A limit tolerance is a form of dimensional tolerancing that specifies a tolerance range for a specific feature. Limit tolerances are also known as limit dimensioning and are an effective way to specify requirements on a blueprint. They clearly identify the tolerance range without requiring additional calculations by the blueprint reader.

## Limit tolerance symbol

There is no GD&T symbol for a limit tolerance. Per ASME Y14.5, the notation for a limit tolerance is to callout the upper and lower tolerance boundaries for a dimension. The upper end value of the tolerance range goes on top of the lower end value as shown in the examples below.

## Limit tolerance examples

## Limit tolerance vs unilateral tolerance

A unilateral tolerance lists a nominal value along with a plus or minus tolerance. Using these two values allows the blueprint reader to calculate the upper and lower ends of the tolerance range. A limit tolerance skips the calculation step and directly specifies the upper and lower end of the tolerance range. If the unilateral tolerance above was instead specified as a limit tolerance it would be 5.8-6.0.

## Limit tolerance vs bilateral tolerance

A bilateral tolerance lists a nominal value along with a plus/minus tolerance. Using these two values allows the blueprint reader to calculate the upper and lower ends of the tolerance range. A limit tolerance skips the calculation step and directly specifies the upper and lower end of the tolerance range. If the bilateral tolerance above were instead specified as a limit tolerance it would be 16.5-17.5.

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