You need to calibrate your monitor so that designs at 1:1 scale appear at real size. Do this when you first install the software or whenever you change your monitor.
Use Context > Measurement Units to change measurement units within software without changing operating system settings.
The first time you run the software, the measurement system will default to whatever the operating system is using. The measurement system can be changed via the droplist on the Context toolbar. It is recommended to use Metric setting for screen calibration to get the most precise measurements. See also Measurement units.
- Select Software Settings > Calibrate Screen.
- Measure the width and height of the dialog box. Make sure you measure edge to edge.
- Enter the precise measurements in the relevant fields.
- Click OK to confirm.