# how can I weigh my own head? **URL:** \ **Category:** Factual Questions\ **Created:** [May 27, 2006, 9:54am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431 "2006-05-27T09:54:25Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![V\_neef\_Massoud](https://avatars.discourse-cdn.com/v4/letter/v/a3d4f5/32.png) [@V\_neef\_Massoud](https://boards.straightdope.com/u/V_neef_Massoud)\ **Post date:** [May 27, 2006, 9:54am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/1 "2006-05-27T09:54:25Z")
can somebody think of a easy way of determining the weight of my head ? without removing it from the neck ---
**Author:** ![gabriela](https://avatars.discourse-cdn.com/v4/letter/g/db5fbb/32.png) [@gabriela](https://boards.straightdope.com/u/gabriela)\ **Post date:** [May 27, 2006, 10:13am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/2 "2006-05-27T10:13:27Z")
I can’t weigh your head, but I can tell you what a human head weighs once it is disconnected from the neck. Ten pounds. I work in forensics and we occasionally get a body in which, er, circumstances have separated the head from the rest. We weigh it. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [May 27, 2006, 11:39am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/3 "2006-05-27T11:39:33Z")
But what if you died pondering weighty subjects? 🙂 But really, if you lie down on the ground and rest your head on a measuring thing, that should be pretty close once you have relaxed for a while. Of course you will need someone else to watch the meter. And of course if it isn’t around ten pounds, then I guess we know that this method doesn’t work. ---
**Author:** ![Wallenstein](https://avatars.discourse-cdn.com/v4/letter/w/b5a626/32.png) [@Wallenstein](https://boards.straightdope.com/u/Wallenstein)\ **Post date:** [May 27, 2006, 12:36pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/4 "2006-05-27T12:36:23Z")
Get a bucket. Weigh it. (x) Fill it with water. Weigh it again. (y) Put your head in the bucket. Remove your head. Weigh the bucket. (z) (y-x) - (z-x) = your head The human head is mostly brain. Brain is mostly water. Water has a density of 1kg per litre at 4C. So the amount of water displaced is (give or take) the weight of your head. (The average male head weighs 4.25kg) ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [May 27, 2006, 12:40pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/5 "2006-05-27T12:40:24Z")
> [@V'neef Massoud](#): > > can somebody think of a easy way of determining the weight of my head ? without removing it from the neck Would this do the job? 1. Draw a line around your neck at the point where it leaves off and your head begins. 2. Plug you nostrils and be suspended over a tank of water with a scale in the suspension line. 3. Take weight in air. 4. Be lowered into the water up to the line. 5. Take weight with head in water and measure the water displaced. 6. Calculate. So maybe not as easy as others suggested but more accurate. ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [May 27, 2006, 12:54pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/6 "2006-05-27T12:54:55Z")
Ah, the “how can you weigh a head?” quagmire … About 15 years ago the Notes & Queries column in the Guardian carried this question. (N & Q is a sort of low-grade version of GQ; they don’t put the newspaper version online, but they do have [a similar section on their website](http://www.guardian.co.uk/notesandqueries/0,,184276,00.html).) This prompted a long-running heated debate over multiple morning coffees in the theoretical physics group where I was a grad student at the time. Several of those who chipped in were FRSs. The result: “how can you weigh a head?” became the department’s stock joke example of a simple physics question that nobody can agree on. Several obvious possible answers were quickly deemed unsatisfying. **Sage Rat** ’s suggestion will quite possibly give a reasonable experimental result, but there’s the feeling that it’s an example of essentially appealing to the head being _effectively_ disconnected under particular conditions. However, the big obstacle that you keep running up against is density variations. For instance, as the other posts have recognised, the problem is trivial if we assume that the human body is of uniform density throughout: measure the overall weight and volume and then the volume of the head. Again, this assumption may be good in practice, but there was the counter-argument that this is just an accident of the circumstances. Generalise the problem to arbitrary distributions of mass with arbitrary shape, with the human body and its head as a special case, then these sorts of assumptions become useless. What was interesting - and part of the reason the debate got quite heated at times - was that even professional physicists could get rather entrenched in incorrectly arguing that their current suggestion - usually involving levers and buckets of water - managed to avoid these assumptions. Naturally, people then appealed to X-rays and the like. (I think it was me who jokingly suggested gravitational lensing.) These methods can certainly get a handle on the density variations, but nobody ever managed to construct an elegant method that was _obviously_ able to answer the general question. Some of us did wind up conjecturing that there was some impossibility theorem along the following lines: given an arbitrary rigid mass there’s no mechanical method of determining the mass on one side of an arbitrary plane. But nobody ever bothered trying to formalise this. Of course, this was a bunch of theorists arguing. Though it’s an interesting example of how in certain circumstances theoretical physicists will happily simplify a problem to get an answer, while in others they will argue that making a similar assumption - while maybe reasonable in practice - misses the interesting version of the problem. ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [May 27, 2006, 1:30pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/7 "2006-05-27T13:30:27Z")
Have a spring connected to a newton meter on one end and your head on the other. Record the force downwards suspended in mid air and then the force downward with your head dunked in water. Based on the difference of the two, it should be possible to work out how bouyant your head is and , along with the displacement, how much it weighs. ---
**Author:** ![Beware\_of\_Doug](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)\ **Post date:** [May 27, 2006, 1:53pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/8 "2006-05-27T13:53:26Z")
> [@e-logic](#): > > Get a bucket. > > Weigh it. (x) > > Fill it with water. > > Weigh it again. (y) > > Put your head in the bucket. > > Remove your head. > > Weigh the bucket. (z) > > (y-x) - (z-x) = your head > > The human head is mostly brain. Brain is mostly water. Water has a density of 1kg per litre at 4C. > > So the amount of water displaced is (give or take) the weight of your head. > > (The average male head weighs 4.25kg) And if you have a few apples, you can weigh them, subtract the total from the equation and BOB FOR APPLES! 😃 ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 27, 2006, 2:52pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/9 "2006-05-27T14:52:53Z")
> [@e-logic](#): > > Get a bucket. > > Weigh it. (x) > > Fill it with water. > > Weigh it again. (y) > > Put your head in the bucket. > > Remove your head. > > Weigh the bucket. (z) > > (y-x) - (z-x) = your head > > The human head is mostly brain. Brain is mostly water. Water has a density of 1kg per litre at 4C. > > So the amount of water displaced is (give or take) the weight of your head. > > (The average male head weighs 4.25kg) Someone can perhaps correct me on this, but I was under the impression that a considerable proportion of the bran was composed of fat. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 27, 2006, 2:53pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/10 "2006-05-27T14:53:55Z")
**Brain** :smack: obviously _bran_ isn’t made of fat. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [May 27, 2006, 3:06pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/11 "2006-05-27T15:06:23Z")
I don’t know if this thread is apporopriate for GQ: calling people fat-heads and telling them to go stick their heads in a bucket. Since the skull has some substantial air pockets too (sinuses, airways and esophagus) my guess is that that lowers density even farther. ---
**Author:** ![Wallenstein](https://avatars.discourse-cdn.com/v4/letter/w/b5a626/32.png) [@Wallenstein](https://boards.straightdope.com/u/Wallenstein)\ **Post date:** [May 27, 2006, 4:01pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/12 "2006-05-27T16:01:22Z")
I took my info from the New Scientist - they were asked the same question and that’s the method they suggested. Weighing a head will never be easy as it’s attached to the rest of the body - finding the volume and then using average compositional data is probably the nearest you’re gonna get from a home experiment. ---
**Author:** ![Wallenstein](https://avatars.discourse-cdn.com/v4/letter/w/b5a626/32.png) [@Wallenstein](https://boards.straightdope.com/u/Wallenstein)\ **Post date:** [May 27, 2006, 4:10pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/13 "2006-05-27T16:10:42Z")
> [@Mangetout](#): > > **Brain** :smack: obviously _bran_ isn’t made of fat. Intracranial contents by volume \*\*Whole Brain (1,700 ml, 100%): \*\* brain = 1,400 ml (80%); blood = 150 ml (10%); cerebrospinal fluid = 150 ml (10%) (from Rengachary, S.S. and Ellenbogen, R.G., editors, Principles of Neurosurgery, Edinburgh: Elsevier Mosby, 2005) Composition of Brain **Whole Brain (%):** Water 77 to 78 Lipids 10 to 12 Protein 8 Carbohydrate 1 Soluble organic substances 2 Inorganic salts 1 (Reference: McIlwain, H. and Bachelard, H.S., Biochemistry and the Central Nervous System, Edinburgh: Churchill Livingstone, 1985) (Just need the proportion of the head that the skull makes up…) ---
**Author:** ![ratatoskK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ratatoskk/32/2987_2.png) [@ratatoskK](https://boards.straightdope.com/u/ratatoskK)\ **Post date:** [May 27, 2006, 4:14pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/14 "2006-05-27T16:14:40Z")
Can’t you just lie down with your head on a scale? ---
**Author:** ![Annie-Xmas](https://avatars.discourse-cdn.com/v4/letter/a/ecc23a/32.png) [@Annie-Xmas](https://boards.straightdope.com/u/Annie-Xmas)\ **Post date:** [May 27, 2006, 4:22pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/15 "2006-05-27T16:22:11Z")
> [@V'neef Massoud](#): > > can somebody think of a easy way of determining the weight of my head ? > > without removing it from the neck Find someone of a similar build and head size as your own. Remove _their_ head. Weigh it. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [May 27, 2006, 5:01pm UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/16 "2006-05-27T17:01:44Z")
As others have mentioned using water diplacement to measure volume and assuming that the body has a uniform density is the easiest. I don’t know how close to the real answer you will get using this method, though I imagine it would be good enough for government work… Could something be done with moments of inertia? Stand on a freely rotating like a mery go round. Measure the rotation speed. Tilt your head forward known amount. Measure change in rotation speed. Repeat. Do lots of numerical simulations/integrations changing head mass parameter until the data matches the experiment. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 28, 2006, 1:32am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/17 "2006-05-28T01:32:57Z")
> [@e-logic](#): > > Intracranial contents by volume > \*\*Whole Brain (1,700 ml, 100%): \*\* > brain = 1,400 ml (80%); > blood = 150 ml (10%); > cerebrospinal fluid = 150 ml (10%) > > (from Rengachary, S.S. and Ellenbogen, R.G., editors, Principles of Neurosurgery, Edinburgh: Elsevier Mosby, 2005) > > Composition of Brain > **Whole Brain (%):** > Water 77 to 78 > Lipids 10 to 12 > Protein 8 > Carbohydrate 1 > Soluble organic substances 2 > Inorganic salts 1 > > (Reference: McIlwain, H. and Bachelard, H.S., Biochemistry and the Central Nervous System, Edinburgh: Churchill Livingstone, 1985) > (Just need the proportion of the head that the skull makes up…) Hmmm… I can’t cast doubt on your cite of obvious authority, however, I’m surprised the percentage of fat is so low; I’m reading in lots of different places (none of which I feel particularly worthy of citing here, and all of which may be simply quoting each other) that the brain is composed of 60% structural fat. ---
**Author:** ![Askia](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Askia](https://boards.straightdope.com/u/Askia)\ **Post date:** [May 28, 2006, 1:37am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/18 "2006-05-28T01:37:14Z")
Oh, Cecil… ---
**Author:** ![robardin](https://avatars.discourse-cdn.com/v4/letter/r/43a26b/32.png) [@robardin](https://boards.straightdope.com/u/robardin)\ **Post date:** [May 28, 2006, 4:22am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/19 "2006-05-28T04:22:04Z")
I don’t get it. As **ratatoskK** also asked, why can’t you just do something equivalent to lying on a couple of gym mats stacked to about a foot’s height with your neck on the edge, and putting your head on a plate resting on a scale? WTP? ---
**Author:** ![Klaatu](https://avatars.discourse-cdn.com/v4/letter/k/e0b2c6/32.png) [@Klaatu](https://boards.straightdope.com/u/Klaatu)\ **Post date:** [May 28, 2006, 4:48am UTC](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431/20 "2006-05-28T04:48:32Z")
Well, a cursory google of “weight of a human head” shows some answers of 4 to 6 kilograms, which appears to somewhat agree with Gabriela. If you go through the results, they pretty much end up at a ballpark figure of around 10-12 pounds. [Next page](https://boards.straightdope.com/t/how-can-i-weigh-my-own-head/358431.md?page=2)