I made a QGIS project to calculate some measures about the city I live in (in Belgium). Problem is, I noticed that I get very different results when measuring elements, in Google Maps vs in QGIS. Example: the same line measures 2.5km in Google Maps while it is 3.2km in QGIS.
I guess this is related to a wrong CRS - I didn't change anything when I created the project, those are the default values. Mine is EPSG:3857 for the project. It seems that there are also per-layer CRS, but they are also ESPG:3857 (WGS 84 / Pseudo-Mercator).
How could I fix my project so that I can measure the correct distances? Will it fix the existing layers and measures?