What is the tolerance for a 25 mm H7 hole?

A 25 mm H7 hole runs 25.000 to 25.021 mm — 0 to +21 µm, because IT7 at that size band is 21 µm wide and H means the band starts at the nominal size.

What does the IT number in a tolerance like H7 or g6 mean?

It is the ISO 286 standard tolerance grade, and it sets how wide the band is for that nominal size. The grades in this chart run IT5 to IT12, each roughly 1.6× the width of the one before, and every one widens as the nominal size grows.

How do I read a fundamental deviation table?

The letter fixes the deviation nearest the nominal size — the position of the band — and the grade fixes its width. Capital letters are holes, lowercase are shafts. H and h are the zero-deviation cases: an H hole is never smaller than nominal and an h shaft is never larger.

Which nominal sizes does this chart cover?

The IT grade table covers the full ISO 286 range from 0 to 500 mm in 13 size bands. The per-designation and per-fit tables cover the 13 nominal sizes with verified demand: 5 mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 80 mm, 100 mm.

Chart · ISO 286

ISO 286 Tolerance Chart — IT Grades, Deviations and Fits

https://shopmath.org/charts/iso-tolerances · data verified August 1, 2026

A Ø25 mm H7 hole is 25.000 to 25.021 mm — 0 to +21 µm, an IT7 band 21 µm wide. Three complete ISO 286 tables: standard tolerance grades across 13 size bands, 24 hole and shaft designations at 13 nominal sizes, and the clearance of 16 standard fits. Every value is compiled from the published ISO 286-2 tables.

Grades: 8
Size bands: 13
Designations: 24
Fits: 16
Verified: August 1, 2026

Most looked-up row · H7 hole at Ø25 mm · deviation, µm

+21 / 0

Max Ø: 25.021mm
Min Ø: 25.000mm
IT7 band: 21µm

At 20 °C. Full 25 mm H7 tolerance page →

ISO 286 Standard Tolerance Grades (IT Grades) by Size Band

The width of the tolerance band for each grade, in micrometres, across the whole ISO 286 size range. The letter in a designation says where the band sits; this table says how wide it is.

ISO 286 standard tolerance grades IT5 to IT12, by nominal size band, in micrometres
Property	Standard tolerance, µm
Nominal size, mm	IT5	IT6	IT7	IT8	IT9	IT10	IT11	IT12
over 0 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

Bands are open at the bottom and closed at the top: 'over 18 to 30' includes 30 mm and excludes 18 mm. Values are compiled from the ISO 286-1 table, not evaluated from the standard tolerance factor — the formula deviates from the published table by up to 13%.

ISO 286 Hole and Shaft Deviations by Designation and Nominal Size

Upper and lower deviation for every designation in this reference, at each verified nominal size, in micrometres. Cells link to the full page for that size where one exists.

ISO 286 upper and lower deviations by designation and nominal diameter, in micrometres
Property	Property	Upper / lower deviation by nominal Ø, µm
Designation	Applies to	5	6	8	10	12	16	20	25	30	40	50	80	100
c11	shaft	-70/-145	-70/-145	-80/-170	-80/-170	-95/-205	-95/-205	-110/-240	-110/-240	-110/-240	-120/-280	-130/-290	-150/-340	-170/-390
d9	shaft	-30/-60	-30/-60	-40/-76	-40/-76	-50/-93	-50/-93	-65/-117	-65/-117	-65/-117	-80/-142	-80/-142	-100/-174	-120/-207
e8	shaft	-20/-38	-20/-38	-25/-47	-25/-47	-32/-59	-32/-59	-40/-73	-40/-73	-40/-73	-50/-89	-50/-89	-60/-106	-72/-126
f7	shaft	-10/-22	-10/-22	-13/-28	-13/-28	-16/-34	-16/-34	-20/-41	-20/-41	-20/-41	-25/-50	-25/-50	-30/-60	-36/-71
g6	shaft	-4/-12	-4/-12	-5/-14	-5/-14	-6/-17	-6/-17	-7/-20	-7/-20	-7/-20	-9/-25	-9/-25	-10/-29	-12/-34
h11	shaft	0/-75	0/-75	0/-90	0/-90	0/-110	0/-110	0/-130	0/-130	0/-130	0/-160	0/-160	0/-190	0/-220
h6	shaft	0/-8	0/-8	0/-9	0/-9	0/-11	0/-11	0/-13	0/-13	0/-13	0/-16	0/-16	0/-19	0/-22
h7	shaft	0/-12	0/-12	0/-15	0/-15	0/-18	0/-18	0/-21	0/-21	0/-21	0/-25	0/-25	0/-30	0/-35
h9	shaft	0/-30	0/-30	0/-36	0/-36	0/-43	0/-43	0/-52	0/-52	0/-52	0/-62	0/-62	0/-74	0/-87
k6	shaft	+9/+1	+9/+1	+10/+1	+10/+1	+12/+1	+12/+1	+15/+2	+15/+2	+15/+2	+18/+2	+18/+2	+21/+2	+25/+3
m6	shaft	+12/+4	+12/+4	+15/+6	+15/+6	+18/+7	+18/+7	+21/+8	+21/+8	+21/+8	+25/+9	+25/+9	+30/+11	+35/+13
n6	shaft	+16/+8	+16/+8	+19/+10	+19/+10	+23/+12	+23/+12	+28/+15	+28/+15	+28/+15	+33/+17	+33/+17	+39/+20	+45/+23
p6	shaft	+20/+12	+20/+12	+24/+15	+24/+15	+29/+18	+29/+18	+35/+22	+35/+22	+35/+22	+42/+26	+42/+26	+51/+32	+59/+37
r6	shaft	+23/+15	+23/+15	+28/+19	+28/+19	+34/+23	+34/+23	+41/+28	+41/+28	+41/+28	+50/+34	+50/+34	+62/+43	+73/+51
F8	hole	+28/+10	+28/+10	+35/+13	+35/+13	+43/+16	+43/+16	+53/+20	+53/+20	+53/+20	+64/+25	+64/+25	+76/+30	+90/+36
G7	hole	+16/+4	+16/+4	+20/+5	+20/+5	+24/+6	+24/+6	+28/+7	+28/+7	+28/+7	+34/+9	+34/+9	+40/+10	+47/+12
H11	hole	+75/0	+75/0	+90/0	+90/0	+110/0	+110/0	+130/0	+130/0	+130/0	+160/0	+160/0	+190/0	+220/0
H6	hole	+8/0	+8/0	+9/0	+9/0	+11/0	+11/0	+13/0	+13/0	+13/0	+16/0	+16/0	+19/0	+22/0
H7	hole	+12/0	+12/0	+15/0	+15/0	+18/0	+18/0	+21/0	+21/0	+21/0	+25/0	+25/0	+30/0	+35/0
H8	hole	+18/0	+18/0	+22/0	+22/0	+27/0	+27/0	+33/0	+33/0	+33/0	+39/0	+39/0	+46/0	+54/0
H9	hole	+30/0	+30/0	+36/0	+36/0	+43/0	+43/0	+52/0	+52/0	+52/0	+62/0	+62/0	+74/0	+87/0
K7	hole	+3/-9	+3/-9	+5/-10	+5/-10	+6/-12	+6/-12	+6/-15	+6/-15	+6/-15	+7/-18	+7/-18	+9/-21	+10/-25
N7	hole	-4/-16	-4/-16	-4/-19	-4/-19	-5/-23	-5/-23	-7/-28	-7/-28	-7/-28	-8/-33	-8/-33	-9/-39	-10/-45
P7	hole	-8/-20	-8/-20	-9/-24	-9/-24	-11/-29	-11/-29	-14/-35	-14/-35	-14/-35	-17/-42	-17/-42	-21/-51	-24/-59

Each cell is upper/lower deviation relative to the nominal size. Add them to the nominal size to get the limits — every designation page carries the limits in millimetres.

Clearance of Every Standard ISO 286 Fit by Nominal Size

Minimum and maximum clearance for all sixteen standard fits, in micrometres. Negative is interference — the shaft is larger than the hole.

Minimum and maximum clearance for the standard ISO 286 fits, by nominal diameter, in micrometres
Property	Property	Min / max clearance by nominal Ø, µm
Fit	Type	5	6	8	10	12	16	20	25	30	40	50	80	100
H7/h6	clearance	0/+20	0/+20	0/+24	0/+24	0/+29	0/+29	0/+34	0/+34	0/+34	0/+41	0/+41	0/+49	0/+57
H11/c11	clearance	+70/+220	+70/+220	+80/+260	+80/+260	+95/+315	+95/+315	+110/+370	+110/+370	+110/+370	+120/+440	+130/+450	+150/+530	+170/+610
H7/g6	clearance	+4/+24	+4/+24	+5/+29	+5/+29	+6/+35	+6/+35	+7/+41	+7/+41	+7/+41	+9/+50	+9/+50	+10/+59	+12/+69
H8/e8	clearance	+20/+56	+20/+56	+25/+69	+25/+69	+32/+86	+32/+86	+40/+106	+40/+106	+40/+106	+50/+128	+50/+128	+60/+152	+72/+180
H8/f7	clearance	+10/+40	+10/+40	+13/+50	+13/+50	+16/+61	+16/+61	+20/+74	+20/+74	+20/+74	+25/+89	+25/+89	+30/+106	+36/+125
H9/d9	clearance	+30/+90	+30/+90	+40/+112	+40/+112	+50/+136	+50/+136	+65/+169	+65/+169	+65/+169	+80/+204	+80/+204	+100/+248	+120/+294
H7/p6	interference	-20/0	-20/0	-24/0	-24/0	-29/0	-29/0	-35/-1	-35/-1	-35/-1	-42/-1	-42/-1	-51/-2	-59/-2
H7/r6	interference	-23/-3	-23/-3	-28/-4	-28/-4	-34/-5	-34/-5	-41/-7	-41/-7	-41/-7	-50/-9	-50/-9	-62/-13	-73/-16
H7/k6	transition	-9/+11	-9/+11	-10/+14	-10/+14	-12/+17	-12/+17	-15/+19	-15/+19	-15/+19	-18/+23	-18/+23	-21/+28	-25/+32
H7/m6	transition	-12/+8	-12/+8	-15/+9	-15/+9	-18/+11	-18/+11	-21/+13	-21/+13	-21/+13	-25/+16	-25/+16	-30/+19	-35/+22
H7/n6	transition	-16/+4	-16/+4	-19/+5	-19/+5	-23/+6	-23/+6	-28/+6	-28/+6	-28/+6	-33/+8	-33/+8	-39/+10	-45/+12
F8/h7	clearance	+10/+40	+10/+40	+13/+50	+13/+50	+16/+61	+16/+61	+20/+74	+20/+74	+20/+74	+25/+89	+25/+89	+30/+106	+36/+125
G7/h6	clearance	+4/+24	+4/+24	+5/+29	+5/+29	+6/+35	+6/+35	+7/+41	+7/+41	+7/+41	+9/+50	+9/+50	+10/+59	+12/+69
P7/h6	interference	-20/0	-20/0	-24/0	-24/0	-29/0	-29/0	-35/-1	-35/-1	-35/-1	-42/-1	-42/-1	-51/-2	-59/-2
K7/h6	transition	-9/+11	-9/+11	-10/+14	-10/+14	-12/+17	-12/+17	-15/+19	-15/+19	-15/+19	-18/+23	-18/+23	-21/+28	-25/+32
N7/h6	transition	-16/+4	-16/+4	-19/+5	-19/+5	-23/+6	-23/+6	-28/+6	-28/+6	-28/+6	-33/+8	-33/+8	-39/+10	-45/+12

Minimum clearance is the largest shaft in the smallest hole; maximum clearance is the smallest shaft in the largest hole. A transition fit spans zero, which is why both columns carry a sign.

Common Questions About ISO 286 Tolerances

What is the tolerance for a 25 mm H7 hole?: A 25 mm H7 hole runs 25.000 to 25.021 mm — 0 to +21 µm, because IT7 at that size band is 21 µm wide and H means the band starts at the nominal size.
What does the IT number in a tolerance like H7 or g6 mean?: It is the ISO 286 standard tolerance grade, and it sets how wide the band is for that nominal size. The grades in this chart run IT5 to IT12, each roughly 1.6× the width of the one before, and every one widens as the nominal size grows.
How do I read a fundamental deviation table?: The letter fixes the deviation nearest the nominal size — the position of the band — and the grade fixes its width. Capital letters are holes, lowercase are shafts. H and h are the zero-deviation cases: an H hole is never smaller than nominal and an h shaft is never larger.
Which nominal sizes does this chart cover?: The IT grade table covers the full ISO 286 range from 0 to 500 mm in 13 size bands. The per-designation and per-fit tables cover the 13 nominal sizes with verified demand: 5 mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 40 mm, 50 mm, 80 mm, 100 mm.

Sources and Method for This ISO 286 Tolerance Chart

ISO 286 IT grades, fundamental deviations and fitscompiled

saucecode/ISO286 (LGPL-2.1) + parkergreene/isofits (MIT), cross-checked cell-for-cell

Verified against fits-iso286: 2067 checks passed across 3 harness(es)

Compiled from independent public sources that agree cell-for-cell.

IT gradescompiled

ISO 286-1 IT grades and ISO 286-2 fundamental deviations, compiled from saucecode/ISO286 (LGPL-2.1) and parkergreene/isofits (MIT), cross-checked cell-for-cell

Verified against parkergreene/isofits ISO 286-2 limit tables (MIT); ISO 286-1 formula harness — 2067 checks passed. Formula per ISO 286-1 standard tolerance factor and fundamental deviation formulas, used as a validation harness only per docs/research/data-sourcing.md §3.6

Compiled from independent public sources that agree cell-for-cell.

Formula

Limits from a designation

max Ø  =  nominal + upper deviation
min Ø  =  nominal + lower deviation

Clearance of a fit

max clearance  =  hole max − shaft min
min clearance  =  hole min − shaft max

A negative result is interference.

Assumptions

All values apply at the ISO 286 reference temperature of 20 °C.
COMPILED, not computed: the ISO 286-1 formula deviates from the published table by up to 13.26%, so it is used here only as a validation harness (warn above 5%, fail above 15%) and never as the shipped number.
Dataset scope: COMPILED not computed: the ISO 286-1 formula deviates up to 13.26% from the table and is used only as a harness (warn >5%, fail >15%). EXCLUDED: shaft/hole letters s, t, u and the fits H7/s6, H7/t6, H7/u6 — no free source and an undetermined step constant in the formula.

Data last verified

August 1, 2026

How this data is built and checked →

How to Cite This ISO 286 Tolerance Chart

Citation

ShopMath. "ISO 286 Tolerance Chart — IT Grades, Deviations and Fits." ShopMath, verified August 1, 2026, https://shopmath.org/charts/iso-tolerances

BibTeX

@misc{shopmath-charts-iso-tolerances,
  title        = {ISO 286 Tolerance Chart — IT Grades, Deviations and Fits},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/charts/iso-tolerances}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/charts/iso-tolerances

Every ISO 286 designation and fit