How fast does pee come out? A gap in scientific knowledge

[Kupar 13,321]

From yesterday's Guardian newspaper kids quiz.

 

[wivace6455 29]

Looks like we need to do some research! If someone designs an experiment I'm sure a lot of us would be happy to participate!

[wettingman 568]

I would think it can vary significantly. It would depend on the size of a person's urethra and the actual pee hole, determining how fast it can cone out.

Also how badly the person needs to pee. If their bladder is full the pee would be pushed out harder. If they are too full and the bladder is seriously stretched, it may not be able to push as hard. You need to be in that sweet spot.

On one If my more memorable pees I must have hit that. I had to go pretty badly . When I let go I experienced a unusual sensation. I could feel my pee hole stretch as my pee gushed out at high velocity and pressure. Not at the time but I later recorded my urethra opening , it does not open very far .

It has been shown that females pee faster than males because of their short ,straight down urethra.

A study of the matter could be interesting but I don't know how you can calculate the actual speed of urine flow.

I do member some board college students measuring the speed of ketchup flowing from the bottle..   So maybe.... Who wants to volunteer to be a test subject.

 

 

 

 

[Pinguy94 104]

58 minutes ago, wettingman said:

I would think it can vary significantly. It would depend on the size of a person's urethra and the actual pee hole, determining how fast it can cone out.

Also how badly the person needs to pee. If their bladder is full the pee would be pushed out harder. If they are too full and the bladder is seriously stretched, it may not be able to push as hard. You need to be in that sweet spot.

On one If my more memorable pees I must have hit that. I had to go pretty badly . When I let go I experienced a unusual sensation. I could feel my pee hole stretch as my pee gushed out at high velocity and pressure. Not at the time but I later recorded my urethra opening , it does not open very far .

It has been shown that females pee faster than males because of their short ,straight down urethra.

A study of the matter could be interesting but I don't know how you can calculate the actual speed of urine flow.

I do member some board college students measuring the speed of ketchup flowing from the bottle..   So maybe.... Who wants to volunteer to be a test subject.

 

 

 

 

I have had similar where my urethra felt really stretched and a few of those times I had to go horribly bad, and I have recorded mine during a desperate pee and it can open fairly wide when needed 

[wivace6455 29]

Someone should check my math, but I think if you divide the flow rate in ml/second by the area of the urethra, that should be the speed of the flow right? If my math is right there then from some quick googling of averages I think a typical flow is more like 1.2 km per hour

[Kupar 13,321]

3 hours ago, wivace6455 said:

Someone should check my math, but I think if you divide the flow rate in ml/second by the area of the urethra, that should be the speed of the flow right? If my math is right there then from some quick googling of averages I think a typical flow is more like 1.2 km per hour

I don't know what averages you're using, but certainly volume flow rate divided by urethra cross sectional area would give you a velocity and that's probably the most straightforward way for averages. I don't fancy trying to measure my own urethra cross sectional area, and while you could try to measure the pee stream area with a close up photo I reckon the error in measurement would be big.

You could make a high speed video when the pee begins, with the subject standing or squatting close to a piece of paper with a scale marked on it. Or use a radar speed gun. Apparently there used to be one made by Mattel designed for use with Hotwheels toy cars https://www.eetimes.com/mattel-makes-a-real-radar-gun-on-the-cheap/

 

[MidoriLemonade85 2,353]

I have found that being desperate and squatting makes my pee squirt out faster, for sure. And hiss with the speed of it. My estimate would be 10kph. 

[glad1 2,831]

7 hours ago, Kupar said:

You could make a high speed video when the pee begins, with the subject standing or squatting close to a piece of paper with a scale marked on it. Or use a radar speed gun. Apparently there used to be one made by Mattel designed for use with Hotwheels toy cars https://www.eetimes.com/mattel-makes-a-real-radar-gun-on-the-cheap/

Great idea, Kupar! Perhaps we could all test our streams with a radar gun. Maybe even have a contest to see who's the fastest?

1 hour ago, MidoriLemonade85 said:

I have found that being desperate and squatting makes my pee squirt out faster, for sure. And hiss with the speed of it. My estimate would be 10kph. 

I can just picture signs posted in front of front of toilets and urinals, "sPEEd LIMIT 10" 🤣

[wivace6455 29]

7 hours ago, Kupar said:

You could make a high speed video when the pee begins, with the subject standing or squatting close to a piece of paper with a scale marked on it. Or use a radar speed gun. Apparently there used to be one made by Mattel designed for use with Hotwheels toy cars https://www.eetimes.com/mattel-makes-a-real-radar-gun-on-the-cheap/

 

Accuracy aside, radar gun definitely sounds like more fun!

[hold_on 132]

All I know is that getting older, it's been difficult for the pee to come out as fast as it did when I was younger. But I find if I really make an effort to relax my muscles my bladder will push it out faster.

[Pinguy94 104]

37 minutes ago, hold_on said:

All I know is that getting older, it's been difficult for the pee to come out as fast as it did when I was younger. But I find if I really make an effort to relax my muscles my bladder will push it out faster.

I have to agree with this forsure, I do a lot more dribbling or starting and stopping these days when I was younger it was full pressure most often 

[oliver2 4,409]

Unless I’m completely misremembering high school physics, you can get a very good measurement of speed by pissing in a particular angle then measuring how far it goes (before gravity pulls your stream to the ground)

[gldenwetgoose 21,466]

8 minutes ago, oliver2 said:

Unless I’m completely misremembering high school physics, you can get a very good measurement of speed by pissing in a particular angle then measuring how far it goes (before gravity pulls your stream to the ground)

That's a bloody good point...   trajectory I think is possibly the word you're thinking of.

Edit -  Of course if you're pissing in the wind you could get an entirely different result.  Or the people stood near you could too.

Edited October 2 by gldenwetgoose

[oliver2 4,409]

3 minutes ago, gldenwetgoose said:

Or the people stood near you could too.

Well, they might like it! It’s not likely, but it’s not impossible…

[Turkis viking 25]

Hmm easy, pee in a measuring cup or a container. Take the time on how long time it took to pee. Then measure on a kitchen weight. Use metric values where 1kg is the same as 1 liter for pee ( water). Then you get speed in ml/ sec

[Kupar 13,321]

11 hours ago, oliver2 said:

Unless I’m completely misremembering high school physics, you can get a very good measurement of speed by pissing in a particular angle then measuring how far it goes (before gravity pulls your stream to the ground)

R = range. V0 is initial velocity.

[wettingman 568]

5 hours ago, Turkis viking said:

Hmm easy, pee in a measuring cup or a container. Take the time on how long time it took to pee. Then measure on a kitchen weight. Use metric values where 1kg is the same as 1 liter for pee ( water). Then you get speed in ml/ sec

This makes sense. Wouldn't the distance from your pee hole to the container  matter . I am horrible at math

 

 

[DoctorDoctor 1,383]

There are so many good scientific ways posted here! Flow rate, radar, equations about trajectory and angles.

I remeber seeing a news article several years ago about a urinal installed in pubs/bars with sensors that measured both volume and speed (intensity?) of the piss stream. (I believe it was from Japan) I liked the electronic "leader board" that listed the recent top performers' statistics. Maybe they also need a toilet version for women.

 

There is always the old, subjective way of just filming a good piss and the distance the stream travels and having others comment on it! 😉

 

[Kupar 13,321]

15 hours ago, Turkis viking said:

Hmm easy, pee in a measuring cup or a container. Take the time on how long time it took to pee. Then measure on a kitchen weight. Use metric values where 1kg is the same as 1 liter for pee ( water). Then you get speed in ml/ sec

That will give you volume flow rate (ml/s) rather than speed (mph or m/s or km/h). Water comes out of a pressure washer at a faster speed than out of a hose pipe, but more water per second comes out of the hose.

Edited October 3 by Kupar

[JDAMS79 79]

On 9/30/2024 at 8:26 PM, wettingman said:

I would think it can vary significantly. It would depend on the size of a person's urethra and the actual pee hole, determining how fast it can cone out.

Also how badly the person needs to pee. If their bladder is full the pee would be pushed out harder. If they are too full and the bladder is seriously stretched, it may not be able to push as hard. You need to be in that sweet spot.

On one If my more memorable pees I must have hit that. I had to go pretty badly . When I let go I experienced a unusual sensation. I could feel my pee hole stretch as my pee gushed out at high velocity and pressure. Not at the time but I later recorded my urethra opening , it does not open very far .

It has been shown that females pee faster than males because of their short ,straight down urethra.

A study of the matter could be interesting but I don't know how you can calculate the actual speed of urine flow.

I do member some board college students measuring the speed of ketchup flowing from the bottle..   So maybe.... Who wants to volunteer to be a test subject.

 

 

 

 

This shows men have a faster flow rate til age 45 but the below chart from a study of women shows before age 50 the range in flow rate is huge with some pissing as much as 35 m/l per second.  I guess those are the ones in the videos we see filling huge bowls 🤪

Age group 

Average flow rate (mL/sec) 

14–45 years 

21 mL/sec for males, 18 mL/sec for females 

46–65 years 

12 mL/sec for males, 18 mL/sec for females 

66–80 years 

9 mL/sec for males, 18 mL/sec for females

 

[wettingman 568]

Yes the  dreaded enlarged prostate effect, which starts almost unnoticed in our mid forties. I am in that group at 72 and have had multiple procedures  to mitigate my enlarged prostate. It really sucks.

With females of course not only do they don't have a prostate . Their urethra is much shorter and just goes straight down . I have read this makes them able to pee faster. 

Edited October 3 by wettingman

[IdoPiddleSome2 10]

Water has a finite terminal velocity (in case we didn't already have enough variables to juggle here) 🙂. Then, sexual excitement (in response to Piƒsing) tends to change both internal ballistics & muzzle-velocity. My Peehole has lips with their own erectile schedule; they pout & squeexe my stream (to my delight & apparently theirs as well) this excites them to squeeze it more. So I think actual speed-detection tech would be the best way to get answers. In studies of small-arms ballistics, there are ways of measuring bullet-speed at the muzzle AND downrange. But this is tech for measuring speeds as high as Mach 3+. I don't know if Pee would even register. 

[wivace6455 29]

Anyone have one of those speed limit signs that tell you your speed nearby they could run and pee toward? It’s for science!

[Carb0nBased 644]

That's such a boy question to ask haha. Yes, many of the adult women and men on this site would still be interested, but we're a rather unusual sample of people. I also wonder what the purpose of that German study was. Possibly someone like Macsen grew up and wanted to set the record straight, but how did he manage to convince whoever he was working for to approve the study?

Also, I question the intelligence of anyone who would answer A or B for the star question! The lights of two adjacent windows in a city at night are much more than two arm lengths apart, and yet you can actually see them drift by as you ride in the car. The stars don't, so it doesn't take much thought to realize that they must be farther apart than the size of anything you see on the horizon.

[Fan of girls peeing 169]

Lol I don't know how fast the pee streams are but when girls piss fast then they pee really fast and very hard too! Girls when they pee fast then they definitely piss a lot faster than pretty much any guy lol.