InchMetric is an easy to use Inch to Millimeter converter and vice versa.
The input method is extremely fast and requires only a minimum of keystrokes. To convert 12 3/8 Inches to millimeters, just type [1] [2] [Inch] [3] [1/8].
The result is computed immediately after every keystroke.
The result accuracy can be set to your needs from 1/2 inches to 1/128 inches and from 1mm to 0.001mm.