{
  "id": "iso-286",
  "title": "ISO 286 limits & fits — IT grades and fundamental deviations",
  "url": "https://nxtolerance.com/data/iso-286.json",
  "page": "https://nxtolerance.com/tools/iso-286-fit-calculator/",
  "source": {
    "name": "Engineering tolerance standards reference data",
    "publisher": "SuperNX / nxtolerance.com",
    "standards": "ISO 286-1:2010 (tolerance grades & fundamental deviations), ISO 286-2:2010 (limit deviations)",
    "note": "Values compiled from the published standard tables and cross-checked against multiple independent public references; see the verification log in the source repository.",
    "method": "itGrades = published Table 1 values (µm). shaft letters: fundamental deviation per steps [lo,hi,value] — (lo,hi] mm; dev tells which zone edge it is, the other edge is deviation ∓ IT. js = ±IT/2; k valid for grades 4–7 only (0 otherwise). holes: H ⇒ EI=0/ES=+IT; JS ⇒ ±IT/2; E/F/G ⇒ EI = −es of same-letter shaft."
  },
  "units": {
    "deviations": "µm",
    "nominal": "mm"
  },
  "bands": "over lo up to and including hi (Ø30 is in the 18–30 band)",
  "data": {
    "steps": [
      [
        0,
        3
      ],
      [
        3,
        6
      ],
      [
        6,
        10
      ],
      [
        10,
        18
      ],
      [
        18,
        30
      ],
      [
        30,
        50
      ],
      [
        50,
        80
      ],
      [
        80,
        120
      ],
      [
        120,
        180
      ],
      [
        180,
        250
      ],
      [
        250,
        315
      ],
      [
        315,
        400
      ],
      [
        400,
        500
      ]
    ],
    "itGrades": {
      "IT5": [
        4,
        5,
        6,
        8,
        9,
        11,
        13,
        15,
        18,
        20,
        23,
        25,
        27
      ],
      "IT6": [
        6,
        8,
        9,
        11,
        13,
        16,
        19,
        22,
        25,
        29,
        32,
        36,
        40
      ],
      "IT7": [
        10,
        12,
        15,
        18,
        21,
        25,
        30,
        35,
        40,
        46,
        52,
        57,
        63
      ],
      "IT8": [
        14,
        18,
        22,
        27,
        33,
        39,
        46,
        54,
        63,
        72,
        81,
        89,
        97
      ],
      "IT9": [
        25,
        30,
        36,
        43,
        52,
        62,
        74,
        87,
        100,
        115,
        130,
        140,
        155
      ],
      "IT10": [
        40,
        48,
        58,
        70,
        84,
        100,
        120,
        140,
        160,
        185,
        210,
        230,
        250
      ],
      "IT11": [
        60,
        75,
        90,
        110,
        130,
        160,
        190,
        220,
        250,
        290,
        320,
        360,
        400
      ],
      "IT12": [
        100,
        120,
        150,
        180,
        210,
        250,
        300,
        350,
        400,
        460,
        520,
        570,
        630
      ]
    },
    "shaft": {
      "e": {
        "dev": "es",
        "steps": [
          [
            0,
            3,
            -14
          ],
          [
            3,
            6,
            -20
          ],
          [
            6,
            10,
            -25
          ],
          [
            10,
            18,
            -32
          ],
          [
            18,
            30,
            -40
          ],
          [
            30,
            50,
            -50
          ],
          [
            50,
            80,
            -60
          ],
          [
            80,
            120,
            -72
          ],
          [
            120,
            180,
            -85
          ],
          [
            180,
            250,
            -100
          ],
          [
            250,
            315,
            -110
          ],
          [
            315,
            400,
            -125
          ],
          [
            400,
            500,
            -135
          ]
        ]
      },
      "f": {
        "dev": "es",
        "steps": [
          [
            0,
            3,
            -6
          ],
          [
            3,
            6,
            -10
          ],
          [
            6,
            10,
            -13
          ],
          [
            10,
            18,
            -16
          ],
          [
            18,
            30,
            -20
          ],
          [
            30,
            50,
            -25
          ],
          [
            50,
            80,
            -30
          ],
          [
            80,
            120,
            -36
          ],
          [
            120,
            180,
            -43
          ],
          [
            180,
            250,
            -50
          ],
          [
            250,
            315,
            -56
          ],
          [
            315,
            400,
            -62
          ],
          [
            400,
            500,
            -68
          ]
        ]
      },
      "g": {
        "dev": "es",
        "steps": [
          [
            0,
            3,
            -2
          ],
          [
            3,
            6,
            -4
          ],
          [
            6,
            10,
            -5
          ],
          [
            10,
            18,
            -6
          ],
          [
            18,
            30,
            -7
          ],
          [
            30,
            50,
            -9
          ],
          [
            50,
            80,
            -10
          ],
          [
            80,
            120,
            -12
          ],
          [
            120,
            180,
            -14
          ],
          [
            180,
            250,
            -15
          ],
          [
            250,
            315,
            -17
          ],
          [
            315,
            400,
            -18
          ],
          [
            400,
            500,
            -20
          ]
        ]
      },
      "h": {
        "dev": "es",
        "steps": [
          [
            0,
            500,
            0
          ]
        ]
      },
      "js": {
        "symmetric": true
      },
      "k": {
        "dev": "ei",
        "onlyGrades": [
          4,
          7
        ],
        "steps": [
          [
            0,
            3,
            0
          ],
          [
            3,
            6,
            1
          ],
          [
            6,
            10,
            1
          ],
          [
            10,
            18,
            1
          ],
          [
            18,
            30,
            2
          ],
          [
            30,
            50,
            2
          ],
          [
            50,
            80,
            2
          ],
          [
            80,
            120,
            3
          ],
          [
            120,
            180,
            3
          ],
          [
            180,
            250,
            4
          ],
          [
            250,
            315,
            4
          ],
          [
            315,
            400,
            4
          ],
          [
            400,
            500,
            5
          ]
        ]
      },
      "m": {
        "dev": "ei",
        "steps": [
          [
            0,
            3,
            2
          ],
          [
            3,
            6,
            4
          ],
          [
            6,
            10,
            6
          ],
          [
            10,
            18,
            7
          ],
          [
            18,
            30,
            8
          ],
          [
            30,
            50,
            9
          ],
          [
            50,
            80,
            11
          ],
          [
            80,
            120,
            13
          ],
          [
            120,
            180,
            15
          ],
          [
            180,
            250,
            17
          ],
          [
            250,
            315,
            20
          ],
          [
            315,
            400,
            21
          ],
          [
            400,
            500,
            23
          ]
        ]
      },
      "n": {
        "dev": "ei",
        "steps": [
          [
            0,
            3,
            4
          ],
          [
            3,
            6,
            8
          ],
          [
            6,
            10,
            10
          ],
          [
            10,
            18,
            12
          ],
          [
            18,
            30,
            15
          ],
          [
            30,
            50,
            17
          ],
          [
            50,
            80,
            20
          ],
          [
            80,
            120,
            23
          ],
          [
            120,
            180,
            27
          ],
          [
            180,
            250,
            31
          ],
          [
            250,
            315,
            34
          ],
          [
            315,
            400,
            37
          ],
          [
            400,
            500,
            40
          ]
        ]
      },
      "p": {
        "dev": "ei",
        "steps": [
          [
            0,
            3,
            6
          ],
          [
            3,
            6,
            12
          ],
          [
            6,
            10,
            15
          ],
          [
            10,
            18,
            18
          ],
          [
            18,
            30,
            22
          ],
          [
            30,
            50,
            26
          ],
          [
            50,
            80,
            32
          ],
          [
            80,
            120,
            37
          ],
          [
            120,
            180,
            43
          ],
          [
            180,
            250,
            50
          ],
          [
            250,
            315,
            56
          ],
          [
            315,
            400,
            62
          ],
          [
            400,
            500,
            68
          ]
        ]
      },
      "r": {
        "dev": "ei",
        "steps": [
          [
            0,
            3,
            10
          ],
          [
            3,
            6,
            15
          ],
          [
            6,
            10,
            19
          ],
          [
            10,
            18,
            23
          ],
          [
            18,
            30,
            28
          ],
          [
            30,
            50,
            34
          ],
          [
            50,
            65,
            41
          ],
          [
            65,
            80,
            43
          ],
          [
            80,
            100,
            51
          ],
          [
            100,
            120,
            54
          ],
          [
            120,
            140,
            63
          ],
          [
            140,
            160,
            65
          ],
          [
            160,
            180,
            68
          ],
          [
            180,
            200,
            77
          ],
          [
            200,
            225,
            80
          ],
          [
            225,
            250,
            84
          ],
          [
            250,
            280,
            94
          ],
          [
            280,
            315,
            98
          ],
          [
            315,
            355,
            108
          ],
          [
            355,
            400,
            114
          ],
          [
            400,
            450,
            126
          ],
          [
            450,
            500,
            132
          ]
        ]
      },
      "s": {
        "dev": "ei",
        "steps": [
          [
            0,
            3,
            14
          ],
          [
            3,
            6,
            19
          ],
          [
            6,
            10,
            23
          ],
          [
            10,
            18,
            28
          ],
          [
            18,
            30,
            35
          ],
          [
            30,
            50,
            43
          ],
          [
            50,
            65,
            53
          ],
          [
            65,
            80,
            59
          ],
          [
            80,
            100,
            71
          ],
          [
            100,
            120,
            79
          ],
          [
            120,
            140,
            92
          ],
          [
            140,
            160,
            100
          ],
          [
            160,
            180,
            108
          ],
          [
            180,
            200,
            122
          ],
          [
            200,
            225,
            130
          ],
          [
            225,
            250,
            140
          ],
          [
            250,
            280,
            158
          ],
          [
            280,
            315,
            170
          ],
          [
            315,
            355,
            190
          ],
          [
            355,
            400,
            208
          ],
          [
            400,
            450,
            232
          ],
          [
            450,
            500,
            252
          ]
        ]
      }
    },
    "holes": {
      "H": {
        "rule": "EI = 0, ES = +IT"
      },
      "JS": {
        "rule": "ES = +IT/2, EI = −IT/2"
      },
      "E": {
        "rule": "EI = −es(shaft e)",
        "mirrorShaft": "e"
      },
      "F": {
        "rule": "EI = −es(shaft f)",
        "mirrorShaft": "f"
      },
      "G": {
        "rule": "EI = −es(shaft g)",
        "mirrorShaft": "g"
      }
    }
  },
  "disclaimer": "Engineering reference values for design and education — verify against the current standard revision (ISO 286-1:2010, ISO 2768-1:1989, ASME Y14.5) before issuing production drawings.",
  "license": "Standard reference data. Free to use and cite with attribution to nxtolerance.com.",
  "version": "2026-10-07"
}