What is millisecond?

A millisecond is a unit of time equal to one thousandth of a second. It is used in computing, networking, audio and video processing, and measuring reaction times and signal latencies.

Real-world uses

Milliseconds are critical in computing for measuring network latency (ping times), database query performance, and real-time system response. Financial trading platforms measure order execution in milliseconds, and human reaction time averages about 250 ms.

History

The millisecond became a practical unit with the invention of precise mechanical chronographs in the 19th century. Its importance exploded with electronic computing, where operations occur in millisecond and sub-millisecond timescales.

Common mistakes

Confusing milliseconds with microseconds in performance profiling—they differ by a factor of 1,000. Also, assuming human perception cannot detect millisecond differences, when in fact audio delays above 10 ms are perceptible.

What is second?

The second is the SI base unit of time. It is used globally in science, engineering, computing, and everyday life, and is the foundation upon which all other time units are built.

Real-world uses

The second is the SI base unit of time, fundamental to all scientific measurement, computing clock cycles, athletic timing, and GPS satellite synchronization. Everyday timekeeping, cooking timers, and traffic light cycles all rely on seconds.

History

The concept of dividing the day into 86,400 parts dates to ancient Babylonian and Egyptian timekeeping. Since 1967, the SI second has been defined as 9,192,631,770 periods of the radiation from a caesium-133 atom.

Common mistakes

Assuming a second has always been 1/86,400 of a day. The modern SI second is defined by caesium atom vibrations and is independent of Earth's rotation, which varies slightly due to tidal friction.

When is this conversion used?

Converting millisecond to second is useful in the time domain when comparing values across different measurement standards or applying formulas that require a specific unit.

Worked examples

1 millisecond = 0.001 second

1 second = 1 second

How to convert millisecond to second

To convert millisecond to second, multiply the value by 0.001.

To convert second back to millisecond, multiply by 1,000.

Measurement standards

The SI second is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom, maintained by the BIPM and national metrology institutes worldwide.

Did you know?

Earth's rotation is gradually slowing due to tidal friction with the Moon. To keep atomic time aligned with solar time, "leap seconds" have been inserted 27 times since 1972 — though they are scheduled to be abolished by 2035.

Quick reference: millisecond to second

millisecondsecond
0.10.0001
0.50.0005
10.001
20.002
50.005
100.01
250.025
500.05
1000.1
2500.25
5000.5
1,0001

Common values

millisecondsecond
Blink of an eye300 millisecond0.3 second
Average pop song210,000 millisecond210 second
Feature film7,200,000 millisecond7,200 second
One work day (8 hrs)28,800,000 millisecond28,800 second
One calendar year3.153600e+10 millisecond31,536,000 second