Seconds, Minutes, and Hours: Abbreviations & Conversions

A millisecond is 1/1000 of a second. You’ll often see it in computer and technology documents in reference to processor speed, for example, as well as in some sporting competitions. While it’s hard to imagine from a human perspective, a single millisecond can make the difference between winning and losing a race at the Olympics.

The term was first used in 1909. It uses the common metric system prefix of “milli” to denote 1/1000.

There are two common abbreviations for millisecond:

• ms
• msec

If you are speaking about multiple milliseconds, you don’t change the abbreviation:

• 1 ms
• 2 ms
• 50 ms
• 1 msec
• 2 msec
• 50 msec

You can use the following conversions when working with milliseconds:

• There are 1,000 milliseconds in one second.
• There are 60,000 milliseconds in one minute.
• There are 3,600,000 milliseconds in one hour.

A second is 1/60 of a minute, and it represents one tick of the second hand around the face of a clock. According to Discover Magazine, people began to think in terms of seconds when clocks first began to use pendulums in the middle of the 17th century. In the 1950s and 1960s, scientists began measuring seconds using the far more accurate atomic clocks.

You can use the following abbreviations for seconds:

• sec
• s
• '' (informally)

If you are writing about more than one second, the plural abbreviation is the same as the singular. These examples can help:

• 1 sec
• 2 sec
• 45 sec
• 1 s
• 2 s
• 45 s
• 1''
• 2''
• 45''

The following conversions work for seconds:

• One second is 1,000 milliseconds.
• One minute is 60 seconds.
• There are 3,600 seconds in one hour.
• There are 86,400 seconds in one day.

A minute is 1/60 of an hour. According to Scientific American, this division is a relatively new concept. The first clocks showing minutes did not appear until the end of the 16th century, and even then, much of the general public was still unfamiliar with the concept of dividing an hour into 60 parts.

Rarely, an additional second or “leap second” is added to the length of a minute to keep things consistent and in line with the Earth's orbit around the sun.

To write an abbreviated version of minutes, you can use the following:

• min
• ' (informally)

It’s important to note that the abbreviation does not change when there are more minutes. The plural abbreviation is still “min,” as you can see in these examples:

• 1 min
• 5 min
• 45 min
• 1'
• 5'
• 45'

You can combine the informal prime abbreviations (similar to apostrophes) for minutes and seconds too, as in these examples:

• 1'45'' - one minute and 45 seconds
• 10'30'' - 10 minutes and 30 seconds
• 45'11'' - 45 minutes and 11 seconds

If you’re working with minutes, you can use the following conversions:

• One minute is 60,000 milliseconds.
• One minute is 60 seconds.
• There are 60 minutes in one hour.
• There are 1,500 minutes in one day.

An hour is 1/24 of a day. The concept of dividing a day into smaller parts began with the Ancient Egyptians, according to Scientific American. However, the idea of hours having a fixed length did not appear until the 14th century when mechanical clocks became common.

If you need to write a shorter version of “hours,” there are two common abbreviations you can use:

• h
• hr

Informally, more than one hour can be abbreviated as “hrs,” but in formal work, you still simply use “hr” for more than one hour. You can combine abbreviations for lengths of time too; the single letter versions are most common in this type of notation.

• 4 h 12 m 20 s
• 1 h 5 m 12 s
• 12 h 22 m
• 15 m 10 s

If you need to convert an hour into another unit, these conversions can help:

• One hour is 3,600,000 milliseconds.
• One hour is 3,600 seconds.
• One hour is 60 minutes.
• There are 24 hours in a day.

Common abbreviations like these are an important part of communication, especially when you’re writing. Understanding how to express yourself clearly and use the right abbreviations can help you make sure others understand what you’re saying.