Incidentally, there was a metric calendar, invented alongside the metric system: http://en.wikipedia.org/wiki/French_Republican_Calendar http://en.wikipedia.org

Incidentally, there was a metric calendar, invented alongside the metric system: http://en.wikipedia.org/wiki/French_Republican_Calendar http://en.wikipedia.org/wiki/French_Republican_Calendar It never gained much hold, probably for two reasons - its units were too far off the customary units, hard to convert, and didn't fit into the neat 10^3 system. The other units (metres, kilograms) were close or easily convertible into what they replaced (ell and pound, both at approximately 0.5 metres/kilograms). - the number of days in a year is set, so you never end up at a neatly decimal system with e.g. 10^3 days in a year (and even worse, it's a weird fraction leading to leap years and seconds)