Ultimate Unit Converter

Free online conversion calculator

Convert common, technical, and obscure units in one place.

Ultimate Unit Converter lets you build custom conversion sections for length, area, volume, mass, temperature, speed, torque, pressure/stress, density, data, typography, and more. Add rows, compare multiple values, and toggle obscure units when you need unusual measurements like football fields, nautical miles, barrels of oil, light-years, or Planck length.