# Unit conversion¶

New in version 5.0.0.

Convert between various distance, angular and time units.

 Alias unitconvert Domain 2D, 3D or 4D Input type Any Output type Any

There are many examples of coordinate reference systems that are expressed in other units than the meter. There are also many cases where temporal data has to be translated to different units. The unitconvert operation takes care of that.

Many North American systems are defined with coordinates in feet. For example in Vermont:

+proj=pipeline
+step +proj=tmerc +lat_0=42.5 +lon_0=-72.5 +k_0=0.999964286 +x_0=500000.00001016 +y_0=0
+step +proj=unitconvert +xy_in=m +xy_out=us-ft


Often when working with GNSS data the timestamps are presented in GPS-weeks, but when the data transformed with the helmert operation timestamps are expected to be in units of decimalyears. This can be fixed with unitconvert:

+proj=pipeline
+step +proj=unitconvert +t_in=gps_week +t_out=decimalyear
+step +proj=helmert +epoch=2000.0 +t_obs=2017.5 ...


## Parameters¶

+xy_in=<unit> or <conversion_factor>

Horizontal input units. See Distance units and Angular units for a list of available units. <conversion_factor> is the conversion factor from the input unit to metre for linear units, or to radian for angular units.

+xy_out=<unit> or <conversion_factor>

Horizontal output units. See Distance units and Angular units for a list of available units. <conversion_factor> is the conversion factor from the output unit to metre for linear units, or to radian for angular units.

+z_in=<unit> or <conversion_factor>

Vertical output units. See Distance units and Angular units for a list of available units. <conversion_factor> is the conversion factor from the input unit to metre for linear units, or to radian for angular units.

+z_out=<unit> or <conversion_factor>

Vertical output units. See Distance units and Angular units for a list of available units. <conversion_factor> is the conversion factor from the output unit to metre for linear units, or to radian for angular units.

+t_in=<unit>

Temporal input units. See Time units for a list of available units.

+t_out=<unit>

Temporal output units. See Time units for a list of available units.

## Distance units¶

In the table below all distance units supported by PROJ are listed. The same list can also be produced on the command line with proj or cs2cs, by adding the -lu flag when calling the utility.

Label

Name

km

Kilometer

m

Meter

dm

Decimeter

cm

Centimeter

mm

Millimeter

kmi

International Nautical Mile

in

International Inch

ft

International Foot

yd

International Yard

mi

International Statute Mile

fath

International Fathom

ch

International Chain

us-in

U.S. Surveyor’s Inch

us-ft

U.S. Surveyor’s Foot

us-yd

U.S. Surveyor’s Yard

us-ch

U.S. Surveyor’s Chain

us-mi

U.S. Surveyor’s Statute Mile

ind-yd

Indian Yard

ind-ft

Indian Foot

ind-ch

Indian Chain

## Angular units¶

New in version 5.2.0.

In the table below all angular units supported by PROJ unitconvert are listed.

Label

Name

deg

Degree

## Time units¶

In the table below all time units supported by PROJ are listed.

Label

Name

mjd

Modified Julian date

decimalyear

Decimal year

gps_week

GPS Week

yyyymmdd

Date in yyyymmdd format