A simple calculator to convert between various units.

Includes length, area and volume and the use of prefixes in units. With worked examples and animations.

Gives equal values for areas, volumes, circle measurements, computer storage, currencies, distance and length, energy, fuel consumption, power, pressure, speed, temperature, time, torque, and weights.

Online metric conversion calculator includes metric, US customary and Imperial unit conversions.

Dictionary of metric units explaining the principles and history of the system.

History and description of clocks with lessons on telling the time. Includes an interactive tutor. [Requires Java]