# Time measurements

## Introduction

It is common in our daily lives to hear questions such as:

• How long is this soccer match?
• How long is this trip?
• How long is this course?
• What is the best time for this runner?

All these questions will be answered based on a standard unit of time measurement.

The unit of time chosen as the default in the International System (IS) is the second.

## Second

The Sun was man's first clock: the natural time interval between successive passages of the Sun over a given meridian gives rise to the solar day.

The second (s) is the time equivalent to of the average solar day.

Time measurements do not belong to the Decimal Metric System.

## Multiples and submultiples of the second

Unit table

 Multiples minutes hour day min H d 60s 60 min = 3,600 s 24 h = 1,440 min = 86,400s

They are submultiples of the second:

• tenth of a second
• hundredth of a second
• millisecond

Watch out: never write 2.40h as a representation of 2h40min, as the time measurement system is not decimal. Watch: Tip: Use our online converter to convert between different measurements.

Next: Other Units of Measure