# Scaling of diagrams, contours and deformations
The scales at which diagrams, contour balloons and contour barrels are drawn and the magnification factor applied to displacements to arrive at a deformed image may be referred to as data scales.
Data scales can be explicitly specified in the Further options dialog box, which is accessed via the respective Settings dialogue boxes. If they have not been specified or if the Do auto-scale option has been checked then the scale is automatically calculated to result in a maximum size of diagram etc. of 15mm. If Lock scale is checked the scale for that diagram or contour is not affected by any automatic rescaling.
Scaling may be set to be to an engineering scale by checking Auto-scale to engineering scale in the Further options dialog box. When set, the calculated scale is rounded up to the next engineering scale.
The auto-scaling process includes a calculation of the extents of the data being displayed. The data extents are used when calculating contour values and when interpreting extents of interest in diagrams when expressed in terms of percentages.
Whether data scales or data extents are recalculated when the case is changed depends on the Recalculate displayed data scales on change of case and Recalculate extents of displayed data on change of case settings in the Graphics preferences.
Giving the Graphics > Display > Rescale data (Alt+Home) recalculates the scales for all current diagrams, contours and the deformed image. Rescale data is also available on the Graphic display toolbar.
A scale factor is applied to the calculated or specified data scale to result in a scale used for the display. The scale factor is provided to offer a convenient way of increasing or decreasing the displayed scale of diagrams, contours and deformed image. While the scale factors may be specified via the respective settings dialog box usually they are adjusted via the Double size of diagrams and Halve size of diagrams commands on the Graphic display toolbar. Rescale data resets the scale factor to unity.