# How fast is blood? **URL:** \ **Category:** Factual Questions\ **Created:** [May 6, 2000, 6:20pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767 "2000-05-06T18:20:40Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Breckinshire](https://avatars.discourse-cdn.com/v4/letter/b/71c47a/32.png) [@Breckinshire](https://boards.straightdope.com/u/Breckinshire)\ **Post date:** [May 6, 2000, 6:20pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/1 "2000-05-06T18:20:40Z")
When the heart expands (heretofore known as expansion :)), it sends blood (heretofore known as “metallic tasting red stuff”) through the body (heretofore known as **\** ). What is the speed of this blood? I’m sure it varies from person to person, but what is the average speed? AskJeeves was of absolutely no use on this one (SEE: [Make Blood Fast and Legitimate!](http://paul.merton.ox.ac.uk/computing/vampire.html)). ---
**Author:** ![BobT](https://avatars.discourse-cdn.com/v4/letter/b/8e8cbc/32.png) [@BobT](https://boards.straightdope.com/u/BobT)\ **Post date:** [May 6, 2000, 6:33pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/2 "2000-05-06T18:33:13Z")
Mosby’s Nursing dictionary says that blood travels about 30 cm/second and takes 20 seconds to travel through the whole body. ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [May 6, 2000, 6:43pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/3 "2000-05-06T18:43:45Z")
It depends on the cross-sectional area of the vessel and the blood flow. According to a _Physiological Basis of Medical Practice_ > [@](#): > > v = V / (pi\*r^2) > > v is average velocity of blood in mm/s; V flow of blood in mm^3/s; r is radius of vessel in mm. > > If the flow is 3000 cubic millimeters per second and the diameter of the vessel is 4 mm., the velocity of blood is 238 mm/s. > > The velociy in the larger arteries of the dog during rest is from 0.1 to 0.2 meter per second, in the capillaries about 0.5 mm per second, and in the medium sized and large veins from 0.06 to 0.2 meters per second. ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [May 6, 2000, 6:47pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/4 "2000-05-06T18:47:08Z")
I meant to put millimeters in boldface to highlight the fact that blood flow in the capillaries is **much** slower than in the arteries or veins. The velociy in the larger arteries of the dog during rest is from 0.1 to 0.2 **meter** per second, in the capillaries about 0.5 **milli** meter per second, and in the medium sized and large veins from 0.06 to 0.2 **meters** per second. ---
**Author:** ![Breckinshire](https://avatars.discourse-cdn.com/v4/letter/b/71c47a/32.png) [@Breckinshire](https://boards.straightdope.com/u/Breckinshire)\ **Post date:** [May 6, 2000, 6:52pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/5 "2000-05-06T18:52:51Z")
Exactly what I was looking for. Thanks a lot, guys. You can kick Jeeves ass any day! Hmm… AssJeeves? ---
**Author:** ![TheUnforgiven](https://avatars.discourse-cdn.com/v4/letter/t/e480ec/32.png) [@TheUnforgiven](https://boards.straightdope.com/u/TheUnforgiven)\ **Post date:** [May 6, 2000, 7:35pm UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/6 "2000-05-06T19:35:39Z")
> [@](#): > > \*\* > When the heart expands (heretofore known as expansion :)), it sends blood (heretofore known as “metallic tasting red stuff”) through the body (heretofore known as **\** ). > > \*\* Actually, blood is sent through the body when the heart (specifically, the ventricles) contracts. This is known as systole. ---
**Author:** ![Breckinshire](https://avatars.discourse-cdn.com/v4/letter/b/71c47a/32.png) [@Breckinshire](https://boards.straightdope.com/u/Breckinshire)\ **Post date:** [May 7, 2000, 6:04am UTC](https://boards.straightdope.com/t/how-fast-is-blood/18767/7 "2000-05-07T06:04:31Z")
Yes, of course, you are correct. I shall hang my head in shame and play Nintendo the rest of my life for making such an obvious, dumb mistake ☹