Buffer is not yielding the appropriate size in QGIS

Question

I am trying to create a buffer of 10 kilometers around each dot already uploaded. The problem is that these buffers seem to be unreasobly larger than 10km. (Portugal). I have tried to use multiple multiple CRS but it doesn't work. Some people suggested to save layers as .shp but I can't see how to do that (maybe there was an update?). I have been using EPSG:4326 - WGS 84. I have tried some others and couldn't solve the issue.

I have read multiple suggestions in other Questions but couldn't solve so far.

Welcome to GIS SE. As a new user, please take the [Tour]. Please [Edit] the Question to provide details on exactly how you are attempting this task, and provide a screenshot or the resulting geometry (and report your measurement thereof). Do NOT use Web Mercator to make any distance calculations, for it is ALWAYS wrong in distance. — Vince, Jan 13 '23 at 18:27
Always try put some example of data, like a printscreen or a code to simplify your question — Marco Reliquias, Jan 13 '23 at 18:27
See this answer how to create correct buffer size, regardless of CRS: https://gis.stackexchange.com/a/438809/88814 — Babel, Jan 13 '23 at 22:12

score 4 · Accepted Answer · answered Jan 13 '23 at 18:24

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Any tool that uses distances must use a projected and non-geographic reference system. Reproject the geometry to the proper EPSG which should work correctly

answered Jan 13 '23 at 18:24

Marco Reliquias

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For example EPSG:27429 – BERA Jan 13 '23 at 18:25
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Yes BERA, As I didn't know which system, I preferred not to suggest so as not to confuse – Marco Reliquias Jan 13 '23 at 18:26
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And certainly not EPSG:3857 – Vince Jan 13 '23 at 18:27
I have now changed the project CRS to ESPG:27429. I changed the World Map and the layer as well. When I create the buffer the same thing happens... When you say "reproject" is there anything I should be particularly careful with? – Nuno Can Jan 13 '23 at 18:38
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Thanks @BERA, I have now been able to sort it! – Nuno Can Jan 13 '23 at 19:00

Buffer is not yielding the appropriate size in QGIS

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