Pasted screen shot is not scaled correctly

When I paste a window graphic pasted from the built-in Mac window capture tool (command-control-shift-4 then space) into an Outlook compose window, the graphic is huge. When I paste it into a Word window, it's fine. Both windows scaled to 100% (Outlook doesn't appear to have compose window scaling at all, but the print scaling is at 100%). Text in similar font size appears the same.