Pixel Assistant is an application that supports conversion between pixels, EMs, percent, and points. You need to choose your body font size in pixels (px) and out comes a complete pixel (px) to EM conversion table, making elastic web design with CSS a snap.
Pixels and points are static measurements, but commonly used in different mediums. Screens are measured in pixels - although points can be used on screens, they are the standard in printing because they are a factor of DPI.
Percent and EMs on the other hand are relative measurements. The size of an EM or percentage unit depends on its parent. If body text is sized at 12 pixels, then text set at 120% or 1.2 EM inside the body will be 1.2 * 12, or 14.4 pixels.
