Although the appearance of each font will differ, usually a standard size is 11 or 12 point (by way of comparison, this book is written in 12-point Trebuchet MS, and it’s written for easy reading, not essay-style formatting). If you go any bigger than 12, your essay starts looking like a billboard. The only reason I can surmise that anyone would be using a font size bigger than 12 is that they are attempting to make a short essay look longer than it is (perhaps trying to meet the requirement of, say, a five-page essay when you’ve only got three and a half pages). If this is the case, please trust me on this: you’re fooling no one. If you’ve reached the point in your life where you’re acting as a scholarship judge, that means you’ve probably written hundreds, if not thousands, of essays in your life – essays with those same page limits, requirements, etc.
We’ve been there before, monkeying with the font size (“Bump it up to 14 and see how that looks!”), the line spacing (“You think they’ll notice if I use 2.5 spacing instead of just double spacing?”), the leading, the kerning, putting a header and footer on each page, pushing the horizontal margins in, pushing the vertical margins down, etc. You name it, we’ve probably done it. Not only that, but when your essay comes up for review after dozens of others who didn’t fool around with formatting tricks, then yours will stand out like the proverbial aching digit.
On the other hand, if you go smaller than 10, things get difficult to read. Remember that, in most cases, these same committee members who know all the spacing tricks are quite a bit older than you, and for a lot of them, their eyesight isn’t what it used to be. Ever watch your grandpa struggle to read the TV Guide? (Do people still buy the TV Guide? I’m not sure. If they do, they’re sure to be grandparents.) And if they can’t read your essay, they can never find out how great and worthy of scholarship money you actually are. That’s why it’s important to keep the font at a reasonable size.