Convert between px, rem and em for CSS sizing with a base font size you control. Rem and em units scale with the user font settings, which makes layouts more accessible and responsive than fixed pixels, but doing the math in your head while you style is tedious. Enter a pixel value and this tool shows the equivalent rem and em; enter a rem or em value and it shows the pixel equivalent. The root font size defaults to the browser standard of 16px but you can change it to match your own base, and every field recomputes live as you type. It is a fast helper for converting a design handoff into scalable CSS. Everything runs in your browser, so nothing you enter is ever sent to a server.