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=usft
Often when working with GNSS data the timestamps are presented in GPSweeks, 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 
link  International Link 
usin  U.S. Surveyor’s Inch 
usft  U.S. Surveyor’s Foot 
usyd  U.S. Surveyor’s Yard 
usch  U.S. Surveyor’s Chain 
usmi  U.S. Surveyor’s Statute Mile 
indyd  Indian Yard 
indft  Indian Foot 
indch  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 
grad  Grad 
rad  Radian 
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 