Add an Excel file with a list of coordinates to QGIS as a layer?

You can often make a WKT (Well Known Text) column in Excel without too much fiddling, which effectively creates a spatial definition for points, lines or polygons within a single field.

What you want to do is create a WKT string, in the format:

POLYGON((X1 Y1, X2 Y2, X3 Y3, X4 Y4, X1 Y1))

You can create new columns in Excel with the below formulas. The first ('clean') substitutes the commas for spaces, then the semicolons for commas; the second ('wkt') creates a WKT string (concatenating text with &) - the only tricky part is finding and repeating the first coordinate pair to close the polygon:

• clean: =SUBSTITUTE(SUBSTITUTE(B2, ",", " "), ";", ",")

• wkt: ="POLYGON(("&C2&","&MID(C2,1, FIND(", ",C2)-1)&"))"

This can be saved as CSV, and the WKT field selected for import.

There are also some plugins for QGIS that provide data import through Excel files and they permitt some customization of input format. You can check MMQGIS or XYTools, these two I've worked with and perfom excellent. Some more might be available.