GD&T Pro

ISO 286-1 / ISO 286-20 to 3150 mm

Limits and fits calculator

Engineering-grade ISO 286 fit analysis

Calculate hole and shaft limits, deviations, clearance, interference, fit class, application guidance, and exportable inspection data with an interactive technical visualization.

Fit type

Clearance fit

Fit class

Sliding fit

IT basis

H7 / g6

Live Fit Preview

Zero line, hole zone, shaft zone, and clearance window

-100-50050100Deviation from zero line, micronsHole H7Shaft g6Cmin +9.5 micronsCmax +50 microns

Inputs

Fit Basis Selection

Fit System Basis

Choose which component remains fixed as the standard reference

Industry Note: Hole Basis (H) is more common in manufacturing because it's cost-effective to use standard tooling for the hole and adjust the shaft on a CNC lathe.

Deviation Results

Clearance fit

Hole Limits

ES+25 microns
EI0.0 microns
Max hole50.0250 mm
Min hole50.0000 mm

Shaft Limits

es-9.5 microns
ei-25 microns
Max shaft49.9905 mm
Min shaft49.9749 mm

Minimum clearance

0.0095 mm

Maximum clearance

0.0501 mm

Maximum interference

0.0000 mm

Tolerance unit

1.561 microns

Tolerance Zones & Deviations

Tolerance Zone Visualization

Graphical representation of hole and shaft tolerance zones relative to nominal size

0HOLE H7ES: 25 µmEI: 0 µmSHAFT g6es: -9 µmei: -25 µmClearance RangeDeviation from Nominal Size (µm)

Hole Tolerance Zone

The allowable range for the hole diameter, shown in light blue with dotted pattern

Shaft Tolerance Zone

The allowable range for the shaft diameter, shown in purple with dotted pattern

Clearance Range

Gap between min hole and max shaft (min: 10, max: 50 µm)

Symbol Meanings

Symbol Definitions

ESUpper Deviation (Hole)

Maximum tolerance limit above nominal size for the hole

+21 µm

EILower Deviation (Hole)

Minimum tolerance limit below nominal size for the hole

0 µm

esUpper Deviation (Shaft)

Maximum tolerance limit above nominal size for the shaft

-7 µm

eiLower Deviation (Shaft)

Minimum tolerance limit below nominal size for the shaft

-20 µm

Comparison Chart

H7/g60.0501 mmH7/h60.0406 mmH8/f70.0913 mmH7/k60.0227 mmH7/p6-0.0164 mm

Formula Trace

Geometric mean diameter

D = sqrt(lower size step x upper size step)

38.730 mm

Standard tolerance unit

i = 0.45 cube_root(D) + 0.001D

1.561 microns

Hole limits

H7: 50 + EI/ES

50.0000 mm to 50.0250 mm

Shaft limits

g6: 50 + ei/es

49.9749 mm to 49.9905 mm

Clearance range

Cmin = Hole min - Shaft max; Cmax = Hole max - Shaft min

+9.5 microns to +50 microns

Fit Recommendation

A small reliable clearance supports accurate rotation while allowing assembly without press equipment.

Recommended standard fit

H7/g6

Ground shaft, bored housing

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ISO 286 Table Browser

Size stepIT5IT6IT7IT8IT9IT10IT11IT12IT13
Over 30 to 50 mm10.915.625.039.062.499.9156.1249.8390.3

Hole letters: A, B, C, D, E, F, G, H, JS, K, M, N, P, R, S, T, U

Shaft letters: a, b, c, d, e, f, g, h, js, k, m, n, p, r, s, t, u

Engineering Examples

Bearing Shaft Fit

H7/g6

Retains accurate rotation with a measurable running clearance and controlled service assembly.

Gearbox Assembly

H7/k6

Transition behavior improves centering while keeping the hub removable with standard shop tooling.

Piston-Cylinder Fit

H8/f7

Extra clearance supports lubrication, seal travel, and thermal expansion in reciprocating motion.

Automotive Transmission Shaft

H7/h6

The hole-basis system reduces tooling complexity while the h shaft keeps maximum material at nominal.

CNC Spindle Fit

H6/js5

A narrow symmetric shaft zone supports high repeatability and low radial error.

Coupling Fit

H7/p6

An interference band creates holding force without relying only on keys, pins, or clamp screws.