# [Proj] Length of a deg in metres

Saulteau Don sault.don at gmail.com
Thu Nov 8 12:08:19 EST 2018

```I'm certain someone is going to be more knowledgeable than I, but I do
sometimes go back to this answer at GIS.se to get some insight.

https://gis.stackexchange.com/a/95397/1297

The user shares some formulas for obtaining both the scale and z-factor.

For other ellipsoids (the answer uses WGS84) it's a matter of determining
the length of one degree (longitude) at the equator in metres. For WGS84
it's 111320m for example.
The longitude is from the center of the area of interest.

Donovan

On Thu, Nov 8, 2018 at 8:22 AM Nicolas Cadieux <nicolas.cadieux at archeotec.ca>
wrote:

> Hi,
>
> I am writing to python code to calculate the length (in metres) of a
> degree of longitude at a certain degree of latitude.  I would like to
> take various ellipsoid in mind (WGS84, GRS80, Clarke 1866...).  The goal
> is to find the right scale (or z factor) when making slope or shade
> raster models when x and y are in long/lat and z in feet or meters.  Can
> someone point me in the right direction to do this in using Proj?  Is
> Proj the best option for this?
>
> Thanks,
>
> Nicolas
>
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