M8 tolerance (hole, IT8)
Hole tolerance class M8 per ISO 286-1:2010: fundamental deviation ES −2 … +11, grade IT8 (14 µm at ≤ 3 mm to 97 µm at 400–500 mm). For an exact size, open the calculator with M8 selected.
- Type
- Hole
- Grade
- IT8
- Tolerance
- 14 … 97 µm
- Fund. deviation
- ES −2 … +11 µm
M8 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | −2 | −16 | 2.998 | 2.984 | −0.002 | −0.016 | −0.00008 / −0.00063 |
| 3 – 6 | +2 | −16 | 6.002 | 5.984 | +0.002 | −0.016 | +0.00008 / −0.00063 |
| 6 – 10 | +1 | −21 | 10.001 | 9.979 | +0.001 | −0.021 | +0.00004 / −0.00083 |
| 10 – 14 | +2 | −25 | 14.002 | 13.975 | +0.002 | −0.025 | +0.00008 / −0.00098 |
| 14 – 18 | +2 | −25 | 18.002 | 17.975 | +0.002 | −0.025 | +0.00008 / −0.00098 |
| 18 – 24 | +4 | −29 | 24.004 | 23.971 | +0.004 | −0.029 | +0.00016 / −0.00114 |
| 24 – 30 | +4 | −29 | 30.004 | 29.971 | +0.004 | −0.029 | +0.00016 / −0.00114 |
| 30 – 40 | +5 | −34 | 40.005 | 39.966 | +0.005 | −0.034 | +0.00020 / −0.00134 |
| 40 – 50 | +5 | −34 | 50.005 | 49.966 | +0.005 | −0.034 | +0.00020 / −0.00134 |
| 50 – 65 | +5 | −41 | 65.005 | 64.959 | +0.005 | −0.041 | +0.00020 / −0.00161 |
| 65 – 80 | +5 | −41 | 80.005 | 79.959 | +0.005 | −0.041 | +0.00020 / −0.00161 |
| 80 – 100 | +6 | −48 | 100.006 | 99.952 | +0.006 | −0.048 | +0.00024 / −0.00189 |
| 100 – 120 | +6 | −48 | 120.006 | 119.952 | +0.006 | −0.048 | +0.00024 / −0.00189 |
| 120 – 140 | +8 | −55 | 140.008 | 139.945 | +0.008 | −0.055 | +0.00031 / −0.00217 |
| 140 – 160 | +8 | −55 | 160.008 | 159.945 | +0.008 | −0.055 | +0.00031 / −0.00217 |
| 160 – 180 | +8 | −55 | 180.008 | 179.945 | +0.008 | −0.055 | +0.00031 / −0.00217 |
| 180 – 200 | +9 | −63 | 200.009 | 199.937 | +0.009 | −0.063 | +0.00035 / −0.00248 |
| 200 – 225 | +9 | −63 | 225.009 | 224.937 | +0.009 | −0.063 | +0.00035 / −0.00248 |
| 225 – 250 | +9 | −63 | 250.009 | 249.937 | +0.009 | −0.063 | +0.00035 / −0.00248 |
| 250 – 280 | +9 | −72 | 280.009 | 279.928 | +0.009 | −0.072 | +0.00035 / −0.00283 |
| 280 – 315 | +9 | −72 | 315.009 | 314.928 | +0.009 | −0.072 | +0.00035 / −0.00283 |
| 315 – 355 | +11 | −78 | 355.011 | 354.922 | +0.011 | −0.078 | +0.00043 / −0.00307 |
| 355 – 400 | +11 | −78 | 400.011 | 399.922 | +0.011 | −0.078 | +0.00043 / −0.00307 |
| 400 – 450 | +11 | −86 | 450.011 | 449.914 | +0.011 | −0.086 | +0.00043 / −0.00339 |
| 450 – 500 | +11 | −86 | 500.011 | 499.914 | +0.011 | −0.086 | +0.00043 / −0.00339 |
Deviations at the upper end of each range (Ø columns use that size); use the calculator for the exact size. — : not defined by ISO 286 for that size. Upper/Lower (mm) and inch columns are shown on wider screens.
About M8
M8 denotes a hole tolerance zone with tight transition deviation in the ISO 286 system.
At Ø25 mm M8 is +0.004 / −0.029 mm, i.e. 24.971 to 25.004 mm.
How the limits are calculated
M8 uses grade IT8 (a standard tolerance of 33 µm at 18–30 mm). Fundamental deviation: ES = −ei + Δ (Δ = ITn − IT(n−1), applied up to IT8 for K/M/N and IT7 otherwise); IT8 sets the width below ES. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.