My background as a technical illustrator makes me privy to all sorts of handy tools. This proportional scale is one that I have used for years to determine, with unfailing accuracy, the percentage required to resize an image or design. It is so simple to use and so handy that I am surprised that few outside of the technical/drafting world seem to have discovered it. Although I know and can use the mathematical formula to determine the resizing percentage, I much prefer the wheel. It requires no brain power, just a simple twist of the dials.
