# Geographic reference system in project **URL:** \ **Category:** Q&A\ **Tags:** gmt\ **Created:** [March 18, 2022, 4:17pm UTC](https://forum.generic-mapping-tools.org/t/geographic-reference-system-in-project/2717 "2022-03-18T16:17:28Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Brandon-Univ](https://avatars.discourse-cdn.com/v4/letter/b/43a26b/32.png) [@Brandon-Univ](https://forum.generic-mapping-tools.org/u/Brandon-Univ)\ **Post date:** [March 18, 2022, 4:17pm UTC](https://forum.generic-mapping-tools.org/t/geographic-reference-system-in-project/2717/1 "2022-03-18T16:17:28Z")
Hello, Here is my question: What is the geographic reference system used for the [project](https://docs.generic-mapping-tools.org/dev/project.html) function in GMT (and pyGMT)? WGS84 or another … ---
**Author:** ![maxrjones](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/maxrjones/32/2698_2.png) [@maxrjones](https://forum.generic-mapping-tools.org/u/maxrjones)\ **Post date:** [March 18, 2022, 4:24pm UTC](https://forum.generic-mapping-tools.org/t/geographic-reference-system-in-project/2717/2 "2022-03-18T16:24:59Z")
Calculations of specific great-circle and geodesic distances or for back-azimuths or azimuths are better done using [mapproject](https://docs.generic-mapping-tools.org/dev/mapproject.html) as [project](https://docs.generic-mapping-tools.org/dev/project.html#) is strictly spherical ([https://docs.generic-mapping-tools.org/dev/project.html#description](https://docs.generic-mapping-tools.org/dev/project.html#description)). ---
**Author:** ![Brandon-Univ](https://avatars.discourse-cdn.com/v4/letter/b/43a26b/32.png) [@Brandon-Univ](https://forum.generic-mapping-tools.org/u/Brandon-Univ)\ **Post date:** [March 18, 2022, 5:26pm UTC](https://forum.generic-mapping-tools.org/t/geographic-reference-system-in-project/2717/3 "2022-03-18T17:26:32Z")
Thank you for reply. In fact, I have to convert a script using [project](https://docs.generic-mapping-tools.org/dev/project.html) from GMT using [project](https://www.pygmt.org/v0.5.0/api/generated/pygmt.project.html) from pyGMT (to keep the same results). And by the way, I was wondering about the reference system used by default for these functions. ---
**Author:** ![pwessel](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/pwessel/32/30_2.png) [@pwessel](https://forum.generic-mapping-tools.org/u/pwessel)\ **Post date:** [March 18, 2022, 5:42pm UTC](https://forum.generic-mapping-tools.org/t/geographic-reference-system-in-project/2717/4 "2022-03-18T17:42:57Z")
Since it is spherical, it is the WGS-84 sphere with radius **6371008.771** ---
**Author:** ![Brandon-Univ](https://avatars.discourse-cdn.com/v4/letter/b/43a26b/32.png) [@Brandon-Univ](https://forum.generic-mapping-tools.org/u/Brandon-Univ)\ **Post date:** [March 19, 2022, 12:28pm UTC](https://forum.generic-mapping-tools.org/t/geographic-reference-system-in-project/2717/5 "2022-03-19T12:28:28Z")
Thank you!