Linear dimensions
Lengths, widths, heights, diameters and similar dimensions from 0.5 to 4,000 mm, where the selected class provides a value.
ENGINEERING TOOL · METRIC & DECIMAL INCH
ISO 2768 and decimal-inch general tolerance calculator
Look up ISO 2768-1 metric tolerances for linear dimensions, external radii, chamfer heights and angles—or calculate decimal-inch limits from the tolerance printed in a drawing title block.Two systems kept separateISO metric tables or drawing-defined inch rules.
METRIC & DECIMAL-INCH LOOKUP
Calculate an unspecified drawing tolerance.
Enter a basic size from 0.5 to 4,000 mm. The selected class applies only when the drawing invokes ISO 2768-1.
CALCULATED GENERAL TOLERANCE
50 mm · ISO 2768-m
Medium class
Permissible deviation±0.300 mm
Lower limit49.700 mm
Upper limit50.300 mm
Applicable size range>30–120 mm
A 50 mm untoleranced linear dimension under ISO 2768-m may be 49.700–50.300 mm.Reference result only. An individually stated drawing tolerance overrides the general tolerance.
WHAT THIS CALCULATOR COVERS
Complete ISO 2768-1 metric coverage plus a separate inch-drawing mode.
Broken edges
External radii and chamfer heights use their own table; they must not be calculated with the ordinary linear-dimension values.
Angular dimensions
The shorter side length selects the permissible angular deviation. Enter the nominal angle to receive its minimum and maximum.
Decimal-inch drawings
Select X.X through X.XXXX and enter the tolerance stated in the drawing title block. These values are drawing-defined, not an ISO conversion.
Standard status matters.This tool follows ISO 2768-1:1989. ISO still lists part 1 as published, with a new ISO 2768 edition under publication. ISO 2768-2:1989 is withdrawn and is intentionally not calculated here.
WORKED ISO 2768 EXAMPLES
From the title-block class to actual inspection limits.
The nominal dimension first selects the correct range, then the f, m, c or v class determines the permissible deviation.WHY THE INCH MODE ASKS FOR A SOURCE
Decimal places identify a title-block row; they do not create the tolerance value.
ISO 2768-1 REFERENCE TABLES
Check the table behind the calculation.
TABLE 1
Linear dimensions except broken edges
| Nominal size range | f — Fine | m — Medium | c — Coarse | v — Very coarse |
|---|---|---|---|---|
| 0.5–3 mm | ±0.05 mm | ±0.1 mm | ±0.2 mm | — |
| >3–6 mm | ±0.05 mm | ±0.1 mm | ±0.3 mm | ±0.5 mm |
| >6–30 mm | ±0.1 mm | ±0.2 mm | ±0.5 mm | ±1 mm |
| >30–120 mm | ±0.15 mm | ±0.3 mm | ±0.8 mm | ±1.5 mm |
| >120–400 mm | ±0.2 mm | ±0.5 mm | ±1.2 mm | ±2.5 mm |
| >400–1,000 mm | ±0.3 mm | ±0.8 mm | ±2 mm | ±4 mm |
| >1,000–2,000 mm | ±0.5 mm | ±1.2 mm | ±3 mm | ±6 mm |
| >2,000–4,000 mm | — | ±2 mm | ±4 mm | ±8 mm |
TABLE 2
External radii and chamfer heights
| Nominal size range | f — Fine | m — Medium | c — Coarse | v — Very coarse |
|---|---|---|---|---|
| 0.5–3 mm | ±0.2 mm | ±0.2 mm | ±0.4 mm | ±0.4 mm |
| >3–6 mm | ±0.5 mm | ±0.5 mm | ±1 mm | ±1 mm |
| >6 mm | ±1 mm | ±1 mm | ±2 mm | ±2 mm |
TABLE 3
Angular dimensions by shorter side length
| Shorter side length | f — Fine | m — Medium | c — Coarse | v — Very coarse |
|---|---|---|---|---|
| Up to 10 mm | ±1° | ±1° | ±1°30′ | ±3° |
| >10–50 mm | ±30′ | ±30′ | ±1° | ±2° |
| >50–120 mm | ±20′ | ±20′ | ±30′ | ±1° |
| >120–400 mm | ±10′ | ±10′ | ±15′ | ±30′ |
| >400 mm | ±5′ | ±5′ | ±10′ | ±20′ |
HOW TO APPLY THE RESULT
A general tolerance is a drawing rule, not a default for every dimension.
Confirm the drawing invokes it
Look for ISO 2768-1 and the class in the title block, general notes or applicable specification. Do not assume class m because it is common.
Use the correct dimension type
Ordinary sizes, broken edges and angles use different tables. For an angle, use the shorter side forming the angle to select the range.
Respect individual tolerances
A limit, ± tolerance, fit callout or other tolerance printed directly with the dimension overrides the general table value.
Review functional requirements
ISO 2768-1 does not by itself control surface texture, fits, geometric tolerance, coating change, inspection method or measurement uncertainty.
ISO 2768 FAQ
Common questions about unspecified drawing tolerances.
What does ISO 2768-m mean on a drawing?
The m identifies the medium general-tolerance class in ISO 2768-1. When the drawing invokes ISO 2768-m, eligible dimensions without an individual tolerance use the class-m table value for their nominal-size range. It does not replace a tolerance printed directly beside a dimension.
What is the difference between ISO 2768-f, m, c and v?
They are progressively wider general-tolerance classes: f is fine, m is medium, c is coarse and v is very coarse. The actual permissible deviation also depends on the dimension type and nominal-size range, so the class letter alone is not a numeric tolerance.
Does ISO 2768-1 cover chamfers, radii and angles?
Yes. ISO 2768-1 has separate tables for ordinary linear dimensions, external radii and chamfer heights (broken edges), and angular dimensions. Angular tolerance is selected using the length of the shorter side forming the angle.
Does a stated dimension tolerance override ISO 2768?
Yes. A tolerance stated directly with a dimension takes precedence. General tolerances are intended for eligible dimensions that do not have an individual tolerance, and only when the drawing or specification invokes the standard and class.
Is ISO 2768 the same as ISO 286 fits and tolerances?
No. ISO 2768-1 supplies general tolerances for dimensions without individual tolerance indications. ISO 286 defines tolerance zones and IT grades for features of size and fits such as H7/g6. Use the ISO 286 fits calculator when the drawing contains a letter-and-grade fit callout.
Why does this calculator not include ISO 2768-2 classes H, K and L?
ISO 2768-2:1989 was withdrawn and replaced by ISO 22081:2021. This calculator deliberately covers ISO 2768-1 dimensional tolerances only. For an older drawing marked ISO 2768-mK, verify the drawing revision and the applicable geometrical-tolerance specification with the responsible engineer.
Is there one universal ASME decimal-inch general tolerance table?
No. ASME Y14.5 establishes rules and practices for stating and interpreting dimensions and tolerances, but decimal-place values such as X.XX or X.XXX are supplied by the controlled drawing, title block, general note or governing organizational specification. The inch mode therefore requires the drawing value by default.
What is the NASA SSC inch-tolerance preset?
It is a traceable public example from NASA Stennis Space Center standard SSTD-8070-0140 A: X.X ±0.1 in, X.XX ±0.03 in, X.XXX ±0.010 in and angular X.X ±0.1°. It is not an ASME default and must not be applied to unrelated drawings unless their governing requirements explicitly use those values.
REFERENCE BASIS