SI - Measuring Time

Measuring intervals of time is somewhat unusual compared to working with distance and length. Fractions of seconds are typically measured using the standard prefixes associated with the (decimal) metric system.

Fractions of Seconds:
Prefix Abbrev. Decimal Form Exponent
seconds s. 1. 100
milliseconds ms. .001 10-3
microseconds µs. .0000001 10-6
nanoseconds ns. .000000001 10-9
picoseconds ps. .000000000001 10-12

Whereas fractions of seconds adhere to the standards laid out within the metric system, multiples of seconds are often measured in terms of minutes and hours.

Multiples of Seconds:
Prefix Abbrev. # Seconds Exponent
seconds s. 1 sec. 600
minutes min. 60 secs. 601
hours hrs. 3600 secs. 602

The system of hours:minutes:seconds is a carryover from a much older system and represents a departure from the decimal notation used within the metric system.