Tolerance & Fit Calculator
Hole and shaft limits, clearance and interference to AS 1654 (ISO 286) — for fits like H7/g6, H7/p6 and K7/h6.
Limits & Fits
AS 1654.1 / AS 1654.2 — nominal sizes up to 500 mm.
Hole
Shaft
Fit
Tolerance zones (µm from nominal)
Common Fits
Preferred hole-basis fits, calculated for your nominal size. Select one to load it.
| Fit | Type | Clearance (+) / interference (−) | Typical use | Load |
|---|
Standard Tolerance Grades
IT values for your nominal size, in µm.
Limits & Fits Guide
How the AS 1654 / ISO 286 system works.
The Standard
AS 1654.1 · AS 1654.2AS 1654.1–1995 (bases) and AS 1654.2–1995 (tables) are identical to ISO 286-1 and ISO 286-2:1988. This calculator uses those tables up to 500 mm.
Tolerance Class
H7 · g6The letter sets where the zone sits relative to the nominal size (fundamental deviation). The number is the IT grade — how wide the zone is.
Holes vs Shafts
CAPITALS · lowercaseCapital letters are holes (internal features), lowercase are shafts (external). H and h have one limit exactly on the nominal size.
Hole-Basis Fits
H7/…Keep the hole at H and change the shaft to get the fit. Most common, because reamers and plug gauges for H holes are standard tooling.
Fit Types
clearance · transition · interferenceClearance always has a gap. Interference always needs force or heat to assemble. Transition can be either, depending on the actual parts.
Choosing a Grade
IT5–IT7 precise · IT8–IT11 generalIT01–IT4 for gauges, IT5–IT12 for fits between parts, IT12–IT18 for non-fitting features and stock material.
Size Ranges
over 18 up to 30 mmValues change in steps. A size on a boundary (e.g. exactly 30 mm) belongs to the lower range.
Check the Standard
critical workValues follow the published tables, but for contracts, inspection or safety-critical parts always confirm against your copy of AS 1654.
Why FitGauge?
FitGauge is a fast, lightweight limits-and-fits calculator for mechanical designers, drafters, machinists and engineers working to Australian Standards — no more flipping through tables.
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