If you've ever wondered how much time you'd have were a vampire to find your carotid artery and begin to guzzle, students at the University of Leicester have worked up an analysis.

Using fluid dynamics and a few interesting assumptions, they arrived at an average time of 6.4 minutes. Reporting in the Journal of Physics Special Topics, the school's peer-reviewed student journal, the students say that's how long it would take for an average vampire to drain an average human of 15 percent of his or her blood—any more and your heart rate changes, making blood drinking a "process of diminishing returns," as Gizmodo points out.

The students are assuming that vampires aren't out to kill but rather drink what they can and run (hence draining just 15 percent of the average human's 5 liters of blood); that each of the five arteries carrying blood away from the aorta are of equal size and smoothness (to establish blood flow velocity); that vampires aren't actually sucking out the blood (thus allowing the students to rely simply on the rate at which blood exits a puncture wound in one's neck); and that vampire fangs leave puncture holes roughly 0.5mm each.

So there you have it—on the 85th anniversary of Dracula, we now know that two tiny punctures in a neck will drain 15 percent of a person's blood in six minutes, 24 seconds.

You can now go and write a super-realistic script. (See why an archaeologist calls this a "vampire grave.")

This article originally appeared on Newser: A Vampire Can Drain Your Blood in a Matter of Minutes

More From Newser