Graphic designers may find more use for this plugin than web designers, but it can.
12+ Sketch To Scale
Pics. In the propertymanager, under entities to scale, select sketch entities for sketch item or annotations. In edit sketch mode click scale entities (sketch toolbar) or tools > sketch tools > scale.
Every designer's idea starts on paper, then transforms through software. One way is to go ahead and pad the sketch you made from the scan. If you really want the sketch to scale, you can break the constraints by using transform in the sketch.
Use guides to scale to specific dimensions.
Change the size of the selected object using the pull tool. When you scale an object this way, you may use either desired pixel dimensions or a percentage to multiply by. Use the scale solid or surface: Every designer's idea starts on paper, then transforms through software.