{
    "slug": "general-tolerances-iso-2768",
    "title": "ISO 2768 General Tolerances: f, m, c, v and H, K, L",
    "description": "Untoleranced dimensions are not tolerance-free: ISO 2768 tables for linear, angular and geometric tolerances in f/m/c/v and H/K/L, with grade selection rules.",
    "lang": "en",
    "tables": [
        {
            "caption": "ISO 2768-1 permissible deviations for linear dimensions (± mm, excluding chamfers)",
            "columns": [
                "Nominal size range (mm)",
                "f (fine)",
                "m (medium)",
                "c (coarse)",
                "v (very coarse)"
            ],
            "rows": [
                {
                    "Nominal size range (mm)": "0.5 up to 3",
                    "f (fine)": "±0.05",
                    "m (medium)": "±0.1",
                    "c (coarse)": "±0.2",
                    "v (very coarse)": "—"
                },
                {
                    "Nominal size range (mm)": "over 3 up to 6",
                    "f (fine)": "±0.05",
                    "m (medium)": "±0.1",
                    "c (coarse)": "±0.3",
                    "v (very coarse)": "±0.5"
                },
                {
                    "Nominal size range (mm)": "over 6 up to 30",
                    "f (fine)": "±0.1",
                    "m (medium)": "±0.2",
                    "c (coarse)": "±0.5",
                    "v (very coarse)": "±1"
                },
                {
                    "Nominal size range (mm)": "over 30 up to 120",
                    "f (fine)": "±0.15",
                    "m (medium)": "±0.3",
                    "c (coarse)": "±0.8",
                    "v (very coarse)": "±1.5"
                },
                {
                    "Nominal size range (mm)": "over 120 up to 400",
                    "f (fine)": "±0.2",
                    "m (medium)": "±0.5",
                    "c (coarse)": "±1.2",
                    "v (very coarse)": "±2.5"
                },
                {
                    "Nominal size range (mm)": "over 400 up to 1000",
                    "f (fine)": "±0.3",
                    "m (medium)": "±0.8",
                    "c (coarse)": "±2",
                    "v (very coarse)": "±4"
                },
                {
                    "Nominal size range (mm)": "over 1000 up to 2000",
                    "f (fine)": "±0.5",
                    "m (medium)": "±1.2",
                    "c (coarse)": "±3",
                    "v (very coarse)": "±6"
                },
                {
                    "Nominal size range (mm)": "over 2000 up to 4000",
                    "f (fine)": "—",
                    "m (medium)": "±2",
                    "c (coarse)": "±4",
                    "v (very coarse)": "±8"
                }
            ]
        },
        {
            "caption": "What tolerance applies when a drawing dimension has none?",
            "columns": [
                "Step",
                "Item",
                "Value"
            ],
            "rows": [
                {
                    "Step": "1",
                    "Item": "Dimension type",
                    "Value": "linear (Ø50 outer diameter) — ISO 2768-1 table"
                },
                {
                    "Step": "2",
                    "Item": "Band",
                    "Value": "50 falls in over 30 up to 120"
                },
                {
                    "Step": "3",
                    "Item": "m-grade deviation",
                    "Value": "±0.3 mm"
                },
                {
                    "Step": "4",
                    "Item": "Acceptance range",
                    "Value": "49.700–50.300 mm (band 0.6)"
                },
                {
                    "Step": "5",
                    "Item": "K-grade roundness",
                    "Value": "min(diameter tolerance 0.6, K run-out 0.2) = 0.2 mm; straightness of a 50 mm generator line (over 30–100) = 0.2 mm"
                },
                {
                    "Step": "6",
                    "Item": "Verdict",
                    "Value": "Ø in 49.700–50.300 with run-out ≤ 0.2 mm against the datum axis = conforming"
                }
            ]
        },
        {
            "caption": "Are GB/T 1804 and ISO 2768-1 the same numbers?",
            "columns": [
                "Standard",
                "Maps to",
                "Grades",
                "Values vs ISO 2768",
                "Naming / structure"
            ],
            "rows": [
                {
                    "Standard": "ISO 2768-1:1989 / -2:1989",
                    "Maps to": "—",
                    "Grades": "f m c v / H K L",
                    "Values vs ISO 2768": "baseline",
                    "Naming / structure": "the de-facto referenced editions"
                },
                {
                    "Standard": "DIN ISO 2768-1/-2:1991",
                    "Maps to": "direct adoption",
                    "Grades": "f m c v / H K L",
                    "Values vs ISO 2768": "identical",
                    "Naming / structure": "old DIN 7168 superseded by DIN ISO 2768"
                },
                {
                    "Standard": "EN 22768-1 / BS EN 22768-1",
                    "Maps to": "adopts ISO 2768-1",
                    "Grades": "f m c v",
                    "Values vs ISO 2768": "identical",
                    "Naming / structure": "—"
                },
                {
                    "Standard": "GB/T 1804-2000",
                    "Maps to": "eqv ISO 2768-1:1989",
                    "Grades": "f / m / c / v — same letters with Chinese grade names",
                    "Values vs ISO 2768": "identical",
                    "Naming / structure": "letters identical, names translated in the Chinese standard"
                },
                {
                    "Standard": "GB/T 1184-1996",
                    "Maps to": "eqv ISO 2768-2:1989 (untoleranced part)",
                    "Grades": "H K L",
                    "Values vs ISO 2768": "identical",
                    "Naming / structure": "also contains indicated-tolerance tables (not this page's scope)"
                },
                {
                    "Standard": "JIS B 0405-1991",
                    "Maps to": "adopts ISO 2768-1:1989",
                    "Grades": "f m c v",
                    "Values vs ISO 2768": "identical",
                    "Naming / structure": "Japan splits the parts across two standard numbers"
                },
                {
                    "Standard": "JIS B 0419-1991",
                    "Maps to": "corresponds to ISO 2768-2:1989",
                    "Grades": "H K L",
                    "Values vs ISO 2768": "identical",
                    "Naming / structure": "the split is the only structural difference from ISO"
                }
            ]
        },
        {
            "caption": "f, m, c or v — which grade is the CNC default?",
            "columns": [
                "Band (mm)",
                "m (± mm)",
                "c (± mm)",
                "c / m"
            ],
            "rows": [
                {
                    "Band (mm)": "0.5 up to 3",
                    "m (± mm)": "0.1",
                    "c (± mm)": "0.2",
                    "c / m": "2.0"
                },
                {
                    "Band (mm)": "over 3 up to 6",
                    "m (± mm)": "0.1",
                    "c (± mm)": "0.3",
                    "c / m": "3.0"
                },
                {
                    "Band (mm)": "over 6 up to 30",
                    "m (± mm)": "0.2",
                    "c (± mm)": "0.5",
                    "c / m": "2.5"
                },
                {
                    "Band (mm)": "over 30 up to 120",
                    "m (± mm)": "0.3",
                    "c (± mm)": "0.8",
                    "c / m": "2.7"
                },
                {
                    "Band (mm)": "over 120 up to 400",
                    "m (± mm)": "0.5",
                    "c (± mm)": "1.2",
                    "c / m": "2.4"
                },
                {
                    "Band (mm)": "over 400 up to 1000",
                    "m (± mm)": "0.8",
                    "c (± mm)": "2",
                    "c / m": "2.5"
                },
                {
                    "Band (mm)": "over 1000 up to 2000",
                    "m (± mm)": "1.2",
                    "c (± mm)": "3",
                    "c / m": "2.5"
                },
                {
                    "Band (mm)": "over 2000 up to 4000",
                    "m (± mm)": "2",
                    "c (± mm)": "4",
                    "c / m": "2.0"
                }
            ]
        },
        {
            "caption": "How much looser is ISO 2768-c than -m at 50 mm?",
            "columns": [
                "Step",
                "Item",
                "Value"
            ],
            "rows": [
                {
                    "Step": "1",
                    "Item": "Dimension type",
                    "Value": "angle 30° untoleranced, grade c — key off the shorter side"
                },
                {
                    "Step": "2",
                    "Item": "Sides",
                    "Value": "60 mm and 8 mm → shorter side 8 mm → up to 10 band"
                },
                {
                    "Step": "3",
                    "Item": "c-grade angular deviation",
                    "Value": "±1°30′ → 28°30′–31°30′"
                },
                {
                    "Step": "4",
                    "Item": "Linear offset of the short end",
                    "Value": "8 × tan 1.5° ≈ ±0.21 mm"
                },
                {
                    "Step": "5",
                    "Item": "Same angle read on the 60 mm side",
                    "Value": "over 50–120 band → c = ±0°30′ — the shorter side governs, not the longer"
                },
                {
                    "Step": "6",
                    "Item": "If the drawing were m grade",
                    "Value": "up to 10 band = ±1°, 0°30′ tighter than c"
                }
            ]
        },
        {
            "caption": "What does the K in ISO 2768-mK control?",
            "columns": [
                "Nominal length (mm)",
                "H",
                "K",
                "L"
            ],
            "rows": [
                {
                    "Nominal length (mm)": "up to 10",
                    "H": "0.02",
                    "K": "0.05",
                    "L": "0.1"
                },
                {
                    "Nominal length (mm)": "over 10 up to 30",
                    "H": "0.05",
                    "K": "0.1",
                    "L": "0.2"
                },
                {
                    "Nominal length (mm)": "over 30 up to 100",
                    "H": "0.1",
                    "K": "0.2",
                    "L": "0.4"
                },
                {
                    "Nominal length (mm)": "over 100 up to 300",
                    "H": "0.2",
                    "K": "0.4",
                    "L": "0.8"
                },
                {
                    "Nominal length (mm)": "over 300 up to 1000",
                    "H": "0.3",
                    "K": "0.6",
                    "L": "1.2"
                },
                {
                    "Nominal length (mm)": "over 1000 up to 3000",
                    "H": "0.4",
                    "K": "0.8",
                    "L": "1.6"
                }
            ]
        },
        {
            "caption": "What perpendicularity applies untoleranced under K?",
            "columns": [
                "Shorter side (mm)",
                "H",
                "K",
                "L"
            ],
            "rows": [
                {
                    "Shorter side (mm)": "up to 100",
                    "H": "0.2",
                    "K": "0.4",
                    "L": "0.6"
                },
                {
                    "Shorter side (mm)": "over 100 up to 300",
                    "H": "0.3",
                    "K": "0.6",
                    "L": "1"
                },
                {
                    "Shorter side (mm)": "over 300 up to 1000",
                    "H": "0.4",
                    "K": "0.8",
                    "L": "1.5"
                },
                {
                    "Shorter side (mm)": "over 1000 up to 3000",
                    "H": "0.5",
                    "K": "1",
                    "L": "2"
                }
            ]
        },
        {
            "caption": "What symmetry applies untoleranced?",
            "columns": [
                "Nominal length (mm)",
                "H",
                "K",
                "L"
            ],
            "rows": [
                {
                    "Nominal length (mm)": "up to 100",
                    "H": "0.5",
                    "K": "0.6",
                    "L": "0.6"
                },
                {
                    "Nominal length (mm)": "over 100 up to 300",
                    "H": "0.5",
                    "K": "0.6",
                    "L": "1"
                },
                {
                    "Nominal length (mm)": "over 300 up to 1000",
                    "H": "0.5",
                    "K": "0.8",
                    "L": "1.5"
                },
                {
                    "Nominal length (mm)": "over 1000 up to 3000",
                    "H": "0.5",
                    "K": "1",
                    "L": "2"
                }
            ]
        },
        {
            "caption": "What run-out applies untoleranced under K?",
            "columns": [
                "Tolerance class",
                "Run-out (mm)",
                "Status"
            ],
            "rows": [
                {
                    "Tolerance class": "H",
                    "Run-out (mm)": "0.1",
                    "Status": "three verified sources agree"
                },
                {
                    "Tolerance class": "K",
                    "Run-out (mm)": "0.2",
                    "Status": "three verified sources agree"
                },
                {
                    "Tolerance class": "L",
                    "Run-out (mm)": "0.5",
                    "Status": "three verified sources agree"
                },
                {
                    "Tolerance class": "K 0.1 / L 0.2 (circulating copy)",
                    "Run-out (mm)": "—",
                    "Status": "registered, not adopted — no verified source"
                }
            ]
        },
        {
            "caption": "How are roundness, parallelism and coaxiality handled untoleranced?",
            "columns": [
                "Item",
                "Untoleranced value rule"
            ],
            "rows": [
                {
                    "Item": "Roundness",
                    "Untoleranced value rule": "equals the element's diameter tolerance, capped at the radial run-out value (K: 0.2)"
                },
                {
                    "Item": "Cylindricity",
                    "Untoleranced value rule": "not separately specified — controlled via roundness, straightness and parallelism"
                },
                {
                    "Item": "Parallelism",
                    "Untoleranced value rule": "the larger of the size tolerance and the straightness/flatness value"
                },
                {
                    "Item": "Coaxiality",
                    "Untoleranced value rule": "not specified; at the limit, equal to the radial run-out value"
                },
                {
                    "Item": "Total run-out",
                    "Untoleranced value rule": "not specified — controlled by form and position tolerances"
                },
                {
                    "Item": "Angularity (inclination)",
                    "Untoleranced value rule": "no separate value — governed by the angular tolerance and the straightness/flatness values"
                }
            ]
        },
        {
            "caption": "What is the untoleranced tolerance on a 30° chamfer?",
            "columns": [
                "Shorter side (mm)",
                "f",
                "m",
                "c",
                "v"
            ],
            "rows": [
                {
                    "Shorter side (mm)": "up to 10",
                    "f": "±1°",
                    "m": "±1°",
                    "c": "±1°30′",
                    "v": "±3°"
                },
                {
                    "Shorter side (mm)": "over 10 up to 50",
                    "f": "±0°30′",
                    "m": "±0°30′",
                    "c": "±1°",
                    "v": "±2°"
                },
                {
                    "Shorter side (mm)": "over 50 up to 120",
                    "f": "±0°20′",
                    "m": "±0°20′",
                    "c": "±0°30′",
                    "v": "±1°"
                },
                {
                    "Shorter side (mm)": "over 120 up to 400",
                    "f": "±0°10′",
                    "m": "±0°10′",
                    "c": "±0°15′",
                    "v": "±0°30′"
                },
                {
                    "Shorter side (mm)": "over 400",
                    "f": "±0°5′",
                    "m": "±0°5′",
                    "c": "±0°10′",
                    "v": "±0°20′"
                }
            ]
        },
        {
            "caption": "What tolerance applies to untoleranced radii and chamfer heights?",
            "columns": [
                "Nominal size range (mm)",
                "f",
                "m",
                "c",
                "v"
            ],
            "rows": [
                {
                    "Nominal size range (mm)": "0.5 up to 3",
                    "f": "±0.2",
                    "m": "±0.2",
                    "c": "±0.4",
                    "v": "±0.4"
                },
                {
                    "Nominal size range (mm)": "over 3 up to 6",
                    "f": "±0.5",
                    "m": "±0.5",
                    "c": "±1",
                    "v": "±1"
                },
                {
                    "Nominal size range (mm)": "over 6",
                    "f": "±1",
                    "m": "±1",
                    "c": "±2",
                    "v": "±2"
                }
            ]
        },
        {
            "caption": "Is a part outside general tolerances automatically rejected?",
            "columns": [
                "Standard status",
                "State",
                "Note"
            ],
            "rows": [
                {
                    "Standard status": "ISO 2768-1:1989",
                    "State": "in force in practice",
                    "Note": "GB/T 1804, DIN ISO 2768 and JIS B 0405/0419 all key off it; still the referenced edition"
                },
                {
                    "Standard status": "ISO 2768-2:1989",
                    "State": "withdrawn (2021-02) — superseded by ISO 22081:2021",
                    "Note": "ISO 22081 (GPS — general geometrical specifications) carries the same H/K/L untoleranced values; this page's geometry tables remain valid under either"
                },
                {
                    "Standard status": "Integrated new ISO 2768 (linear + angular)",
                    "State": "under publication",
                    "Note": "re-verify this page's tables once the integrated edition goes to publication-complete status"
                }
            ]
        },
        {
            "caption": "Does ISO 2768 override an individually stated tolerance?",
            "columns": [
                "Level",
                "Rule"
            ],
            "rows": [
                {
                    "Level": "1 — individually indicated tolerances",
                    "Rule": "ISO 286 fit zones, GD&T frames, explicit ±: always override the general band"
                },
                {
                    "Level": "2 — invoked general tolerance",
                    "Rule": "ISO 2768 grade applies to every dimension without an individual tolerance"
                },
                {
                    "Level": "3 — good workmanship",
                    "Rule": "ISO 8015 independence plus process capability govern acceptance; out-of-general-band is not automatic scrap but is not license either"
                }
            ]
        },
        {
            "caption": "How is ISO 2768 indicated on a drawing?",
            "columns": [
                "Drawing note",
                "What it invokes"
            ],
            "rows": [
                {
                    "Drawing note": "ISO 2768-mK",
                    "What it invokes": "linear + angular per m, geometry per K — the common full invocation"
                },
                {
                    "Drawing note": "ISO 2768-m",
                    "What it invokes": "sizes only; no geometry grade invoked"
                },
                {
                    "Drawing note": "ISO 2768-K",
                    "What it invokes": "geometry only; sizes stay on the drawing"
                },
                {
                    "Drawing note": "nothing stated",
                    "What it invokes": "no general tolerance exists — confirm the grade before quoting"
                }
            ]
        },
        {
            "caption": "JIS B 0405 vs ISO 2768-1 — any mapping gap?",
            "columns": [
                "JIS standard",
                "Covers",
                "Grades",
                "Values"
            ],
            "rows": [
                {
                    "JIS standard": "JIS B 0405-1991",
                    "Covers": "linear + angular (ISO 2768-1)",
                    "Grades": "f m c v",
                    "Values": "identical"
                },
                {
                    "JIS standard": "JIS B 0419-1991",
                    "Covers": "geometry (ISO 2768-2)",
                    "Grades": "H K L",
                    "Values": "identical"
                }
            ]
        },
        {
            "caption": "What flatness applies to an untoleranced 200 mm face under K?",
            "columns": [
                "Conflict point",
                "Adopted value",
                "Variant seen",
                "Handling"
            ],
            "rows": [
                {
                    "Conflict point": "v grade, 1000–2000 linear band",
                    "Adopted value": "±6",
                    "Variant seen": "±5",
                    "Handling": "three sources vs one; ±6 also fits the c×2 progression — ±5 registered, not deleted"
                },
                {
                    "Conflict point": "straightness H, over 10–30",
                    "Adopted value": "0.05",
                    "Variant seen": "0.06",
                    "Handling": "three sources agree; 0.06 is a single-page OCR transcription"
                },
                {
                    "Conflict point": "perpendicularity L, up to 100",
                    "Adopted value": "0.6",
                    "Variant seen": "0.5",
                    "Handling": "three sources agree; the 0.5 page carries the same transcription defect as the ±5 above"
                },
                {
                    "Conflict point": "run-out class values",
                    "Adopted value": "H 0.1 / K 0.2 / L 0.5",
                    "Variant seen": "circulating K 0.1 / L 0.2",
                    "Handling": "no verified source behind the circulating variant"
                }
            ]
        },
        {
            "caption": "Sheet-metal bracket — quote m or c?",
            "columns": [
                "Scenario",
                "Default grade",
                "Rationale and exceptions"
            ],
            "rows": [
                {
                    "Scenario": "CNC turning/milling/drilling, structural parts",
                    "Default grade": "ISO 2768-mK",
                    "Rationale and exceptions": "industry-standard default: m linear (±0.1 to ±1.2 across 0.5–2000) + K geometry (run-out 0.2)"
                },
                {
                    "Scenario": "Fitting surfaces / bearing seats / seal faces",
                    "Default grade": "never general tolerance",
                    "Rationale and exceptions": "must be individually indicated (ISO 286 or GD&T); the m band ±0.3 is useless against an H7 +0.025/0"
                },
                {
                    "Scenario": "Sheet-metal bending / laser cutting (1–6 mm)",
                    "Default grade": "ISO 2768-c",
                    "Rationale and exceptions": "springback and thickness fluctuation; c ±1.2 is the quotable band"
                },
                {
                    "Scenario": "Large welded frames",
                    "Default grade": "ISO 2768-v or ISO 13920",
                    "Rationale and exceptions": "welded structures fit ISO 13920 better; v is the frame convention"
                },
                {
                    "Scenario": "Thin-walled, distortion-prone cut parts",
                    "Default grade": "usually c",
                    "Rationale and exceptions": "quote c and state it — honest quoting beats an m band nobody can hold"
                },
                {
                    "Scenario": "Drawing with no tolerance statement at all",
                    "Default grade": "none — confirm",
                    "Rationale and exceptions": "ISO 2768 does not self-activate; price with an mK assumption, state the assumption, get the grade confirmed"
                },
                {
                    "Scenario": "Plastic / 3D-printed parts",
                    "Default grade": "not this table",
                    "Rationale and exceptions": "shrinkage and process govern; ISO 2768 covers metal cutting and sheet metal only"
                }
            ]
        },
        {
            "caption": "What is the smallest band ISO 2768-1 covers?",
            "columns": [
                "Item",
                "Value"
            ],
            "rows": [
                {
                    "Item": "Smallest linear band",
                    "Value": "0.5 up to 3 mm"
                },
                {
                    "Item": "f / m / c deviations there",
                    "Value": "±0.05 / ±0.1 / ±0.2"
                },
                {
                    "Item": "Below 0.5 mm",
                    "Value": "tolerance must be stated next to the dimension"
                },
                {
                    "Item": "Radii/chamfer heights, 0.5–3 mm",
                    "Value": "±0.2 (f = m), ±0.4 (c = v)"
                }
            ]
        }
    ]
}