**Abstract**

The current systems of units for time and angle, as well as the calendar, are archaic and have many weaknesses, in particular, they are not based on the decimal system, not rational and are unpractical. The article substantiates the need for their gradual replacement with metric time (MT), metric angle (MA) and metric calendar (MC). The basic versions of MT, MA and MC are described, which can be further developed. In them, base units, their multiples and submultiples are introduced as in the metric system, making the values of time and angles decimal numbers, which simplifies data recording and speeds up calculations. The base unit of MT, a decimal second (desecond), is 0.864 times shorter than the SI second and in a day, instead of 86400 seconds, there are 100000 deseconds. 100 deseconds form a milliday (deminute) and 100 millidays form a deciday (dehours). In MC, the day remains the base unit of the calendar time and contains 10 decidays, or 1000 millidays, or 100,000 deseconds. Multiples and submultiples of the time units are formed as decimal powers of a desecond and a day with metric prefixes. Multiple units of a day are decaday (10 days), centiday (100 days), kilo-, mega-, giga- and teradays. The days of our epoch are counted from January 1, 2001. Epochs of history are entered by 100 kilodays, or 274 years (near, middle and early history), by megadays (2.74 thousand years) and ten megadays (27.4 thousand years). Then May 18, 2022 is 7808th day of our epoch, 107808th day of near history and 1007808th day at shifting to megadays. In geology and astronomy, epochs contain gigadays (2.74 million years) and teradays (2.74 billion years). In MA with decimal angle is introduced as an exact analogue of MT, which simplifies data recording and calculations in engineering, geography and astronomy. A full angle (360 degrees) contains 10 zones, a zone has 100 deminute, and a milliday has 100 deseconds. On the sphere there are 10 zones of longitude (meridians) and 5 zones of latitude (parallels), where the latitude of the north pole is 0 and the south pole is 5. MC is based on MT, but decades are divided into two five day weeks, and 100 days (centidays) are divided into 4 months of 25 days. Centidays and months are only numbered and have no names. The year is a non-system unit for accounting for seasonal and traditional dates. Simplicity, rationality, greater precision and quickness at using MT, MA and MC are decisive in science, technology, economics, education and many other areas of society, and therefore a complete or partial transition to them is inevitable. During the transition period, they can be applied individually and in organizations in cases of obvious advantages and efficiency improvements.