U7 tolerance (hole, IT7)
Hole tolerance class U7 per ISO 286-1:2010: fundamental deviation ES −18 … −517, grade IT7 (10 µm at ≤ 3 mm to 63 µm at 400–500 mm). For an exact size, open the calculator with U7 selected.
- Type
- Hole
- Grade
- IT7
- Tolerance
- 10 … 63 µm
- Fund. deviation
- ES −18 … −517 µm
U7 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | −18 | −28 | 2.982 | 2.972 | −0.018 | −0.028 | −0.00071 / −0.00110 |
| 3 – 6 | −19 | −31 | 5.981 | 5.969 | −0.019 | −0.031 | −0.00075 / −0.00122 |
| 6 – 10 | −22 | −37 | 9.978 | 9.963 | −0.022 | −0.037 | −0.00087 / −0.00146 |
| 10 – 14 | −26 | −44 | 13.974 | 13.956 | −0.026 | −0.044 | −0.00102 / −0.00173 |
| 14 – 18 | −26 | −44 | 17.974 | 17.956 | −0.026 | −0.044 | −0.00102 / −0.00173 |
| 18 – 24 | −33 | −54 | 23.967 | 23.946 | −0.033 | −0.054 | −0.00130 / −0.00213 |
| 24 – 30 | −40 | −61 | 29.960 | 29.939 | −0.040 | −0.061 | −0.00157 / −0.00240 |
| 30 – 40 | −51 | −76 | 39.949 | 39.924 | −0.051 | −0.076 | −0.00201 / −0.00299 |
| 40 – 50 | −61 | −86 | 49.939 | 49.914 | −0.061 | −0.086 | −0.00240 / −0.00339 |
| 50 – 65 | −76 | −106 | 64.924 | 64.894 | −0.076 | −0.106 | −0.00299 / −0.00417 |
| 65 – 80 | −91 | −121 | 79.909 | 79.879 | −0.091 | −0.121 | −0.00358 / −0.00476 |
| 80 – 100 | −111 | −146 | 99.889 | 99.854 | −0.111 | −0.146 | −0.00437 / −0.00575 |
| 100 – 120 | −131 | −166 | 119.869 | 119.834 | −0.131 | −0.166 | −0.00516 / −0.00654 |
| 120 – 140 | −155 | −195 | 139.845 | 139.805 | −0.155 | −0.195 | −0.00610 / −0.00768 |
| 140 – 160 | −175 | −215 | 159.825 | 159.785 | −0.175 | −0.215 | −0.00689 / −0.00846 |
| 160 – 180 | −195 | −235 | 179.805 | 179.765 | −0.195 | −0.235 | −0.00768 / −0.00925 |
| 180 – 200 | −219 | −265 | 199.781 | 199.735 | −0.219 | −0.265 | −0.00862 / −0.01043 |
| 200 – 225 | −241 | −287 | 224.759 | 224.713 | −0.241 | −0.287 | −0.00949 / −0.01130 |
| 225 – 250 | −267 | −313 | 249.733 | 249.687 | −0.267 | −0.313 | −0.01051 / −0.01232 |
| 250 – 280 | −295 | −347 | 279.705 | 279.653 | −0.295 | −0.347 | −0.01161 / −0.01366 |
| 280 – 315 | −330 | −382 | 314.670 | 314.618 | −0.330 | −0.382 | −0.01299 / −0.01504 |
| 315 – 355 | −369 | −426 | 354.631 | 354.574 | −0.369 | −0.426 | −0.01453 / −0.01677 |
| 355 – 400 | −414 | −471 | 399.586 | 399.529 | −0.414 | −0.471 | −0.01630 / −0.01854 |
| 400 – 450 | −467 | −530 | 449.533 | 449.470 | −0.467 | −0.530 | −0.01839 / −0.02087 |
| 450 – 500 | −517 | −580 | 499.483 | 499.420 | −0.517 | −0.580 | −0.02035 / −0.02283 |
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 U7
U7 denotes a hole tolerance zone with heavy interference deviation in the ISO 286 system. It is used in U7/h6 (Shaft-basis equivalent of H7/u6.).
At Ø25 mm U7 is −0.040 / −0.061 mm, i.e. 24.939 to 24.960 mm.
How the limits are calculated
U7 uses grade IT7 (a standard tolerance of 21 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); IT7 sets the width below ES. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.