
Over 50 to 80	+15 / -15	+9 / -21	0 / -30	-9 / -39	-21 / -51
Over 80 to 120	+17.5 / -17.5	+10 / -25	0 / -35	-10 / -45	-24 / -59
Over 120 to 180	+20 / -20	+12 / -28	0 / -40	-12 / -52	-28 / -68
Over 180 to 250	+23 / -23	+13 / -33	0 / -46	-14 / -60	-33 / -79
Over 250 to 315	+26 / -26	+16 / -36	0 / -52	-14 / -66	-36 / -88
Over 315 to 400	+28.5 / -28.5	+17 / -40	0 / -57	-16 / -73	-41 / -98
Over 400 to 500	+31.5 / -31.5	+18 / -45	0 / -63	-17 / -80	-45 / -108

R7 and S7 are tabulated in narrower size steps above 50 mm:

Diameter (mm)	R7	S7
Up to 3	-10 / -20	-14 / -24
Over 3 to 6	-11 / -23	-15 / -27
Over 6 to 10	-13 / -28	-17 / -32
Over 10 to 18	-16 / -34	-21 / -39
Over 18 to 30	-20 / -41	-27 / -48
Over 30 to 50	-25 / -50	-34 / -59
Over 50 to 65	-30 / -60	-42 / -72
Over 65 to 80	-32 / -62	-48 / -78
Over 80 to 100	-38 / -73	-58 / -93
Over 100 to 120	-41 / -76	-66 / -101
Over 120 to 140	-48 / -88	-77 / -117
Over 140 to 160	-50 / -90	-85 / -125
Over 160 to 180	-53 / -93	-93 / -133
Over 180 to 200	-60 / -106	-105 / -151
Over 200 to 225	-63 / -109	-113 / -159
Over 225 to 250	-67 / -113	-123 / -169
Over 250 to 280	-74 / -126	-
Over 280 to 315	-78 / -130	-
Over 315 to 355	-87 / -144	-
Over 355 to 400	-93 / -150	-
Over 400 to 450	-103 / -166	-
Over 450 to 500	-109 / -172	-

Shaft tolerance chart: h5 to h11 and clearance classes

A 20 mm h6 shaft is 0 / -13 micrometres, so 19.987 to 20.000 mm.

Diameter (mm)	h5	h6	h7	h9	h11	g6	f7	e8	d9
Up to 3	0 / -4	0 / -6	0 / -10	0 / -25	0 / -60	-2 / -8	-6 / -16	-14 / -28	-20 / -45
Over 3 to 6	0 / -5	0 / -8	0 / -12	0 / -30	0 / -75	-4 / -12	-10 / -22	-20 / -38	-30 / -60
Over 6 to 10	0 / -6	0 / -9	0 / -15	0 / -36	0 / -90	-5 / -14	-13 / -28	-25 / -47	-40 / -76
Over 10 to 18	0 / -8	0 / -11	0 / -18	0 / -43	0 / -110	-6 / -17	-16 / -34	-32 / -59	-50 / -93
Over 18 to 30	0 / -9	0 / -13	0 / -21	0 / -52	0 / -130	-7 / -20	-20 / -41	-40 / -73	-65 / -117
Over 30 to 50	0 / -11	0 / -16	0 / -25	0 / -62	0 / -160	-9 / -25	-25 / -50	-50 / -89	-80 / -142
Over 50 to 80	0 / -13	0 / -19	0 / -30	0 / -74	0 / -190	-10 / -29	-30 / -60	-60 / -106	-100 / -174
Over 80 to 120	0 / -15	0 / -22	0 / -35	0 / -87	0 / -220	-12 / -34	-36 / -71	-72 / -126	-120 / -207
Over 120 to 180	0 / -18	0 / -25	0 / -40	0 / -100	0 / -250	-14 / -39	-43 / -83	-85 / -148	-145 / -245
Over 180 to 250	0 / -20	0 / -29	0 / -46	0 / -115	0 / -290	-15 / -44	-50 / -96	-100 / -172	-170 / -285
Over 250 to 315	0 / -23	0 / -32	0 / -52	0 / -130	0 / -320	-17 / -49	-56 / -108	-110 / -191	-190 / -320
Over 315 to 400	0 / -25	0 / -36	0 / -57	0 / -140	0 / -360	-18 / -54	-62 / -119	-125 / -214	-210 / -350
Over 400 to 500	0 / -27	0 / -40	0 / -63	0 / -155	0 / -400	-20 / -60	-68 / -131	-135 / -232	-230 / -385

Shaft tolerance chart: transition and interference classes

Diameter (mm)	js6	k6	m6	n6	p6
Up to 3	+3 / -3	+6 / 0	+8 / +2	+10 / +4	+12 / +6
Over 3 to 6	+4 / -4	+9 / +1	+12 / +4	+16 / +8	+20 / +12
Over 6 to 10	+4.5 / -4.5	+10 / +1	+15 / +6	+19 / +10	+24 / +15
Over 10 to 18	+5.5 / -5.5	+12 / +1	+18 / +7	+23 / +12	+29 / +18
Over 18 to 30	+6.5 / -6.5	+15 / +2	+21 / +8	+28 / +15	+35 / +22
Over 30 to 50	+8 / -8	+18 / +2	+25 / +9	+33 / +17	+42 / +26
Over 50 to 80	+9.5 / -9.5	+21 / +2	+30 / +11	+39 / +20	+51 / +32
Over 80 to 120	+11 / -11	+25 / +3	+35 / +13	+45 / +23	+59 / +37
Over 120 to 180	+12.5 / -12.5	+28 / +3	+40 / +15	+52 / +27	+68 / +43
Over 180 to 250	+14.5 / -14.5	+33 / +4	+46 / +17	+60 / +31	+79 / +50
Over 250 to 315	+16 / -16	+36 / +4	+52 / +20	+66 / +34	+88 / +56
Over 315 to 400	+18 / -18	+40 / +4	+57 / +21	+73 / +37	+98 / +62
Over 400 to 500	+20 / -20	+45 / +5	+63 / +23	+80 / +40	+108 / +68

r6 and s6 are tabulated in narrower size steps above 50 mm:

Diameter (mm)	r6	s6
Up to 3	+16 / +10	+20 / +14
Over 3 to 6	+23 / +15	+27 / +19
Over 6 to 10	+28 / +19	+32 / +23
Over 10 to 18	+34 / +23	+39 / +28
Over 18 to 24	+41 / +28	+48 / +35
Over 24 to 30	+41 / +28	+48 / +35
Over 30 to 50	+50 / +34	+59 / +43
Over 50 to 65	+60 / +41	+72 / +53
Over 65 to 80	+62 / +43	+78 / +59
Over 80 to 100	+73 / +51	+93 / +71
Over 100 to 120	+76 / +54	+101 / +79
Over 120 to 140	+88 / +63	+117 / +92
Over 140 to 160	+90 / +65	+125 / +100
Over 160 to 180	+93 / +68	+133 / +108
Over 180 to 200	+106 / +77	+151 / +122
Over 200 to 225	+109 / +80	+159 / +130
Over 225 to 250	+113 / +84	+169 / +140
Over 250 to 280	+126 / +94	+190 / +158
Over 280 to 315	+130 / +98	+202 / +170
Over 315 to 355	+144 / +108	+226 / +190
Over 355 to 400	+150 / +114	+244 / +208
Over 400 to 450	+166 / +126	-
Over 450 to 500	+172 / +132	-

IT grades: the width of each tolerance band

The number in a tolerance class is its IT grade, and the grade sets the width of the band in micrometres for each size range. The letter then sets where that band sits relative to nominal. Every class in the charts above obeys this: the upper deviation minus the lower deviation equals the IT value below.

Diameter (mm)	IT5	IT6	IT7	IT8	IT9	IT10	IT11	IT12
Up to 3	4	6	10	14	25	40	60	100
Over 3 to 6	5	8	12	18	30	48	75	120
Over 6 to 10	6	9	15	22	36	58	90	150
Over 10 to 18	8	11	18	27	43	70	110	180
Over 18 to 30	9	13	21	33	52	84	130	210
Over 30 to 50	11	16	25	39	62	100	160	250
Over 50 to 80	13	19	30	46	74	120	190	300
Over 80 to 120	15	22	35	54	87	140	220	350
Over 120 to 180	18	25	40	63	100	160	250	400
Over 180 to 250	20	29	46	72	115	185	290	460
Over 250 to 315	23	32	52	81	130	210	320	520
Over 315 to 400	25	36	57	89	140	230	360	570
Over 400 to 500	27	40	63	97	155	250	400	630

Worked example: 25 mm H7/g6

For a 25 mm shaft in an H7/g6 sliding fit, the hole is 25.000 to 25.021 mm and the shaft is 24.980 to 24.993 mm, giving a guaranteed clearance of 7 to 41 micrometres. Tolerances widen with diameter, so always read the band for the actual size range.

Related standards

ISO 286-1 - System of limits and fits, bases of tolerances
ISO 286-2 - Tables of standard tolerance grades and limit deviations
BS EN ISO 286 - UK implementation

References

ISO 286-1:2010 - Limits and fits - bases of tolerances
ISO 286-2:2010 - Tables of tolerance grades and deviations

Related reference pages: keyway dimensions chart.

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Frequently Asked Questions

What is an H7 tolerance?

H7 is the standard hole tolerance in the ISO 286 hole-basis system. The lower limit is the nominal size (zero deviation) and the upper limit is positive, so an H7 hole is always at or above nominal. For an 18 to 30 mm diameter, H7 is +0.021/0 mm, meaning a 25 mm H7 hole measures 25.000 to 25.021 mm.

What is the difference between H7/g6 and H7/p6?

H7/g6 is a clearance (sliding) fit - the shaft is always smaller than the hole, so parts slide or rotate freely, used for guide bushes and spigots. H7/p6 is an interference (press) fit - the shaft is larger than the hole, so the parts must be pressed together for a permanent joint, used for bushes in housings.

What does the number in a fit like H7 mean?

The number is the IT (International Tolerance) grade, which sets the width of the tolerance band. A smaller number is a tighter, more precise tolerance. IT6 and IT7 are typical for machined shafts and holes; IT11 is a coarse grade for rough fits. The band width also grows with the part diameter.

What is the H7 tolerance for a 35 mm hole?

For diameters over 30 mm up to 50 mm, H7 is +25 / 0 micrometres, so a 35 mm H7 hole is 35.000 to 35.025 mm.

What is the h6 tolerance for a 20 mm shaft?

For diameters over 18 mm up to 30 mm, h6 is 0 / -13 micrometres, so a 20 mm h6 shaft is 19.987 to 20.000 mm.

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