In the unfortunate event that you find yourself in the clutches of a vampire, you'll know how much time you have left before you kick the bucket, thanks to physics students from the University of Leicester.
Turning to fluid dynamics, the students were able to calculate just how much time it would take for a vampire to drain 15 percent of the blood of an average human. The answer? Just 6.4 minutes.
Published in the Journal of Physics Special Topics, their research coincides with the 85th anniversary of "Dracula," which starred Bela Lugosi. According to the students, the rate they arrived considered blood was being drained from the external carotid artery located in the neck.
The students also stuck with 15 percent as the benchmark as any more loss of blood would cause a change in heart rate while less can be taken with the circulatory system being affected.
The main artery in the body, the aorta splits off into five other arteries. To calculate for blood flow velocity, the students chose to focus on the common carotid artery, assuming that all of the arteries are also of the same thickness.
First, they noted pressure difference by measuring the average human blood pressure in relation to the air pressure.
They then came up with average blood density at room temperature, deducing how much blood would flow out of a puncture wound in the neck, assuming vampire fangs would leave holes about 0.5mm wide each.
With the human body containing an average of 5 liters (1.3 gallons) of blood, having 15 percent of that taken would mean you'll lose 0.75 liters of your blood in 6.4 minutes. If you have the misfortune of meeting a vampire with little appetite control, you'll have about 42.7 minutes before you're completely drained.
On the upside, you won't actually see the moment your blood is completely drained.
Blood loss becomes fatal when you lose more than 40 percent of your blood volume. Given you're losing 15 percent of your blood every 6.4 minutes; you'll be dead at around 17.3 minutes.