Peeing might seem straightforward, but there’s actually more to consider for good bladder health. Many of us appreciate the peaceful moment of sitting in the bathroom—anyone else?
But it turns out that we should be more mindful during these breaks, thanks to something called the “21-second rule” suggested by scientists.
Mechanical engineering students at Georgia Tech studied urination duration across different animals and developed the “Law of Urination.”
By observing high-speed videos, they found that animals weighing over three kilograms (6.6 pounds) typically take about 21 seconds to empty their bladders, while smaller animals, like rats, finish in a fraction of a second. Urination time, they found, is not just about bladder pressure; gravity plays a role as well, according to IFL Science.
Their 2014 study explains: “How can bladders of 0.5 kg and 100 kg both empty in nearly the same time? Larger animals have longer urethras, which create a greater gravitational force that increases flow. This added urethra length allows larger animals to empty their bladders in about the same time.”
The study suggests that the ideal peeing time for humans is around 21 seconds. So, next time you go, consider timing yourself. If you usually take more or less than this, it could mean you’re using the bathroom too often or too rarely.
Frequent urination can signal an “overactive bladder,” while holding it too long may raise the risk of UTIs, kidney disease, and even bladder enlargement or rupture.
For optimal health, be sure to stay hydrated and take regular bathroom breaks.