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H7 Tolerance Chart

ISO 286 limits for H7 holes and the shafts that go with them (h6, g6, f7, k6, m6, n6, p6, r6, s6), by size up to 500 mm. Deviations in µm.

H7 hole tolerance by size

H7 hole limits (ISO 286-2): EI = 0, ES = +IT7
Size over – to (mm)IT7 (µm)Upper ES (µm)Lower EI (µm)
≤ 310+100
3 – 612+120
6 – 1015+150
10 – 1818+180
18 – 3021+210
30 – 5025+250
50 – 8030+300
80 – 12035+350
120 – 18040+400
180 – 25046+460
250 – 31552+520
315 – 40057+570
400 – 50063+630

A size belongs to the row where it is over the first value and up to and including the second (30 mm is in 18 – 30). Add the deviations to the nominal size for the limits: Ø25 H7 is 25.000 to 25.021 mm.

Ø25 H7: upper +21 µm, lower 0 µm → 25.000 to 25.021 mm (tolerance 21 µm)

Companion zones: H6, H8, h6, h7, g6, f7, k6, m6, n6, p6, r6, s6

Each cell reads upper / lower deviation in µm. The tables are generated from the same verified ISO 286 data as the fit calculator; r and s shafts change deviation inside the coarse size bands above 50 mm, so they get their own finer rows.

Hole zones H6, H7, H8 (upper / lower deviation, µm)
Size over – to (mm)H6H7H8
≤ 3+6 / 0+10 / 0+14 / 0
3 – 6+8 / 0+12 / 0+18 / 0
6 – 10+9 / 0+15 / 0+22 / 0
10 – 18+11 / 0+18 / 0+27 / 0
18 – 30+13 / 0+21 / 0+33 / 0
30 – 50+16 / 0+25 / 0+39 / 0
50 – 80+19 / 0+30 / 0+46 / 0
80 – 120+22 / 0+35 / 0+54 / 0
120 – 180+25 / 0+40 / 0+63 / 0
180 – 250+29 / 0+46 / 0+72 / 0
250 – 315+32 / 0+52 / 0+81 / 0
315 – 400+36 / 0+57 / 0+89 / 0
400 – 500+40 / 0+63 / 0+97 / 0
Shaft zones h6, h7, g6, f7 (upper / lower deviation, µm)
Size over – to (mm)h6h7g6f7
≤ 30 / −60 / −10−2 / −8−6 / −16
3 – 60 / −80 / −12−4 / −12−10 / −22
6 – 100 / −90 / −15−5 / −14−13 / −28
10 – 180 / −110 / −18−6 / −17−16 / −34
18 – 300 / −130 / −21−7 / −20−20 / −41
30 – 500 / −160 / −25−9 / −25−25 / −50
50 – 800 / −190 / −30−10 / −29−30 / −60
80 – 1200 / −220 / −35−12 / −34−36 / −71
120 – 1800 / −250 / −40−14 / −39−43 / −83
180 – 2500 / −290 / −46−15 / −44−50 / −96
250 – 3150 / −320 / −52−17 / −49−56 / −108
315 – 4000 / −360 / −57−18 / −54−62 / −119
400 – 5000 / −400 / −63−20 / −60−68 / −131
Shaft zones k6, m6, n6, p6 (upper / lower deviation, µm)
Size over – to (mm)k6m6n6p6
≤ 3+6 / 0+8 / +2+10 / +4+12 / +6
3 – 6+9 / +1+12 / +4+16 / +8+20 / +12
6 – 10+10 / +1+15 / +6+19 / +10+24 / +15
10 – 18+12 / +1+18 / +7+23 / +12+29 / +18
18 – 30+15 / +2+21 / +8+28 / +15+35 / +22
30 – 50+18 / +2+25 / +9+33 / +17+42 / +26
50 – 80+21 / +2+30 / +11+39 / +20+51 / +32
80 – 120+25 / +3+35 / +13+45 / +23+59 / +37
120 – 180+28 / +3+40 / +15+52 / +27+68 / +43
180 – 250+33 / +4+46 / +17+60 / +31+79 / +50
250 – 315+36 / +4+52 / +20+66 / +34+88 / +56
315 – 400+40 / +4+57 / +21+73 / +37+98 / +62
400 – 500+45 / +5+63 / +23+80 / +40+108 / +68
Shaft zones r6 and s6 (finer size steps above 50 mm, µm)
Size over – to (mm)r6s6
≤ 3+16 / +10+20 / +14
3 – 6+23 / +15+27 / +19
6 – 10+28 / +19+32 / +23
10 – 18+34 / +23+39 / +28
18 – 30+41 / +28+48 / +35
30 – 50+50 / +34+59 / +43
50 – 65+60 / +41+72 / +53
65 – 80+62 / +43+78 / +59
80 – 100+73 / +51+93 / +71
100 – 120+76 / +54+101 / +79
120 – 140+88 / +63+117 / +92
140 – 160+90 / +65+125 / +100
160 – 180+93 / +68+133 / +108
180 – 200+106 / +77+151 / +122
200 – 225+109 / +80+159 / +130
225 – 250+113 / +84+169 / +140
250 – 280+126 / +94+190 / +158
280 – 315+130 / +98+202 / +170
315 – 355+144 / +108+226 / +190
355 – 400+150 / +114+244 / +208
400 – 450+166 / +126+272 / +232
450 – 500+172 / +132+292 / +252

What H7 means

An ISO 286 tolerance class is a letter plus a number. The number is the IT grade: the width of the tolerance zone, which grows with size (IT7 is 21 µm at 25 mm and 25 µm at 40 mm). The letter places that zone relative to the nominal size. Capital letters are holes, lowercase letters are shafts. H is the one hole zone that starts exactly at nominal: lower deviation EI = 0 and upper deviation ES = +IT7. That is why most drawings use hole-basis: standard drills and reamers produce H7 holes, and you vary the shaft letter to change the fit. The shaft side mirrors it: h ends at nominal (es = 0), g and f sit just below it, k, m, n, p, r and s move above it.

Typical pairings with an H7 hole: H7/g6 sliding fit (always clearance, for slide and rotating parts with lubricant), H7/h6 close locating clearance, H7/k6 transition fit (precise location, light assembly force), H7/p6 light press fit (interference). For H8 holes with h7 or f7 shafts the tolerance is wider and cheaper to produce.

Worked example: Ø25 H7/h6, H7/g6, H7/k6 and H7/p6

Next steps: compute the full clearance or interference for any pair with the ISO 286 fit calculator, the pressure and force of an interference with the press fit calculator, and read ISO 286 fit selection and ISO 286 fits explained for how to choose. SuperNX reads ISO 286 fits straight from NX PMI so the same values feed your tolerance chain.

FAQ

What is the H7 tolerance?

H7 is an ISO 286 hole tolerance class: the lower deviation is zero and the upper deviation equals the IT7 tolerance width, which depends on size. For a 25 mm hole IT7 is 21 µm, so H7 means 25.000 to 25.021 mm.

What is the difference between H7 and h6?

The capital letter H is a hole, the lowercase h is a shaft. H7 starts at the nominal size and grows by IT7; h6 ends at the nominal size and shrinks by IT6. At 25 mm H7 is 0 / +21 µm and h6 is 0 / −13 µm, so H7/h6 always leaves between 0 and 34 µm of clearance: a locating fit.

How do I read an H7 tolerance chart?

Find the row whose size range contains your nominal diameter (over the lower value, up to and including the upper), then read the upper and lower deviation in micrometres. Add them to the nominal size to get the limits. Sizes exactly on a boundary belong to the smaller band, so 30 mm uses 18 – 30.

Which shaft goes with an H7 hole?

g6 for a sliding fit, h6 for close locating with clearance, k6 for a transition fit (accurate location, light press) and p6 (or r6 and s6) for a press fit. Use the fit calculator to see the clearance or interference for your size.

Are these values from ISO 286?

Yes. They come from the published ISO 286-1 / ISO 286-2 tables for sizes up to 500 mm, the same data behind the free fit calculator. They are reference values: verify against the current standard before releasing production drawings.