Time dilation is proportional to SQRT( 1 - V^2 / c^2) where V is the relative velocity and c is the velocity of light.

So for a jet airplane we get roughly SQRT( 1 - (600mph/3600 hrs/sec)^2 / 186000 miles/sec ^2) = SQRT( 1 - 8.03E-13) =
0.999999999999599. Or 400 parts per 1 quadrillion.

I’m an airline pilot. That’s probably the occupation with the highest average lifetime speed. Astonauts go a LOT faster, but not very often measured over their whole life.

I average 800 hours a year in the air and expect a 35 year career. If 100% of that time was at full cruise speed, then by retirement I’ll have aged some 3.12 picoseconds (3.12E-12 seconds) less than my brother who never travels. That’s roughly 1/300th of one nanosecond.

The Fountain of Youth it ain’t.

Because the formula is quadratic, not linear, slowing down from a 600 mph jet to a 60 mph car (10x speed reduction) produces a 100x reduction in time effect. So not quite 3 hours/day on the freeway will slow your life-clock by 1/30000th of a nanosecond compared to somebody who walks everywhere.

And at the limit case of driving your entire life, all 70 years, 24 x 7, at 60 mph will aggregate to 8.8 microseconds, or 8800 nanoseconds compared to somebody who never uses a vehicle their entire life.

See, spreadsheets can be fun, as long as the original premise is silly enough.

Wow, thanks LSLGuy! That’s superawesome. These little things amaze me. Also, that a speck of dust in China is exerting a gravitational pull on me, even though it’s really small.

Staying up all night working the redeye isn’t so healthy either. Neither is a steady diet of airline and/or airport food. Neither is being strapped into a chair 6 hours a day. It goes on and on …