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 