WOLFRAM

Wolfram Language & System Documentation Center

CompatibleUnitQ[quantity1,quantity2]

returns True if quantity1 and quantity2 have compatible units, and False otherwise.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Properties & Relations  
Possible Issues  
See Also
Tech Notes
Related Guides
History
Cite this Page

CompatibleUnitQ

CompatibleUnitQ[quantity1,quantity2]

returns True if quantity1 and quantity2 have compatible units, and False otherwise.

Details

Examples

open all close all

Basic Examples  (3)

Test whether two Quantity objects are compatible:

Wolfram Language code: CompatibleUnitQ[Quantity[3, "Feet"], Quantity[8, "Meters"]]

Test whether two units are compatible:

Wolfram Language code: CompatibleUnitQ["Feet", "Pounds"]

Test compatibility of a sequence of quantities and units:

Wolfram Language code: CompatibleUnitQ[Quantity[3, "Meters"], Quantity[6, "Yards"], "Kilometers"]

Scope  (6)

Test compatibility of Quantity objects:

Wolfram Language code: CompatibleUnitQ[Quantity[2.5, "Seconds"], Quantity[4 / 3, "Minutes"]]
Wolfram Language code: CompatibleUnitQ[Quantity[2, "Seconds"], Quantity[1.3, "Meters" / "Seconds"]]

Test compatibility of unit expressions:

Wolfram Language code: CompatibleUnitQ["Becquerels", "Seconds" ^ -1, "Hertz"]

Test compatibility of the elements of lists:

Wolfram Language code: CompatibleUnitQ[{Quantity[100, "Meters"], {Quantity[1, "Miles"], Quantity[3, "Kilometers"]}}]
Wolfram Language code: CompatibleUnitQ[{"Meters", "Centimeters", "Years"}]

Test whether QuantityArray objects have compatible units:

Wolfram Language code: CompatibleUnitQ[QuantityArray[{2.3, 1.5, 9.0}, "Arcminutes"]]
Wolfram Language code: CompatibleUnitQ[QuantityArray[{{1, 2}, {3, 4}, {5, 6}}, {"Meters", "Seconds"}]]

Use MixedUnit specifications:

Wolfram Language code: qa = Quantity[MixedMagnitude[{1, 80}], MixedUnit[{"Meters", "Centimeters"}]] qb = Quantity[MixedMagnitude[{5, 10}], MixedUnit[{"Feet", "Inches"}]]
Wolfram Language code: CompatibleUnitQ[qa, qb, "Yards"]

Use DatedUnit specifications:

Wolfram Language code: CompatibleUnitQ[DatedUnit["Kelvins", 1967], "DegreesCelsius"]
Wolfram Language code: CompatibleUnitQ[DatedUnit["Meters", 1889], DatedUnit["Kilograms", 1889]]

Properties & Relations  (6)

CompatibleUnitQ returns True when its elements have the same UnitDimensions:

Wolfram Language code: CompatibleUnitQ[Quantity[10, "Meters"], Quantity[7, "Inches"]]
Wolfram Language code: UnitDimensions /@ {Quantity[10, "Meters"], Quantity[7, "Inches"]}

An IndependentUnit object is only compatible with itself:

Wolfram Language code: CompatibleUnitQ[IndependentUnit["myUnits"], IndependentUnit["myUnits"]]
Wolfram Language code: CompatibleUnitQ[Quantity[3, IndependentUnit["myUnits"]], Quantity[-2, "Nano"IndependentUnit["myUnits"]]]

Known units are not compatible with IndependentUnit objects of the same name:

Wolfram Language code: CompatibleUnitQ["Meters", IndependentUnit["Meters"]]

Numeric expressions are treated as dimensionless quantities:

Wolfram Language code: CompatibleUnitQ[Quantity[50, "Percent"], π]

CompatibleUnitQ will automatically attempt to interpret an unknown unit string:

Wolfram Language code: KnownUnitQ["Henryes"]
Wolfram Language code: CompatibleUnitQ["Seconds" / "Siemens", "Henryes"]
Wolfram Language code: KnownUnitQ["Henries"]

CompatibleUnitQ with one argument is similar to KnownUnitQ:

Wolfram Language code: {CompatibleUnitQ["Meters"], KnownUnitQ["Meters"]}

CompatibleUnitQ accepts numeric expressions:

Wolfram Language code: {CompatibleUnitQ[3], KnownUnitQ[3]}

CompatibleUnitQ attempts to interpret unknown unit strings:

Wolfram Language code: {CompatibleUnitQ["second"], KnownUnitQ["second"]}

If elements other than quantities and units are present, CompatibleUnitQ returns False:

Wolfram Language code: CompatibleUnitQ[Quantity[1, "Feet"], x]
Wolfram Language code: CompatibleUnitQ[x]

Possible Issues  (1)

Temperatures and temperature differences are compatible, but may not always be freely converted to one another:

Wolfram Language code: CompatibleUnitQ["DegreesCelsiusDifference", "DegreesFahrenheit"]
Wolfram Language code: UnitConvert[Quantity[3., "DegreesCelsiusDifference"], "DegreesFahrenheit"]
Wolfram Research (2012), CompatibleUnitQ, Wolfram Language function, https://reference.wolfram.com/language/ref/CompatibleUnitQ.html (updated 2022).

Text

Wolfram Research (2012), CompatibleUnitQ, Wolfram Language function, https://reference.wolfram.com/language/ref/CompatibleUnitQ.html (updated 2022).

CMS

Wolfram Language. 2012. "CompatibleUnitQ." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2022. https://reference.wolfram.com/language/ref/CompatibleUnitQ.html.

APA

Wolfram Language. (2012). CompatibleUnitQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/CompatibleUnitQ.html

BibTeX

@misc{reference.wolfram_2026_compatibleunitq, author="Wolfram Research", title="{CompatibleUnitQ}", year="2022", howpublished="\url{https://reference.wolfram.com/language/ref/CompatibleUnitQ.html}", note=[Accessed: 12-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_compatibleunitq, organization={Wolfram Research}, title={CompatibleUnitQ}, year={2022}, url={https://reference.wolfram.com/language/ref/CompatibleUnitQ.html}, note=[Accessed: 12-June-2026]}