X7 tolerance (hole, IT7)

Hole tolerance class X7 per ISO 286-1:2010: fundamental deviation ES −20 … −797, grade IT7 (10 µm at ≤ 3 mm to 63 µm at 400–500 mm). For an exact size, open the calculator with X7 selected.

Type: Hole
Grade: IT7
Tolerance: 10 … 63 µm
Fund. deviation: ES −20 … −797 µm

X7 limits by size range

Size (mm)	Upper (µm)	Lower (µm)	Ø max (mm)	Ø min (mm)	Upper (mm)	Lower (mm)	Dev. (in)
≤ 3	−20	−30	2.980	2.970	−0.020	−0.030	−0.00079 / −0.00118
3 – 6	−24	−36	5.976	5.964	−0.024	−0.036	−0.00094 / −0.00142
6 – 10	−28	−43	9.972	9.957	−0.028	−0.043	−0.00110 / −0.00169
10 – 14	−33	−51	13.967	13.949	−0.033	−0.051	−0.00130 / −0.00201
14 – 18	−38	−56	17.962	17.944	−0.038	−0.056	−0.00150 / −0.00220
18 – 24	−46	−67	23.954	23.933	−0.046	−0.067	−0.00181 / −0.00264
24 – 30	−56	−77	29.944	29.923	−0.056	−0.077	−0.00220 / −0.00303
30 – 40	−71	−96	39.929	39.904	−0.071	−0.096	−0.00280 / −0.00378
40 – 50	−88	−113	49.912	49.887	−0.088	−0.113	−0.00346 / −0.00445
50 – 65	−111	−141	64.889	64.859	−0.111	−0.141	−0.00437 / −0.00555
65 – 80	−135	−165	79.865	79.835	−0.135	−0.165	−0.00531 / −0.00650
80 – 100	−165	−200	99.835	99.800	−0.165	−0.200	−0.00650 / −0.00787
100 – 120	−197	−232	119.803	119.768	−0.197	−0.232	−0.00776 / −0.00913
120 – 140	−233	−273	139.767	139.727	−0.233	−0.273	−0.00917 / −0.01075
140 – 160	−265	−305	159.735	159.695	−0.265	−0.305	−0.01043 / −0.01201
160 – 180	−295	−335	179.705	179.665	−0.295	−0.335	−0.01161 / −0.01319
180 – 200	−333	−379	199.667	199.621	−0.333	−0.379	−0.01311 / −0.01492
200 – 225	−368	−414	224.632	224.586	−0.368	−0.414	−0.01449 / −0.01630
225 – 250	−408	−454	249.592	249.546	−0.408	−0.454	−0.01606 / −0.01787
250 – 280	−455	−507	279.545	279.493	−0.455	−0.507	−0.01791 / −0.01996
280 – 315	−505	−557	314.495	314.443	−0.505	−0.557	−0.01988 / −0.02193
315 – 355	−569	−626	354.431	354.374	−0.569	−0.626	−0.02240 / −0.02465
355 – 400	−639	−696	399.361	399.304	−0.639	−0.696	−0.02516 / −0.02740
400 – 450	−717	−780	449.283	449.220	−0.717	−0.780	−0.02823 / −0.03071
450 – 500	−797	−860	499.203	499.140	−0.797	−0.860	−0.03138 / −0.03386

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 X7

X7 denotes a hole tolerance zone with heavy interference deviation in the ISO 286 system.

At Ø25 mm X7 is −0.056 / −0.077 mm, i.e. 24.923 to 24.944 mm.

How the limits are calculated

X7 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.