Creating Arc Dimensions You can dimension the true length of the arc. The default dimension type for an arc is radius. You only need to select the arc for this dimension type. To create arc dimensions: In an open sketch, click Smart Dimension (Dimensions/Relations toolbar) or Tools > Dimensions > Smart. Select the arc. Press Ctrl and select the two arc endpoints. Move the pointer to show the dimension preview. Set the value in the Modify dialog box and click . Click to place the dimension.Video: Dimensioning Arc Length Parent topicDimensions Related concepts Datum Feature Symbols