What is the H7 tolerance for a 10 mm diameter?

For a diameter over 6 up to 10 mm, H7 is 0 / +15 µm: the hole measures 10.000 to 10.015 mm.

What is the difference between H7 and h7?

H7 (capital) applies to a hole: the lower deviation is zero and the tolerance lies above the nominal size. h7 (lower case) applies to a shaft: the upper deviation is zero and the tolerance lies below.

IT7 is the tolerance grade: the width of the tolerance zone, which also depends on the diameter. For a diameter of 18 to 30 mm, IT7 is 21 µm and IT6 is 13 µm.

Does the software work out fits by itself?

Yes. Bulleur PARFAIT reads “Ø20 H7” on the drawing and writes the min and max straight into the report, with no table to look up.

H7 tolerance and ISO 286 fits: table and calculator

Updated October 14, 2026

A dimension such as Ø20 H7 or Ø20 g6 does not show its deviations: they come from ISO 286. Enter the diameter and the classes: the calculator gives the min and max of the hole and the shaft, then the resulting clearance or interference.

ISO 286 fit calculator

Diameter (mm)

Hole

IT grade

Shaft

IT grade

Hole Ø20 H7

Upper deviation: +21 µm
Lower deviation: 0 µm
Max (mm): 20.021
Min (mm): 20.000

Shaft Ø20 g6

Upper deviation: −7 µm
Lower deviation: −20 µm
Max (mm): 19.993
Min (mm): 19.980

Clearance fit · min clearance 0.007 · max clearance 0.041 mm

A negative clearance is an interference. Positions calculated: d, e, f, g, h, js, k, m, n, p; grades IT4 to IT13; diameters up to 500 mm.

Common fits (hole-basis system)

From loosest to tightest, with their usual applications.

Fit	Type	Typical use
H11/d11	Clearance	Loose running: rough parts, low-precision pivot pins.
H9/e8	Clearance	Free running: high-speed bearings, long shafts.
H8/f7	Clearance	Close running: lubricated plain bearings, general guides.
H7/g6	Clearance	Sliding: sliding gears, pistons, precise guides.
H7/h6	Clearance	Locational clearance: spigots fitted and removed by hand.
H7/js6	Transition	Light transition: precise spigots removed with a mallet.
H7/k6	Transition	Transition: hubs, bearings on shafts, removed with a mallet.
H7/m6	Transition	Firm transition: parts located without sliding.
H7/n6	Transition	Tight transition: bushes and hubs pressed in lightly.
H7/p6	Interference	Interference: bushes and friction rings pressed in.

ISO 286 deviation table (µm)

Upper deviation on top, lower deviation below, in micrometres (1 µm = 0.001 mm).

Diameter (mm)	H7	H8	f7	g6	h6	js6	k6	m6	n6	p6
up to 3	+10 0	+14 0	−6 −16	−2 −8	0 −6	+3 −3	+6 0	+8 +2	+10 +4	+12 +6
over 3 to 6	+12 0	+18 0	−10 −22	−4 −12	0 −8	+4 −4	+9 +1	+12 +4	+16 +8	+20 +12
over 6 to 10	+15 0	+22 0	−13 −28	−5 −14	0 −9	+4.5 −4.5	+10 +1	+15 +6	+19 +10	+24 +15
over 10 to 18	+18 0	+27 0	−16 −34	−6 −17	0 −11	+5.5 −5.5	+12 +1	+18 +7	+23 +12	+29 +18
over 18 to 30	+21 0	+33 0	−20 −41	−7 −20	0 −13	+6.5 −6.5	+15 +2	+21 +8	+28 +15	+35 +22
over 30 to 50	+25 0	+39 0	−25 −50	−9 −25	0 −16	+8 −8	+18 +2	+25 +9	+33 +17	+42 +26
over 50 to 80	+30 0	+46 0	−30 −60	−10 −29	0 −19	+9.5 −9.5	+21 +2	+30 +11	+39 +20	+51 +32
over 80 to 120	+35 0	+54 0	−36 −71	−12 −34	0 −22	+11 −11	+25 +3	+35 +13	+45 +23	+59 +37
over 120 to 180	+40 0	+63 0	−43 −83	−14 −39	0 −25	+12.5 −12.5	+28 +3	+40 +15	+52 +27	+68 +43
over 180 to 250	+46 0	+72 0	−50 −96	−15 −44	0 −29	+14.5 −14.5	+33 +4	+46 +17	+60 +31	+79 +50
over 250 to 315	+52 0	+81 0	−56 −108	−17 −49	0 −32	+16 −16	+36 +4	+52 +20	+66 +34	+88 +56
over 315 to 400	+57 0	+89 0	−62 −119	−18 −54	0 −36	+18 −18	+40 +4	+57 +21	+73 +37	+98 +62
over 400 to 500	+63 0	+97 0	−68 −131	−20 −60	0 −40	+20 −20	+45 +5	+63 +23	+80 +40	+108 +68

How to read “Ø20 H7”

The number is the nominal diameter. The letter is the position of the tolerance relative to that diameter: capital for a hole, lower case for a shaft. The figure is the IT tolerance grade: the smaller it is, the tighter the tolerance. For Ø20 H7, the lower deviation is 0 and the upper deviation +21 µm: the hole must measure between 20.000 and 20.021 mm.

The hole-basis system (H)

In general engineering the hole is usually fixed at H (zero lower deviation) and the shaft is chosen for the fit required: f or g for a sliding fit, h or js for a precise removable location, k to p for a tight fit. It is cheaper, because H7 reamers and plug gauges are standard tools.

Clearance, transition or interference

Clearance: the shaft is always smaller than the hole (H7/g6, H8/f7).
Transition: depending on the parts, there is a slight clearance or a slight interference (H7/js6, H7/k6).
Interference: the shaft is always larger than the hole; pressed in or shrink-fitted (H7/p6).

Worked example

Ø20 H7/g6: the hole measures 20.000 to 20.021 mm, the shaft 19.980 to 19.993 mm. Minimum clearance is 20.000 − 19.993 = 0.007 mm and maximum clearance 20.021 − 19.980 = 0.041 mm: a sliding fit.

Frequently asked questions

What is the H7 tolerance for a 10 mm diameter?: For a diameter over 6 up to 10 mm, H7 is 0 / +15 µm: the hole measures 10.000 to 10.015 mm.
What is the difference between H7 and h7?: H7 (capital) applies to a hole: the lower deviation is zero and the tolerance lies above the nominal size. h7 (lower case) applies to a shaft: the upper deviation is zero and the tolerance lies below.
What does IT7 mean?: IT7 is the tolerance grade: the width of the tolerance zone, which also depends on the diameter. For a diameter of 18 to 30 mm, IT7 is 21 µm and IT6 is 13 µm.
Does the software work out fits by itself?: Yes. Bulleur PARFAIT reads “Ø20 H7” on the drawing and writes the min and max straight into the report, with no table to look up.