I am trying to find the equivalent LegendMarkerSize value to the size specified for special characters when using LegendMarkers. So far I found LegendMarkerSize 14 generates symbols close to 22 set for those characters. Please compare code below, one using Graphics for LegendMarkers, the other using special charaters:
SwatchLegend[{Red, Blue, Orange},{"2007", "2011", "2012"}, LegendMarkers-> {Graphics[Disk[{0, 0}]],Graphics[Polygon[{{1, 0}, {0, 1}, {-1, 0}, {0, -1}}]],Graphics[Rectangle[]]}, LegendMarkerSize -> 14]
and
PointLegend[{Red, Blue, Orange}, {"2007", "2011", "2012"},LegendMarkers -> {{"\[FilledCircle]", 22}, {"\[FilledDiamond]", 22}, {"\[FilledSquare]", 22}}]
Also as a side note, the symbol generated by LegendMarkers using Graphics seem to have a surrounding edge while the one using special character looks cleaner.
LegendMarkers -> {{"\[FilledCircle]", 20}, {"\[FilledDiamond]", 22}, {"\[FilledSquare]", 27}}
for the second example seems to produce roughly the same result as the first example. They are spaced farther apart, though. $\endgroup$