Launch QuickScale and open a drawing.
If the drawing has not previously been calibrated, you must calibrate it first. See "Calibrating a drawing with a known scale" or See "Calibrating a drawing with an unknown scale" as appropriate.
On the 'Home' toolbar, click the 'Line' button from the 'Measuring' section.
Navigate to the part of the drawing to be measured and click the mouse at the beginning of the line you wish to draw. Now move the mouse to the end of the line and click again.

The Line tool is suitable for simple length, width, height measurements.
On the 'Home' toolbar, click the 'Path' button from the 'Measuring' section.
Navigate to the part of the drawing to be measured and click the mouse at the beginning of the path you wish to draw. Now move the mouse to the next point on the path and click again. Continue along the path clicking on all the necessary points along that path.
To finish measuring the path, either press the "Esc" (escape) button on your keyboard, or, right-mouse click on the last point on the path and, from the pop-up menu, select "Complete".

The Line tool is suitable for taking-off perimeters, skirtings, pipe runs, etc.
On the 'Home' toolbar, click the 'Area' button from the 'Measuring' section.
Navigate to the part of the drawing to be measured and click the mouse at the beginning of the area you wish to measure. Now move the mouse to the next point of the area and click again. Continue around the area clicking on all the necessary points along the perimeter until you return to the start point.

To finish measuring the area, either press the "Esc" (escape) button on your keyboard, or, right-mouse click on the last point on the area and, from the pop-up menu, select "Complete".
To measure the area of a circular shape, such as an arch, select the Area tool button and click on a point on the circumference. Move the mouse around the circumference and click at regular intervals. The closer the click points to each other, the more accurate the measurement will be.

Any area can be represented as either a squared unit of measure or a linear unit. In other words, you can toggle between area or perimeter measurements via the Dimensions pane. Just select the item's 'Units' entry in the Dimensions pane and, if it's an area, you'll be able to change from, for example, square metres to metres:

We all make mistakes! QuickScale provides a range of options for deleting measurements - as well as for recovering any accidental deletions!
To delete a measurement, click the 'Select' button from the 'Measuring' area of the 'Home' tab and select the measurement to be deleted. You can now either:
If, whilst drawing a measurement line, you make a mistake you can either click the 'Undo' button from the 'Edit' area of the 'Home' tab or press and hold the 'Ctrl' (Control) key on your keyboard and then press the 'Z' key.
To restore an item you just deleted, click the 'Redo' button from the 'Edit' area of the 'Home' tab. Alternatively, press and hold the 'Ctrl' (Control) key on your keyboard and then press the 'R' key.
To clear all measurements from a drawing (including calibrations), click the 'Clear All' button from the 'Edit' area or the 'Home' tab. You'll get a warning message because you cannot restore a 'Clear All' action. Therefore, if you wish to proceed, click the 'Yes' button.