Clocks are everywhere, and almost everybody wears a watch. On each computer screen there is a clock ticking the seconds, minutes and hours away. Hundreds of times each day we want to know what time it is.

Why don’t we use the metric system to measure time? The metric system is used (in most civilized countries) for measuring all kinds of things, including length, area, volume, weight or mass, and even currency. We are used to measuring all these in a base 10 system. A kilometer is thousand meter, a centimeter is 1/100 of a meter, a liter equals 1000 milliliters, 1000 grams is a kilogram, etc.

But time is measured in a different way. Twenty four hours in a day, sixty minutes in an hour, sixty seconds in a minute, and yes, when we measure in fractions of a second we suddenly do it the metric way and we talk about milliseconds. Isn’t it time that we also use the metric system for measuring time? (people who think in ounces, inches, gallons and miles don’t have to read on)

Let’s explore how it would be to use Metric Time. Days would be the same, because the length of a day depends on the rotation of the earth. But we will have to change the length of hours, minutes, and seconds.

How we do it now The metric system 24 hours per day 10 hours per day 60 minutes per hour 100 minutes per hour 1,440 minutes per day 1,000 minutes per day 60 seconds per minute 100 seconds per minute 3,600 seconds per hour 10,000 seconds per hour 86,400 seconds per day 100,000 seconds per day

What does this mean for the length of hours, minutes and seconds? A second will get slightly shorter. Minutes will be a bit longer. And hours will take much longer. Metric hours are 2.4 times the hours as we know them now.

Convert "old" time to Metric time

1 metric second = 0.864 "old" second 1 metric minute = 1.44 "old" minute 1 metric hour = 2.4 "old" hour

What does it mean in practice?

There is no AM and PM anymore because we have only 10 hours in a day. Noon is at 5:00. If you are used to work from 9:00 AM to 5:00 PM, the metric clock means that you have to start at 3:75 (i.e. quarter to four) and by 7:08 you can call it a day.

Breaking world records

The world record ice skating on 5,000 meter is now 6 minutes and 3.32 seconds (Sven Kramer, November 2007). In the metric system this record would be 4 minutes and 20.51 seconds. This looks faster but it is exactly the same. But breaking the record should be easier because metric seconds (and thus hundredths of a second) are a bit shorter.

Cooper test

If you run a Cooper test with a metric watch, you will have to run 8 minutes and 33 second (8.33 minutes).

Abandon hours, minutes and seconds

A proper metric system for time would probably drop the use of hours, minutes, and seconds. The standard unit would be the day, and the metric hours would be called decidays, the minutes would be millidays, and a metric second would be 10 microdays.

Or keep the seconds

If we keep seconds as the basis for metric time, then a minute will be called decasecond, an hour will be 10 kiloseconds, and a day is 100 kiloseconds.

Expected problems

There are probably farmers who think that with metric time the cows would give less milk.

What time is it now in metric time?

Here is a clock (JavaScript) converting standard time to metric time:

Standard (24 hours) clock



Metric clock

See also this analog decimal clock.