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Engineering quick reference

ISO 286 Fits & Tolerance Reference

Preferred hole-basis fits (H7/g6, H7/h6, H7/p6, H7/u6, …) with tolerance bands and fit type.

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Fit zones at a glance — drawn to scale

Drawn-to-scale ISO 286 hole-basis tolerance zones for the 6 to 10 millimeter band. Clearance: the g6 or h6 shaft zone sits at or below the H7 hole zone, so the fit is never a press. Transition: the k6 or n6 shaft zone overlaps the hole zone, so the result can be a gap or a press. Interference: the p6 or s6 shaft zone sits at or above the hole zone, so assembly is always a press. ISO 286 TOLERANCE ZONES — DEVIATIONS IN µm (0.001 mm), 6–10 mm NOMINAL BAND — DRAWN TO SCALE H7 +15 0 g6 −5 −14 h6 0 −9 GAP CLEARANCE Shaft zone at / below the hole zone — never a press. H7/g6 gap 5–29 µm · H7/h6 gap 0–24 µm H7 k6 +10 +1 n6 +19 +10 GAP OR PRESS TRANSITION Shaft zone overlaps the hole zone — gap or press. H7/k6 light tap · H7/n6 mallet — either outcome H7 p6 +24 +15 s6 +32 +23 PRESS INTERFERENCE Shaft zone at / above the hole zone — never a gap. H7/p6 press 0–24 µm · H7/s6 press 8–32 µm + − ZERO LINE — BASIC SIZE HOLE-BASIS — THE HOLE TOLERANCE IS FIXED (H7 SHOWN); THE SHAFT LETTER SETS THE FIT

Preferred hole-basis fits

Fit ISO Type Typical use
Loose running H11/c11 Clearance Linkages, lever pivots, hinge pins
Free running H9/d9 Clearance Bushings on shafts, low-precision bearings
Close running H8/f7 Clearance Spindle bearings, pilot pins, gear shafts
Sliding H7/g6 Clearance Sliding gears, drill bushings, sliding shafts
Locational clearance H7/h6 Clearance Locating shafts, dowel-pin sleeves, alignment fits
Locational transition (push) H7/k6 Transition Press-fit dowel pins (small), removable sleeves
Locational transition (heavy push) H7/n6 Transition Locating bushings, fixed dowel pins
Locational interference (light press) H7/p6 Interference Bearing inner rings, fixed bushings
Medium drive H7/s6 Interference Coupling on shafts, heavy bushings
Force fit H7/u6 Interference Permanent gear/wheel-on-shaft, heavy press-fits

■ Clearance = gap · ■ Transition = either · ■ Interference = press

Tolerance bands — 6–10 mm nominal

Class Upper (mm) Lower (mm) Role
Holes — lower limit at zero
H11 +0.090 0 Hole — loose
H9 +0.036 0 Hole — free running
H8 +0.022 0 Hole — close running
H7 +0.015 0 Hole — standard precision
Shafts — clearance (at / below zero)
h6 0 −0.009 Shaft — locational clearance
g6 −0.005 −0.014 Shaft — sliding
f7 −0.013 −0.028 Shaft — close running
d9 −0.040 −0.076 Shaft — free running
c11 −0.080 −0.170 Shaft — loose running
Shafts — transition (overlap the H7 zone)
k6 +0.010 +0.001 Shaft — push fit (transition)
n6 +0.019 +0.010 Shaft — heavy push (transition)
Shafts — interference (at / above H7 max)
p6 +0.024 +0.015 Shaft — light press (interference)
s6 +0.032 +0.023 Shaft — medium drive (interference)
u6 +0.037 +0.028 Shaft — force fit (interference)

Values in mm · + above / − below the zero line · CAPITAL = hole · lowercase = shaft

Selection rules of thumb

  • Default H7/h6 for accurate location (~80% of cases): locating sleeves, alignment & dowel-pin holes.
  • Sliding motion: drop the shaft to g6 (H7/g6) or f7 (H8/f7). Don’t use h6 for sliding parts — it binds under thermal growth.
  • Press fits: start light (H7/p6), then medium (H7/s6), then heavy (H7/u6). Beyond u6 usually needs shrink-fit.
  • k6 / n6 are transition: sometimes clearance, sometimes interference — use only when the ambiguity is intentional.
  • Size matters: a 10 mm H7 hole is +0.015; a 100 mm H7 hole is +0.035. Look up the actual band — don’t scale linearly.

Hole-basis: the hole tolerance is fixed (typ. H7/H8) and the shaft changes to set the fit. Reading example — a 10 mm H7 hole (+0.015/0) with an h6 shaft (0/−0.009) gives H7/h6: 0 to 0.024 mm clearance. The same H7 hole with p6 (+0.024/+0.015) gives H7/p6: 0 to 0.024 mm interference. For the interactive limits & fits visualizer, see the full standard fits guide.

Free engineering reference from True Precision Machining
trueprecisionmachining.com · 805-964-4545 · Buellton, CA · AS9100 / ISO 9001 / ITAR
Tolerance values are the 6–10 mm nominal band per ISO 286 — look up your actual size band for design-critical work. · September 2026