📐 Unit Converter
Convert between common units — temperature, weight, length, and area.
Temperature
Weight
Length
Area
Australia goes metric — a surprisingly recent change
It's easy to forget that Australia only switched to the metric system in the 1970s. Before then, Australians used the imperial system — pounds, ounces, miles, yards, gallons, and Fahrenheit — inherited from Britain.
The Metric Conversion Act 1970 established the Metric Conversion Board, which managed the transition over several years. "Metric Day" — 1 July 1974 — marked the official switchover for most everyday measurements. Speed limit signs changed from miles per hour to kilometres per hour overnight.
- Temperature: Australia switched from Fahrenheit to Celsius in 1972. Older Australians sometimes still refer to temperatures in Fahrenheit ("it was 100 degrees in the shade!").
- Holdouts: Some measurements stubbornly refused to metrify. Screen sizes are still in inches. Tyre pressure is still PSI. Shoe sizes never went metric. Aviation uses feet and nautical miles globally.
- Body weight: Australians officially use kilograms, but many older Australians still think in stones and pounds when discussing personal weight.
- The US anomaly: The US has been "officially" committed to metric since the Metric Conversion Act of 1975 but has made almost no practical progress. NASA famously lost the Mars Climate Orbiter in 1999 because one team used metric units and another used imperial.
🦘 Fun fact: The $327 million Mars Climate Orbiter was lost in 1999 because Lockheed Martin sent thruster data in pound-force seconds while NASA's navigation team expected newton-seconds. The spacecraft burned up in the Martian atmosphere. The metric/imperial confusion cost the equivalent of over half a billion dollars in today's money.