If Taylor Swift were a werewolf, how tall would she be in her wolf-form (assuming conservation of mass during shifting)?1
While there's normally no guarantee of mass conservation in fictional worlds (see my earlier estimation on The Incredible Hulk), we're explicitly told that the lovely Ms. Swift gains no mass in her hirsute form. As such, our first task is to figure how much she weighs at present. Since I only claim my estimates are accurate to within an order of magnitude, I could justifiably state her weight as being any number between 10 and 1000 pounds. Still, there's a reason Enrico Fermi was a physicist and not a carnival weight-guesser. I suspect it might have had something to do with disliking the feeling one gets after being whacked upside the head by the heel end of a starlet's shoe after you tell her she looks like she's roughly 1000 pounds. If only to avoid a nasty suit from Ms. Swift's lawyers, I'm going to try to be more accurate on this one.2
Google has apparently added a new feature that lists a celebrity's vital stats when you search for his/her name. I was surprised to find Ms. Swift listed at 5'11". While certainly slender, Taylor Swift is fairly tall. As such, a reasonable guess would be about 120 pounds.
If we consider gray wolves, we find they're about 34 inches tall at the shoulder and weigh roughly 85 pounds. In Ballparking, I discuss scaling in the context of animal sizes. Assuming everything remains proportional, an animal's mass m will increase as its height h cubed,
m ~ h3.
Taylor Swift weighs about 1.4 times as much as a typical wolf. If you scale a wolf up to this weight, its height will increase by a factor of about (1.4)1/3≈ 1.12. That's about 12 percent larger than a normal wolf. As such, a lupine Swift would be about 38 inches tall.
Great question, Jen! You can order Jen's new book on Amazon and follow her on Twitter at @jenlynnbarnes.
 What's with this correlation between lycanthropes and the name Taylor? Taylor Lautner, Taylor Swift, Chicago Wolves assistant coach Karl Taylor....
 I know weight is a sensitive topic for some people. Ms. Swift, if you're reading this and at all offended, I will personally do any calculation you like to make it up to you.
Aaron Santos is a physicist and author of the books How Many Licks? Or How to Estimate Damn Near Anything and Ballparking: Practical Math for Impractical Sports Questions. Follow him on Twitter at @aarontsantos.