The last Friday of the summer season is now upon us. As the days shorten and the leaves change and the year staggers toward its frigid terminus in the dead of winter, we at Wonkblog have been thinking about the inevitable conclusions of our own lives, and wondering how much of our potential we've squandered already.

So naturally, we made a fun little calculator to find out.

The name of the game here is average life expectancy. And we wanted to keep it as simple as possible, so it's based on the absolute minimum of variables: your age and your gender. Obviously, in reality, there are a lot of variables that go into your specific life expectancy, including, well, random chance.

The calculations come courtesy of Social Security, which publishes an actuarial life table showing the average years of life remaining for men and women at all ages from 0 to 119.

Here's the funny thing about life expectancy: your life expectancy at birth is different than what it is at later points in your life. For instance: a boy born now (age 0) can expect to live to 76. Does it follow, then, that a man who is 76 now can expect to die this year?

No. The average 76-year-old man has about 10 years more life remaining. How is that possible? The reason is that a newborn child has a lifetime of potential hazards ahead of it. There's that first year of heightened infant mortality risks, like SIDS. There's the risk of dying by accident or overdose in the teens and early 20s, when kids are prone to do stupid life-threatening things. And there's all those everyday health tragedies that take people in their 60s and 70s, like heart attacks and cancer.

But if you've made it to say, 76, then many of those risks are behind you. If you've survived that long, odds are good that you'll survive longer.

For this calculator, we've stuck to the absolute basic inputs of age and gender. But, as mentioned, plenty of other factors affect how long you'll live too. Do you eat well and exercise a lot? Add a few years. Are you a smoker? Take some away. If you want an insanely super-detailed calculator that's more akin to filling out a full medical questionnaire, check out this one at the University of Pennsylvania's website.

Again, these are just simple averages based on age and gender. But none of us is 100 percent average -- the "average person" is a statistical fiction. Not even the most complicated life expectancy calculator can fully account for all the variables, from health to genetics to plain old bad luck, that determine when a person will die.

But it's still a lot of fun, in a morbid way, for me (Chris) to know that the average man my age (35) has lived 45 percent of his life, and will die in the year 2058. Or that statistically speaking my wife will outlast me by 5 years. Or that my twins, who are 2, can expect to live to the year 2090, which practically makes them time travelers from the future!

But as they say on Game of Thrones: valar morghulis: all men must die.