Tolerance chart
E8 tolerance (hole): ISO 286 chart up to 500 mm
E8 is an ISO tolerance class for holes (internal features) under ISO 286. At Ø25 mm it means +73 / +40 µm: the size may lie between 25.040 and 25.073 mm. Below are the deviations for every nominal size up to 500 mm and the fits that use E8.
E8 chart: deviations for all nominal sizes up to 500 mm
Deviations in µm (1 µm = 0.001 mm). A nominal size belongs to the row »over … up to and including …«: exactly 30 mm is in the row ending at 30, 30.1 mm in the next one.
| Nominal size over – to (mm) | Upper deviation | Lower deviation | Tolerance |
|---|---|---|---|
| 0 – 3 | +28 | +14 | 14 |
| 3 – 6 | +38 | +20 | 18 |
| 6 – 10 | +47 | +25 | 22 |
| 10 – 18 | +59 | +32 | 27 |
| 18 – 30 | +73 | +40 | 33 |
| 30 – 50 | +89 | +50 | 39 |
| 50 – 80 | +106 | +60 | 46 |
| 80 – 120 | +126 | +72 | 54 |
| 120 – 180 | +148 | +85 | 63 |
| 180 – 250 | +172 | +100 | 72 |
| 250 – 315 | +191 | +110 | 81 |
| 315 – 400 | +214 | +125 | 89 |
| 400 – 500 | +232 | +135 | 97 |
E8 for your nominal size
How E8 is built
An ISO tolerance class is a letter and a number. Capital letters stand for holes, small letters for shafts. The letter E sets the position of the tolerance zone; at Ø25 mm it lies entirely above the nominal size: the hole is always larger than nominal. The number 8 is the standard tolerance grade IT8: it sets how wide the zone is – 33 µm at Ø25 mm.
The tolerance grows with the nominal size: 14 µm in the smallest row (0 – 3 mm), 97 µm in the largest (400 – 500 mm). On a drawing the class follows the dimension, as in »Ø25 E8«; the inspection plan turns that into the limits 25.040 and 25.073 mm.
Fits with E8 at Ø25 mm
Shaft-basis system: the shaft is h, the hole E8. Clearance in µm; a minus means interference. Sorted from the largest minimum clearance to the largest interference.
Frequently asked questions about E8
What does E8 mean?
E8 is an ISO tolerance class for holes (internal features): the letter E sets the position of the tolerance zone, the number 8 the standard tolerance grade IT8. At Ø25 mm that gives +73 / +40 µm, i.e. 25.040 to 25.073 mm.
What are the E8 limits at Ø10 and Ø50 mm?
Ø10 E8: +47 / +25 µm (10.025 to 10.047 mm). Ø50 E8: +89 / +50 µm (50.050 to 50.089 mm).
Is E8 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. E8/h7 at Ø25 mm is a clearance fit (maximum clearance 94 µm, minimum clearance 40 µm; a minus means interference).
More tolerance classes
Same letter E, other grades: E9
All classes at a glance: ISO 286 tolerance charts. The same chart in German: E8 Toleranz.