Slip fit chart
Common clearance (slip and running) fits for parts that must move or assemble freely. Unlike a press fit, a clearance fit always leaves a gap, sized to let parts slide, turn, or come apart while still locating them.
ISO clearance fits (hole basis)
| Fit | Type | Use |
|---|---|---|
| H7/h6 | Locational clearance | Snug slip fit, assembles by hand, no perceptible play |
| H7/g6 | Sliding | Slides and turns freely with minimal clearance |
| H7/f7 | Close running | Running fit for moderate speed and good lubrication |
| H7/e8 | Loose running | Generous clearance for higher speed or temperature |
| H7/d9 | Free running | Large clearance, tolerates dirt and rough running |
Inch running clearance classes (ANSI RC)
| Class | Type | Use |
|---|---|---|
| RC1 | Close sliding | Accurate location with no perceptible play |
| RC2 | Sliding | Moves and turns freely with slight clearance |
| RC3 | Precision running | Light loads and low speeds, precise |
| RC4 to RC6 | Running | Moderate to higher speeds and loads |
| RC7 | Free running | Large clearance for wide temperature swings |
| RC8 to RC9 | Loose running | Commercial tolerances, tolerant of dirt |
Clearance fits leave the shaft smaller than the hole. A tight slip fit like H7/h6 locates parts precisely yet still comes apart by hand, while looser running fits add clearance so a shaft can spin freely without binding as it warms and expands. Pick the closest fit that gives the motion and precision the part needs.
Need an interference or bearing fit instead?
See the Press Fit Chart for interference fits, or the Bearing Fits Chart for bearings.
Slip fits vs press fits
A slip or clearance fit leaves a gap so parts move or separate easily; a press fit makes the shaft larger than the hole so they lock together. The same H7 hole pairs with a small shaft (g6, f7) for clearance or a large shaft (p6, s6) for interference. Choosing the shaft tolerance is what sets whether parts slide or grip.
Choosing a running fit
For a shaft that must rotate, the clearance has to allow for a lubricant film and for thermal expansion as it heats. A close running fit (H7/f7) suits moderate speeds with good oil; faster or hotter running needs the extra clearance of a loose fit (H7/e8 or d9) to avoid seizing. Too much clearance, though, lets the shaft wobble.
FAQ
What is a slip fit?
A clearance fit where the shaft is slightly smaller than the hole, so parts assemble and come apart by hand while still located accurately. H7/h6 is a typical snug slip fit.
What is the difference between a slip fit and a press fit?
A slip fit leaves a gap so parts move or separate freely; a press fit has interference so parts are forced together and stay locked.
Which fit lets a shaft rotate freely?
A running clearance fit such as H7/g6 or H7/f7, which leaves room for an oil film and thermal expansion so the shaft turns without binding.