CookieCal

CookieCal is a useful utility for cooks everywhere
CookieCal can show you the equivalent Celsius, Fahrenheit, or gas mark for all of the most common oven temperatures. CookieCal also provides you with a written description of the oven heat as some older recipes provide.
Additionally, you can enter a temperature in Fahrenheit, Celsius, or Kelvin, and CookieCal will automatically convert that temperature to the other two.
CookieCal easily converts between different types of volume measurements, weight measurements, or even between volume and weight measurements.
Need to convert an ingredient between volume and weight measurements that isn't listed? As long as you have the density for that ingredient, simply enter the density figure into the density box and CookieCal will do the rest.