PREFERRED FITS AND TOLERANCES CHARTS
Preferred fits and tolerance table for hole and shaft basis systems which are given in ISO 286-1 (2010) and ANSI B4.2-1978 standards. The usage of these tolerances is advised for economic reasons.
| ISO Symbol | Description | |
Hole Basis | Shaft Basis | ||
Clearance Fits | H11/c11 | C11/h11 | Loose running fit for wide commercial tolerances or allowances on external members. |
H9/d9 | D9/h9 | Free running fit not for use where accuracy is essential, but good for large temperature variations, high running speeds, or heavy journal pressures. | |
H8/f7 | F8/h7 | Close running fit for running on accurate machines and for accurate location at moderate speeds and journal pressures. | |
H7/g6 | G7/h6 | Sliding fit not intended to run freely, but to move and turn freely and locate accurately. | |
H7/h6 | H7/h6 | Locational clearance fit provides snug fit for locating stationary parts; but can be freely assembled and disassembled. | |
Transition Fits | H7/k6 | K7/h6 | Locational transition fit for accurate location, a compromise between clearance and interference. |
H7/n6 | N7/h6 | Locational transition fit for more accurate location where greater interference is permissible. | |
Interference Fits | H7/p6 | P7/h6 | Locational interference fit for parts requiring rigidity and alignment with prime accuracy of location but without special bore pressure requirements. |
H7/s6 | S7/h6 | Medium drive fit for ordinary steel parts or shrink fits on light sections, the tightest fit usable with cast iron. | |
H7/u6 | U7/h6 | Force fit suitable for parts which can be highly stressed or for shrink fits where the heavy pressing forces required are impractical. | |
Preferred fits table (ANSI B4.2-1978)
Basic | Tolerance classes for shafts | |||||||||||||||||
Clearance Fits | Transition Fits | Interference Fits | ||||||||||||||||
H6 |
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| g5 | h5 | js5 | k5 | m5 |
| n5 | p5 |
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H7 |
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| f6 | g6 | h6 | js6 | k6 | m6 | n6 |
| p6 | r6 | s6 | t6 | u6 | x6 |
H8 |
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| e7 | f7 |
| h7 | js7 | k7 | m7 |
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| s7 |
| u7 |
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| d8 | e8 | f8 |
| h8 |
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H9 |
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| d8 | e8 | f8 |
| h8 |
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H10 | b9 | c9 | d9 | e9 |
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| h9 |
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H11 | b11 | c11 | d10 |
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| h10 |
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Preferable fits of the hole-basis system (ISO 286-1:2010)
Basic | Tolerance classes for holes | |||||||||||||||||
Clearance Fits | Transition Fits | Interference Fits | ||||||||||||||||
h5 |
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| G6 | H6 | JS6 | K6 | M6 |
| N6 | P6 |
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h6 |
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| F7 | G7 | H7 | JS7 | K7 | M7 | N7 |
| P7 | R7 | S7 | T7 | U7 | X7 |
h7 |
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| E8 | F8 |
| H8 |
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h8 |
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| D9 | E9 | F9 |
| H9 |
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h9 |
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| E8 | F8 |
| H8 |
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| D9 | E9 | F9 |
| H9 |
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B11 | C10 | D10 |
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| H10 |
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Preferable fits of the shaft-basis system (ISO 286-1:2010)
Note: For economic reasons, the first choice for a fit should, whenever possible, be made from the tolerance classes shown with green color.