Why is the dimension 'negative' in the Dimension dialog'?

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Why is the dimension 'negative' in the Dimension dialog'?

Why is my dimension negative?

Negative Dimensions.

The sign appears if the coordinate of a dimension is negative.

Generally, do not delete the sign, but edit the dimension in the normal way.

More Details


Lines have an X-Y coordinate-system.

The 0,0 of a Line is at its start-Point

The +X-axis of a Line is from its start-Point(1) to its end-Point(2)

The +Y-axis of a Line is at +90º from Line.

When you add a dimension that is a perpendicular-distance from the Line, the:

dimension is Positive if in +y-axis half of the Line (blue area in the image)

dimension is Negative if in the –y-axis of the Line (green area in the image)

In the top image:

Dimensions from the Line(1 to 2) to Points a and b are positive

Dimensions from the Line to Points c and d are negative


The X & Y-axes of a Part also have their own coordinate-system.

The bottom image to the left shows the Coordinate-System of the Y-axis

The local +x-axis of the Y-axis of a Part is along the Y-axis!

In the bottom image:

A dimension from the from Y-axis to Point (a or b) in the Blue area is Positive.

A dimension from the Y-axis to a Point (c or d) in the Green area is negative.