# How much is (in kms) 1 degree of Longitude in the Earth?

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Leonardo Colavitti on 5 Sep 2017
Edited: José-Luis on 5 Sep 2017
Hi all, I am quiet new to Matlab and maybe my question sounds a bit trivial. I would like to know how many km corresponds 1 degree of LONGITUDE in the Earth (average radius: 6371 km, I am using the global model IASP91). I know that 1 degree in LATITUDE is about 111 km (k = (pi/180)*earth_radius) and that the corresponding longitude is a function of latitude. In particular, I suppose that near the equator the longitude in kms is about the cosine of the latitude at the same position. I would like to know if there is a more precise relationship or an existing function in Matlab which calculates that. Thank you so much for your help,
Leonardo

José-Luis on 5 Sep 2017
Edited: José-Luis on 5 Sep 2017

Leonardo Colavitti on 5 Sep 2017
Hi José, thanks for your answer and your timeless but I think that is not exactly what I am looking for. In fact, if I use the function deg2km and I type >> deg2km([1 1]) my answer is = 111.1949 111.1949 same values for Latitude and Longitude (is not really true). I already check the Mapping Toolbox but it is not very useful, also because in my case I don't have to compute any distance.
Cheers, Leonardo
José-Luis on 5 Sep 2017
If you're happy with assuming a WGS-ellipsoid:
I don't get it. Your question says:
"How much is (in kms) 1 degree of Longitude in the Earth?"
"I don't have to compute any distance."
What gives?
Just calculate the distance along a pair of coordinates.