EN简繁VI

ISO 286 hole tolerance chart and fit calculator

Ø8 h6 = 0 / −0.009 mm: the shaft is 7.991 to 8.000 mm (h6: upper deviation 0, lower deviation −9 µm).

Need another size? Use the calculator below →

Quick chart: h6, h7 and H7 tolerances for Ø3–Ø50 mm

Values are upper / lower deviation in µm (1 µm = 0.001 mm). An h shaft has an upper deviation of 0; an H hole has a lower deviation of 0.

Quick chart: h6, h7 and H7 tolerances for Ø3–Ø50 mm
Nominal Ø (mm)Size step (mm)h6 shaft (µm)h7 shaft (µm)H7 hole (µm)
Ø31–30 / −60 / −10+10 / 0
Ø43–60 / −80 / −12+12 / 0
Ø53–60 / −80 / −12+12 / 0
Ø63–60 / −80 / −12+12 / 0
Ø86–100 / −90 / −15+15 / 0
Ø106–100 / −90 / −15+15 / 0
Ø1210–180 / −110 / −18+18 / 0
Ø1410–180 / −110 / −18+18 / 0
Ø1610–180 / −110 / −18+18 / 0
Ø1810–180 / −110 / −18+18 / 0
Ø2018–300 / −130 / −21+21 / 0
Ø2218–300 / −130 / −21+21 / 0
Ø2518–300 / −130 / −21+21 / 0
Ø2818–300 / −130 / −21+21 / 0
Ø3018–300 / −130 / −21+21 / 0
Ø3230–500 / −160 / −25+25 / 0
Ø3530–500 / −160 / −25+25 / 0
Ø4030–500 / −160 / −25+25 / 0
Ø4530–500 / −160 / −25+25 / 0
Ø5030–500 / −160 / −25+25 / 0

Source: ISO 286-1:2010 (standard tolerance grades IT6 and IT7, fundamental deviations h and H). A size exactly on a step limit (3, 6, 10, 18, 30, 50 mm) belongs to the smaller step.

When you request a quote, state the tolerances and accuracy grades on the drawing: see the RFQ preparation checklist.

Enter a nominal size and choose hole and shaft tolerance classes to get deviations, limit sizes and clearance or interference.

Common fits: H7/g6 (sliding), H7/h6 (locating), H7/k6 (transition), H7/p6 (press).

Send us this part and we will recommend a suitable machine Request a quote →

Up next

ToolThread and tap drill calculatorTap drills for metric M1–M39 with minor diameter ranges (M10 uses 8.5 mm), forming taps, UNC/UNF/UNEF, G, R/Rc/Rp and NPT/NPS pipe threads, trapezoidal and Helicoil, plus a thread-turning calculator.ToolSurface roughness conversionConvert Ra to ISO 1302 N grades, Ra in microinches, estimated Rz, old ∇1–∇14 classes (GOST) and old JIS triangle marks, with typical machining methods.ArticleHow to prepare a CNC machine RFQ: 8 things to includeThe 8 pieces of information to prepare before asking for a CNC machine quote, so you get the right machine, configuration and comparable quotes. With a checklist.

Share the result with colleagues, or send it to CNCVIA for free advice.

Need another CNC machine for your shop? Send your drawing, material and volume for free recommendations and a quote.

Quick question on Zalo
📘 Free download: CNC machine buyer's guide 2026 (PDF) →
  • Data from the ISO 286 standard tolerance and fundamental deviation tables. For k shafts outside grades IT4–IT7, the lower deviation is 0.

Hole tolerance chart H6–H11 (µm)

The lower deviation of an H hole is always 0; values shown are the upper deviation. Example Ø50 H9: +62 / 0, so the hole is 50.000 to 50.062 mm.

Size (mm)H6H7H8H9H10H11
≤3+6 / 0+10 / 0+14 / 0+25 / 0+40 / 0+60 / 0
3–6+8 / 0+12 / 0+18 / 0+30 / 0+48 / 0+75 / 0
6–10+9 / 0+15 / 0+22 / 0+36 / 0+58 / 0+90 / 0
10–18+11 / 0+18 / 0+27 / 0+43 / 0+70 / 0+110 / 0
18–30+13 / 0+21 / 0+33 / 0+52 / 0+84 / 0+130 / 0
30–50+16 / 0+25 / 0+39 / 0+62 / 0+100 / 0+160 / 0
50–80+19 / 0+30 / 0+46 / 0+74 / 0+120 / 0+190 / 0
80–120+22 / 0+35 / 0+54 / 0+87 / 0+140 / 0+220 / 0
120–180+25 / 0+40 / 0+63 / 0+100 / 0+160 / 0+250 / 0
180–250+29 / 0+46 / 0+72 / 0+115 / 0+185 / 0+290 / 0
250–315+32 / 0+52 / 0+81 / 0+130 / 0+210 / 0+320 / 0
315–400+36 / 0+57 / 0+89 / 0+140 / 0+230 / 0+360 / 0
400–500+40 / 0+63 / 0+97 / 0+155 / 0+250 / 0+400 / 0

H9 hole tolerance (ISO 286)

An H9 hole has a lower deviation of 0 and an upper deviation equal to the standard tolerance IT9, so the hole is never smaller than the nominal size. IT9 is a medium-precision grade, used where H7 is tighter than the job needs; a common fit is H9/d9 (free running clearance fit). To check H9/d9, choose hole H9, shaft d, grade 9 in the calculator above.

Size (mm)H9 deviation (µm)ExampleHole size (mm)
≤3+25 / 0Ø3 H93.000 – 3.025
3–6+30 / 0Ø6 H96.000 – 6.030
6–10+36 / 0Ø10 H910.000 – 10.036
10–18+43 / 0Ø18 H918.000 – 18.043
18–30+52 / 0Ø30 H930.000 – 30.052
30–50+62 / 0Ø50 H950.000 – 50.062
50–80+74 / 0Ø80 H980.000 – 80.074
80–120+87 / 0Ø120 H9120.000 – 120.087
120–180+100 / 0Ø180 H9180.000 – 180.100
180–250+115 / 0Ø250 H9250.000 – 250.115
250–315+130 / 0Ø315 H9315.000 – 315.130
315–400+140 / 0Ø400 H9400.000 – 400.140
400–500+155 / 0Ø500 H9500.000 – 500.155

H7, g6, h6, k6, p6 tolerance chart (µm)

Values are upper / lower deviation in µm per ISO 286. Example Ø50 H7: +25 / 0, so the hole is 50.000 to 50.025 mm.

Size (mm)H7g6h6k6p6
≤3+10 / 0-2 / -80 / -6+6 / 0+12 / +6
3–6+12 / 0-4 / -120 / -8+9 / +1+20 / +12
6–10+15 / 0-5 / -140 / -9+10 / +1+24 / +15
10–18+18 / 0-6 / -170 / -11+12 / +1+29 / +18
18–30+21 / 0-7 / -200 / -13+15 / +2+35 / +22
30–50+25 / 0-9 / -250 / -16+18 / +2+42 / +26
50–80+30 / 0-10 / -290 / -19+21 / +2+51 / +32
80–120+35 / 0-12 / -340 / -22+25 / +3+59 / +37
120–180+40 / 0-14 / -390 / -25+28 / +3+68 / +43
180–250+46 / 0-15 / -440 / -29+33 / +4+79 / +50
250–315+52 / 0-17 / -490 / -32+36 / +4+88 / +56
315–400+57 / 0-18 / -540 / -36+40 / +4+98 / +62
400–500+63 / 0-20 / -600 / -40+45 / +5+108 / +68

h6, h7 and H7: frequently asked questions

What is Ø8 h6?

Ø8 h6 has an upper deviation of 0 and a lower deviation of −9 µm (−0.009 mm), so the shaft is 7.991 to 8.000 mm. Ø8 falls in the 6–10 mm size step, where IT6 is 9 µm.

What is the difference between h6 and h7?

Both are shafts with an upper deviation of 0, so the maximum size equals the nominal size. The difference is the width of the tolerance band: IT6 is tighter than IT7. At Ø8, h6 is 0 / −9 µm and h7 is 0 / −15 µm. h6 is more precise but costs more to machine and inspect; use h7 when the fit is less demanding.

What kind of fit is H7/h6?

H7/h6 is a close clearance fit used to locate parts (often called a sliding fit). At Ø8: the H7 hole is +15 / 0 µm and the h6 shaft is 0 / −9 µm, so the minimum clearance is 0 and the maximum is 24 µm (0.024 mm). The parts can be assembled by hand and still stay well centered.

Related tools

Inch – mm converter and drill sizes

Convert inches and fractional inches to mm and back, and find the nearest number (#1–#80), letter (A–Z) and fractional drill, with full charts.

Steel grade equivalents

Find equivalent grades of steel, stainless, cast iron, aluminum and copper alloys across JIS, GB, AISI/ASTM, DIN/EN and TCVN. Example: 1045 = S45C = C45 = 45.

Hardness conversion HRC – HV – HB

Convert steel hardness between Rockwell HRC, Vickers HV and Brinell HB per ASTM E140, with estimated tensile strength and an HRC 20–68 chart.

Chat on Zalo