What metric unit of measurement would you use to measure a television screen?

In Australia TV screen size is specified in INCHES even though we have been using the metric system of length for more than 40 years. The size of a TV screen is stated as the LENGTH OF A DIAGONAL from the Top L.H. Corner of the glass, to the Bottom R.H. Corner of it's glass. If you want to convert that to CENTIMETRE, then multiply your Inch measurement, by 2.54.