# Microsecond

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One millionth of a second

microsecond Unit system SI Unit of time Symbol μs Conversions 1 μs in ... ... is equal to ... SI units 10−6 s

A **microsecond** is a unit of [time](/source/Time) in the [International System of Units](/source/International_System_of_Units) (SI) equal to one [millionth](/source/Millionth) (0.000001 or 10−6 or 1⁄1,000,000) of a [second](/source/Second). Its symbol is **μs**, sometimes simplified to **us** when [Unicode](/source/Unicode) is not available.

A microsecond is to one second, as one second is to approximately 11.57 days.

A microsecond is equal to 1000 [nanoseconds](/source/Nanosecond) or 1⁄1,000 of a [millisecond](/source/Millisecond). Because the next [SI prefix](/source/Metric_prefix) is 1000 times larger, measurements of 10−5 and 10−4 seconds are typically expressed as tens or hundreds of microseconds.

## Examples

- 1 microsecond (1 [μs](/source/Mu_(letter))) – cycle time for [frequency](/source/Frequency) 1×106 [hertz](/source/Hertz) (1 MHz), the inverse unit. This corresponds to radio wavelength [300](/source/1_E2_m) [m](/source/Metre) (AM [medium wave](/source/Medium_wave) band), as can be calculated by multiplying 1 μs by the [speed of light](/source/Speed_of_light) (approximately 3.00×108 m/s).

- 1 microsecond – the length of time of a high-speed, commercial [strobe light](/source/Strobe_light) flash (see [air-gap flash](/source/Air-gap_flash)).

- 1 microsecond – [protein folding](/source/Protein_folding) takes place on the order of microseconds (thus this is the speed of [carbon-based life](/source/Carbon-based_life)).

- 1.8 microseconds – the amount of time subtracted from the Earth's [day](/source/Day) as a result of the [2011 Japanese earthquake](/source/2011_T%C5%8Dhoku_earthquake_and_tsunami).[1]

- 2 microseconds – the lifetime of a [muonium](/source/Muonium) particle.

- 2.68 microseconds – the amount of time subtracted from the Earth's day as a result of the [2004 Indian Ocean earthquake](/source/2004_Indian_Ocean_earthquake_and_tsunami).[2]

- 3.33564095 microseconds – the time taken by [light](/source/Light) to travel one [kilometre](/source/Kilometre) in a [vacuum](/source/Vacuum).

- 5.4 microseconds – the time taken by light to travel one [mile](/source/Mile) in a vacuum (or radio waves point-to-point in a near vacuum).

- 8 microseconds – the time taken by light to travel one mile in typical [single-mode fiber optic cable](/source/Single-mode_optical_fiber).

- 10 microseconds (μs) – cycle time for frequency [100 kHz](/source/Hertz), radio wavelength [3](/source/Orders_of_magnitude_(length)) [km](/source/Kilometre).

- 18 microseconds – net amount per year that the length of the day lengthens, largely due to [tidal acceleration](/source/Tidal_acceleration).[3]

- 20.8 microseconds – [sampling](/source/Sampling_(signal_processing)) interval for digital audio with 48,000 samples/s.

- 22.7 microseconds – sampling interval for [CD](/source/Compact_disc) audio (44,100 samples/s).

- 38 microseconds – discrepancy in [GPS](/source/GPS) [satellite](/source/Satellite) time per day (compensated by clock speed) due to [relativity](/source/General_relativity) .[4]

- 50 microseconds – cycle time for highest [human-audible](/source/Hearing_(sense)) tone (20 kHz).

- 50 microseconds – to read the access latency for a modern solid state drive which holds non-volatile computer data.[5]

- 100 microseconds (0.1 ms) – cycle time for frequency 10 kHz.

- 125 microseconds – common sampling interval for telephone audio (8000 samples/s).[6]

- 164 microseconds – [half-life](/source/Half-life) of [polonium](/source/Polonium)-214.

- 240 microseconds – half-life of [copernicium](/source/Copernicium)-277.

- 260 to 480 microseconds - return trip ICMP ping time, including operating system kernel TCP/IP processing and answer time, between two Gigabit Ethernet devices connected to the same local area network switch fabric.

- 277.8 microseconds – a fourth (a 60th of a 60th of a second), used in astronomical calculations by [al-Biruni](/source/Al-Biruni) and [Roger Bacon](/source/Roger_Bacon) in 1000 and 1267 AD, respectively.[7][8]

- 490 microseconds – time for light at a 1550 nm frequency to travel 100 km in a singlemode fiber optic cable (where speed of light is approximately 200 million metres per second due to its [index of refraction](/source/Refractive_index)).

- The average human eye [blink](/source/Blink) takes 350,000 microseconds (just over 1⁄3 second).

- The average human finger [snap](/source/Finger_snapping) takes 150,000 microseconds (just over 1⁄7 second).

- A [camera flash](/source/Flash_(photography)) illuminates for 1,000 microseconds or 1 millisecond.

- Standard camera [shutter speed](/source/Shutter_speed) opens the shutter for 4,000 microseconds or 4 milliseconds.

- 584554 years of microseconds fit in 64 bits: (2**64)/(1e6*60*60*24*365.2425).

## See also

- [International System of Units](/source/International_System_of_Units)

- [Jiffy (time)](/source/Jiffy_(time))

- [Orders of magnitude (time)](/source/Orders_of_magnitude_(time))

- [Millisecond](/source/Millisecond)

- [Nanosecond](/source/Nanosecond)

- [Picosecond](/source/Picosecond)

## References

1. **[^](#cite_ref-1)** Gross, R.S. (14 March 2014). ["Japan quake may have shortened Earth days, moved axis"](https://www.jpl.nasa.gov/news/news.php?release=2011-080). JPL News. Jet Propulsion Laboratory. Retrieved 23 August 2019.

1. **[^](#cite_ref-IndianOceanNASA_2-0)** Cook-Anderson, Gretchen; Beasley, Dolores (January 10, 2005). ["NASA Details Earthquake Effects on the Earth"](https://www.nasa.gov/home/hqnews/2005/jan/HQ_05011_earthquake.html). NASA. Retrieved September 18, 2021.

1. **[^](#cite_ref-3)** MacDonald, Fiona. ["Earth's Days Are Getting 2 Milliseconds Longer Every 100 Years"](http://www.sciencealert.com/astronomers-find-a-day-on-earth-is-getting-longer-each-century). *ScienceAlert*. Retrieved 2017-03-08.

1. **[^](#cite_ref-4)** Richard Pogge. ["GPS and Relativity"](http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html). Retrieved 2011-10-01.

1. **[^](#cite_ref-5)** [Intel Solid State Drive Product Specification](http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/ssd-dc-s3500-spec.pdf)

1. **[^](#cite_ref-6)** Kumar, Anurag; Manjunath, D.; Kuri, Joy (2008), ["Application Models and Performance Issues"](https://linkinghub.elsevier.com/retrieve/pii/B9780123742544500041), *Wireless Networking*, Elsevier, pp. 53–79, [doi](/source/Doi_(identifier)):[10.1016/b978-012374254-4.50004-1](https://doi.org/10.1016%2Fb978-012374254-4.50004-1), [ISBN](/source/ISBN_(identifier)) [978-0-12-374254-4](https://en.wikipedia.org/wiki/Special:BookSources/978-0-12-374254-4), retrieved 2022-08-08{{[citation](https://en.wikipedia.org/wiki/Template:Citation)}}: CS1 maint: work parameter with ISBN ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_work_parameter_with_ISBN))

1. **[^](#cite_ref-7)** [al-Biruni](/source/Al-Biruni) (1879). [*The chronology of ancient nations: an English version of the Arabic text of the Athâr-ul-Bâkiya of Albîrûnî, or "Vestiges of the Past"*](https://books.google.com/books?id=pFIEAAAAIAAJ&q=thirds&pg=PA148). Translated by Sachau C Edward. [W. H. Allen](/source/W._H._Allen_%26_Co.). pp. 147–149. [OCLC](/source/OCLC_(identifier)) [9986841](https://search.worldcat.org/oclc/9986841).

1. **[^](#cite_ref-8)** [R Bacon](/source/Roger_Bacon) (2000) [1928]. *[The Opus Majus of Roger Bacon](/source/Opus_Majus)*. translator: BR Belle. [University of Pennsylvania Press](/source/University_of_Pennsylvania_Press). table facing page 231. [ISBN](/source/ISBN_(identifier)) [978-1-85506-856-8](https://en.wikipedia.org/wiki/Special:BookSources/978-1-85506-856-8).

## External links

- [The National Institute of Standards and Technology (NIST)](https://www.nist.gov/pml/time-and-frequency-division)

v t e Orders of magnitude of time by powers of ten Negative powers <1 attosecond attosecond femtosecond picosecond nanosecond microsecond millisecond Positive powers second kilosecond megasecond gigasecond terasecond and longer

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Adapted from the Wikipedia article [Microsecond](https://en.wikipedia.org/wiki/Microsecond) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Microsecond?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.