Method
Equation
Limit size = nominal + deviation / 1000Cmin = Hmin − SmaxCmax = Hmax − SminTolerances
ISO 286 Fits & Tolerances Calculator
Enter the basic diameter, choose Hole or Shaft, then select the tolerance letter and grade from the drawing. Dimvo immediately returns the permitted minimum, maximum and midpoint target, followed by a practical mating-part suggestion and the resulting clearance or interference.
Decimal points and decimal commas are accepted.
Common diametersmm
Choose the letter and grade from the drawing. Select Custom pairing to control both components yourself, or choose a function when you want Dimvo to suggest a common combination.
Exact fit result
Hole H7 · Ø25 mm
Permitted hole size
25.000–25.021 mm
Tolerance midpoint
25.0105 mm
Nominal / basic size
25.000 mm
Tolerance width
21 µm
The midpoint is the centre of the permitted size range. The drawing’s nominal/basic size remains Ø25.000 mm.
Recommended shaft
g6 · 24.980–24.993 mm
A common starting point for accurate guidance while retaining guaranteed clearance.
- Midpoint
- 24.9865 mm
- Deviation
- -20 µm to -7 µm
H7/g6 · clearance fit
7–41 µm clearanceMinimum relation
+7 µm clearance
Maximum relation
+41 µm clearance
Show both component limits and deviations
| Part | Lower deviation | Upper deviation | Minimum | Maximum |
|---|---|---|---|---|
| Hole H7 | 0 µm | +21 µm | 25 | 25.021 |
| Shaft g6 | -20 µm | -7 µm | 24.98 | 24.993 |
Reference calculation at 20 °C. Check surface finish, form, coating, temperature, load, lubrication, assembly force and process capability before release.
Report an incorrect resultRecommendations
Preferred hole-basis fits at Ø25 mm
| Use | Fit | Type | Minimum | Maximum |
|---|---|---|---|---|
| H8/f7 | clearance | +20 µm clearance | +74 µm clearance | |
| H7/g6 | clearance | +7 µm clearance | +41 µm clearance | |
| H7/h6 | clearance | 0 µm line-to-line | +34 µm clearance | |
| H7/js6 | transition | 6.5 µm interference | +27.5 µm clearance | |
| H7/k6 | transition | 15 µm interference | +19 µm clearance | |
| H7/m6 | transition | 21 µm interference | +13 µm clearance | |
| H7/n6 | transition | 28 µm interference | +6 µm clearance | |
| H7/p6 | interference | 35 µm interference | 1 µm interference | |
| H7/r6 | interference | 41 µm interference | 7 µm interference |
These are functional starting points, not automatic design approval. Hole-basis is usually more economical because standard tooling can establish the hole while the shaft is adjusted to obtain the fit.
Already know four limit sizes? Check the resulting fit
Fit from entered limits
Classification
clearance fit
Minimum clearance
0.007 mm
Maximum clearance
0.041 mm
Hole / shaft width
0.021 / 0.013 mm
Calculated only from the limits you supplied; no standard-conformance claim.
Quick use
How to use this calculator
- Choose whether the drawing specifies a hole or shaft and enter its nominal diameter.
- Select the tolerance position letter and tolerance grade separately.
- Read the exact limits and midpoint, then check the recommended mating component and resulting fit.
Limits
Assumptions
- ISO 286-1/-2:2010 reference implementation
- Classes available in the attributed isofits 1.0 dataset, >3–400 mm
- Nominal dimensions interpreted at 20 °C
- Functional recommendations are starting points, not design approval
Provenance
Versioned reference data
Supported limits use dataset iso286-isofits-reference 2.0.0, based on the MIT-licensed isofits 1.0 implementation ↗. Dimvo checks grade widths, known answers and size boundaries. It is a reference implementation for ISO 286-1/-2:2010 ↗, not an official standards publication.
Common questions
Frequently asked questions
What does H7/g6 mean?
H7 is the hole tolerance zone and g6 is the shaft tolerance zone. The capital letter identifies the hole, the lowercase letter identifies the shaft, and the number is the tolerance grade.
Is H7/g6 a clearance fit?
Within the supported ISO 286 reference range, H7/g6 is a clearance fit. The exact clearance changes with nominal diameter; enter the diameter to calculate both limits.
Can Dimvo recommend the mating shaft for an H7 hole?
Yes. Keep H7 selected, choose the required function, and Dimvo fills a common mating shaft. You can change either class and still see the exact resulting limits.
What is the difference between hole-basis and shaft-basis fits?
Hole-basis keeps the H hole at the basic-size boundary and varies the shaft. Shaft-basis keeps an h shaft fixed and varies the hole. Hole-basis is generally the more economical starting point with standard hole-making tools.