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GeezerVison is showing reference.wolfram.com — UnitSystem—Wolfram Documentation

UnitSystem

is an option for functions like AirTemperatureData that determines the units of the result.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Properties & Relations  
Possible Issues  
See Also
History
Cite this Page

UnitSystem

UnitSystem

is an option for functions like AirTemperatureData that determines the units of the result.

Details

  • The following settings for UnitSystem can be used:
  • "Imperial"return results in imperial units
    "Metric"return results in metric units
  • Specific units depend on the function and property used.
  • The default setting for UnitSystem is determined by your $GeoLocation and can be reset by adjusting $UnitSystem.

Examples

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Basic Examples  (1)

Control whether results are returned in metric or imperial units:

Wolfram Language code: AirPressureData[UnitSystem -> "Imperial"]
Wolfram Language code: AirPressureData[UnitSystem -> "Metric"]

Changing units can also be accomplished with UnitConvert:

Wolfram Language code: UnitConvert[%, "InchesOfMercury"]

Properties & Relations  (2)

Quantities returned for station properties can be adjusted with UnitSystem:

Wolfram Language code: WindDirectionData["KCMI", "Elevation", UnitSystem -> "Metric"]
Wolfram Language code: WindDirectionData["KCMI", "Elevation", UnitSystem -> "Imperial"]

The default value is determined by $UnitSystem, which is set by your computer's location:

Wolfram Language code: OptionValue[WindSpeedData, UnitSystem]
Wolfram Language code: $UnitSystem

Possible Issues  (2)

WindDirectionData does not return basic results in metric or imperial units:

Wolfram Language code: WindDirectionData[UnitSystem -> "Metric"]
Wolfram Language code: WindDirectionData[UnitSystem -> "Imperial"]

Improper settings for UnitSystem are ignored:

Wolfram Language code: WindSpeedData[UnitSystem -> "Foo"]

See Also

UnitConvert  AirPressureData  AirTemperatureData  WindDirectionData  WindSpeedData  WindVectorData

History

Introduced in 2014 (10.0)

Wolfram Research (2014), UnitSystem, Wolfram Language function, https://reference.wolfram.com/language/ref/UnitSystem.html.

Text

Wolfram Research (2014), UnitSystem, Wolfram Language function, https://reference.wolfram.com/language/ref/UnitSystem.html.

CMS

Wolfram Language. 2014. "UnitSystem." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/UnitSystem.html.

APA

Wolfram Language. (2014). UnitSystem. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/UnitSystem.html

BibTeX

@misc{reference.wolfram_2026_unitsystem, author="Wolfram Research", title="{UnitSystem}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/UnitSystem.html}", note=[Accessed: 12-November-2026]}

BibLaTeX

@online{reference.wolfram_2026_unitsystem, organization={Wolfram Research}, title={UnitSystem}, year={2014}, url={https://reference.wolfram.com/language/ref/UnitSystem.html}, note=[Accessed: 12-November-2026]}
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