Tolerance chart
K7 tolerance (hole): ISO 286 chart up to 500 mm
K7 is an ISO tolerance class for holes (internal features) under ISO 286. At Ø25 mm it means +6 / −15 µm: the size may lie between 24.985 and 25.006 mm. Below are the deviations for every nominal size up to 500 mm and the fits that use K7.
K7 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 | 0 | −10 | 10 |
| 3 – 6 | +3 | −9 | 12 |
| 6 – 10 | +5 | −10 | 15 |
| 10 – 18 | +6 | −12 | 18 |
| 18 – 30 | +6 | −15 | 21 |
| 30 – 50 | +7 | −18 | 25 |
| 50 – 80 | +9 | −21 | 30 |
| 80 – 120 | +10 | −25 | 35 |
| 120 – 180 | +12 | −28 | 40 |
| 180 – 250 | +13 | −33 | 46 |
| 250 – 315 | +16 | −36 | 52 |
| 315 – 400 | +17 | −40 | 57 |
| 400 – 500 | +18 | −45 | 63 |
K7 for your nominal size
How K7 is built
An ISO tolerance class is a letter and a number. Capital letters stand for holes, small letters for shafts. The letter K sets the position of the tolerance zone; at Ø25 mm it lies on both sides of the nominal size. The number 7 is the standard tolerance grade IT7: it sets how wide the zone is – 21 µm at Ø25 mm.
The tolerance grows with the nominal size: 10 µm in the smallest row (0 – 3 mm), 63 µm in the largest (400 – 500 mm). On a drawing the class follows the dimension, as in »Ø25 K7«; the inspection plan turns that into the limits 24.985 and 25.006 mm.
Fits with K7 at Ø25 mm
Shaft-basis system: the shaft is h, the hole K7. Clearance in µm; a minus means interference. Sorted from the largest minimum clearance to the largest interference.
Frequently asked questions about K7
What does K7 mean?
K7 is an ISO tolerance class for holes (internal features): the letter K sets the position of the tolerance zone, the number 7 the standard tolerance grade IT7. At Ø25 mm that gives +6 / −15 µm, i.e. 24.985 to 25.006 mm.
What are the K7 limits at Ø10 and Ø50 mm?
Ø10 K7: +5 / −10 µm (9.990 to 10.005 mm). Ø50 K7: +7 / −18 µm (49.982 to 50.007 mm).
Is K7 a clearance fit?
A tolerance class on its own is not a fit – only together with its mating part. K7/h6 at Ø25 mm is a transition fit (maximum clearance 19 µm, minimum clearance −15 µm; a minus means interference).
More tolerance classes
Same letter K, other grades: K6
Holes in grade 7: H7 · G7 · F7 · JS7 · M7 · N7 · P7 · R7 · S7
All classes at a glance: ISO 286 tolerance charts. The same chart in German: K7 Toleranz.