Guessing a hat size if someone only knows the inside diameter?

[Doc Glockster]

I keep seeing some rare hats on Ebay that I want, and it seems like invariably in listings like that the tag is missing. More often than not, the seller will take a measurement of the diameter inside the sweatband.

Is there a "pretty accurate" way to guess the hat size if you know the inside diameter?

 

[Maj.Nick Danger]

Here is one of many size charts that will give you a general idea. http://villagehatshop.com/content/38/how-to-determine-your-hat-size.html
To be more accurate, measure your own head with a tape measure just above your ears where your hat should rest, and compare to the given measurements for a particular hat.

 

[Baron Kurtz]

Not from the diameter, no, as the inside of the hat is not a circle, and the "diameter" is different at almost every point you measure it. Only the front to back is the diameter of the particular sphere formed by the sweatband.

What you need is front to back diameter and side to side "diameter" of the sweatband-bounded hole. Then compare to a hat that fits you.

I'm sure someone, somewhere, will have tabulated all the front to backs and side to sides of various different hat sizes.

 

[HudsonHawk]

Here is one of many size charts that will give you a general idea. http://villagehatshop.com/content/38/how-to-determine-your-hat-size.html
To be more accurate, measure your own head with a tape measure just above your ears where your hat should rest, and compare to the given measurements for a particular hat.

This is using the circumference of the hat, not the diameter. As pointed out below, hats are not round, so they don't really have a single"diameter", and the distance across is going to vary, depending on the point at which it's measured.

As for a hat on ebay, is is possible to ask the seller for a measurement of the circumference? That would be a much better estimate of the true hat size.

 

[Alive'n'Amplified]

I'm 7 1/4 LO. Many of my hats are approx 7 7/8 x 6 1/2. The width will be smaller if you're a long oval. Some other hats are 6 3/8 wide.




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[HudsonHawk]

I'm sure someone, somewhere, will have tabulated all the front to backs and side to sides of various different hat sizes.

If the hat were a true ellipse, it's possible to calculate the circumference, and subsequently the hat size, from the front-to-back and side-to-side measurements (the transverse diameter and conjugate diameter). But a well worn hat is more oval than elliptical, so it's probably a crap shoot as to where they take the measurements.

 

[Doc Glockster]

If the hat were a true ellipse, it's possible to calculate the circumference, and subsequently the hat size, from the front-to-back and side-to-side measurements (the transverse diameter and conjugate diameter). But a well worn hat is more oval than elliptical, so it's probably a crap shoot as to where they take the measurements.

I have also read (maybe here?) that when you measure the inside of a hat you have to allow for that hat to be slightly bigger than your head in order to scrunch down over your skull. In other words, if your head is 23" then your hat will be slightly bigger than 23" in order to fit.

 

[hatsRme]

Here's an approach that I have successfully used...

http://www.cleavebooks.co.uk/scol/callipse.htm

An Ellipse calculator, using the long (major) and short (minor) dimensions will calculate the peripheral measurement.

 

[TheDane]

But a well worn hat is more oval than elliptical, so it's probably a crap shoot as to where they take the measurements.

Exactly! There's even a seller on The Bay who refuses to measure the circumference. Instead he'll give you the length of the two axes and claims you should use an online ellipse calculator. That is "the scientific approach", he claims ... NOT!

A head (or a hat) almost never comes even close to a mathematically defined figure. An oval is not a geometric figure with a well defined formula and can have a multitude of different shapes. The circle and the ellipse are well defined geometric figures - the oval is not.

On top of that, a head (or a hat) is very often shaped in a very "autonomous" fashion. "A dented egg" will in many cases be a lot better description of the shape. In any event, there is no (simple and straightforward) mathematical formula/expression that covers the shape a head/hat.

As others have already stated: The circumference will always give you the accurate size ... nothing else will.

Here's an approach that I have successfully used...

Charlie I'm afraid, it's a coincidence that it has worked for you. Very often it will give a wrong result

 

[HudsonHawk]

All of these challenges reinforce why I personally don't buy hats that I haven't tried on. Even very small differences in measurements and shape can affect how comfortably the hat fits.

 

[fedoracentric]

The truth of the matter is that a circumference helps a lot as to determining if the hat *might* fit. But I prefer having the seller give me an ear-to-ear measurement and then a front to back measurement because that way I can be a bit more sure of the proper circumference than if the seller tries to measure it himself. Reason being it is very, very hard to measure the oval inside a hat. Most people will never get it right because it is so hard to do the measurement.

But the fact is, we need a circum. as well as a photo of the size tag and the re-order tag inside the hat. As a buyer buying blind over the internet, the only way is to have as many points of reference as possible and even then you are rolling the dice.

I mean, I've had hats marked 7-1/4 fit my 7-1/8 head perfectly. I've had hats marked 7-1/8 fit like a cooking pot. I've had 6-7/8 marked hats fit perfectly. I've had size 7 hats fit well and others that don't.

No matter how many measurements or photos you get you are still taking a shot in the dark. But all those points of reference help.

If a seller doesn't have all in his auction, best to ask.

 

[TheDane]

All of these challenges reinforce why I personally don't buy hats that I haven't tried on. Even very small differences in measurements and shape can affect how comfortably the hat fits.

In theory you're probably right, but that would keep me and a lot of other Europeans from buying anything else but contemporary factory hats. Be happy, you belong to an exclusive and privileged group of hatwearers

 

[g.durand]

The truth of the matter is that a circumference helps a lot as to determining if the hat *might* fit. But I prefer having the seller give me an ear-to-ear measurement and then a front to back measurement because that way I can be a bit more sure of the proper circumference than if the seller tries to measure it himself. Reason being it is very, very hard to measure the oval inside a hat. Most people will never get it right because it is so hard to do the measurement.

But the fact is, we need a circum. as well as a photo of the size tag and the re-order tag inside the hat. As a buyer buying blind over the internet, the only way is to have as many points of reference as possible and even then you are rolling the dice.

I mean, I've had hats marked 7-1/4 fit my 7-1/8 head perfectly. I've had hats marked 7-1/8 fit like a cooking pot. I've had 6-7/8 marked hats fit perfectly. I've had size 7 hats fit well and others that don't.

No matter how many measurements or photos you get you are still taking a shot in the dark. But all those points of reference help.

If a seller doesn't have all in his auction, best to ask.

Very well put, fedoracentric. Another variable is asking a seller for any of these measurements and trusting they know how to do it, read the tape properly, etc. I have bought a number of hats online where the measurements were given only to find them to be incorrect when I received the hat.

 

[HudsonHawk]

In theory you're probably right, but that would keep me and a lot of other Europeans from buying anything else but contemporary factory hats. Be happy, you belong to an exclusive and privileged group of hatwearers

Well, I'm not particularly interested in buying "vintage" hats, anyway, but I understand your point. I recognize that my quirk means I probably miss out on many a good opportunity.

 

[John Galt]

"Faint hat never won fair lady."

 

[fedoracentric]

Well, I'm not particularly interested in buying "vintage" hats, anyway, but I understand your point. I recognize that my quirk means I probably miss out on many a good opportunity.

Actually, your strategy is perfect if all you want is fit. In fact, this is what everyone used to do back in the olden days of yore... they'd go to a hat store and buy one that fits right.

Unfortunately, I find new hats to lie outside my interests. I only like vintage. I've bought several new hats and none of them satisfied me. So, that forces me into the crap shoot that is buying blind on ebay or other auction sites and hence into the strategy I outlined above.

 

[alanfgag]

Getting a useful measurement of the inside perimeter of the sweatband is next to impossible. Most wearers will be very sensitive to a perimeter variance of 1/4" or less. The difference in perimeter measured (accurately) at the reed end of the sweat vs. deeper within the crown will be greater than this. A graph of supplied measurements by good ebay sellers for a size 7 hat might show a range between 21 1/4 and 22 1/2 and everywhere in between. In my experience, a consultation of your horoscope is a more useful tool for predicting a successful fit.

 

[tonyb]

Getting a useful measurement of the inside perimeter of the sweatband is next to impossible. Most wearers will be very sensitive to a perimeter variance of 1/4" or less. The difference in perimeter measured (accurately) at the reed end of the sweat vs. deeper within the crown will be greater than this. A graph of supplied measurements by good ebay sellers for a size 7 hat might show a range between 21 1/4 and 22 1/2 and everywhere in between. In my experience, a consultation of your horoscope is a more useful tool for predicting a successful fit.

Yup.

 

[TheDane]

A Danish author once wrote something like: "Life starts breathing when you dare risk it". I'm a chicken so I never risk my life on purpose - but all the best things life has brought me, happened because I took a chance and jumped into something more or less unknown. A predestined life with no risk-taking would have bored me to death many years ago [huh]

 

[Art Fawcett]

In my opinion the best way of determining a true size is to find the right band block that slips into the hat nicely, then measuring the block. Measuring circumference with only a soft tape is anything BUT accurate. Whether the hat fits you is another subject because of head shape.