When it comes to creeps, ghouls, and monsters, few are as popular, scary, and sexy as vampires. Between books, movies, and even television shows, few horror creatures have been around as long and with as many different versions.
Some vampires can turn into bats or monsters, some are afraid of crosses, and some vampires even sparkle.
One thing they all have in common, though, is their need to drink blood.
So how much blood would a vampire really have to drink to stay undead? Well, Duke Harten at Dose.com actually did the math to figure it out.
First, if you assume a vampire needs the same amount of calories a regular human needs, then an average blood-sucker would require almost 3,000 calories a day to maintain its weight.
Human blood contains 900 calories per liter. Considering the human body has about 5 liters of blood in it, a vampire would need to completely drain one human each day to survive.
Harten presented another method of calculating a vampire's daily blood intake derived from nature: The vampire bat.
Living in colonies of 100 bats, these bats can drink the blood of 25 cows per year.
Do some math and it turns out that a vampire-bat-person would need to drink 55 liters of blood per day. That's basically enough blood to drain all the members of Nickelback twice. It would come out to 4,015 people a year.
Either way you look at it, we sure are glad vampires aren't real.