What is a Troy Ounce? Troy vs. Avoirdupois Weight, Weighing Precious Metals

by Mike Unser on July 22, 2007 · 24 comments

Since many coins contain a precious metal, we expanded our website to include charts and spot prices of silver, gold and platinum (found here). In doing so, I was reminded of a common misconception many people have regarding the system of weight for precious metals. Many think an ounce of gold is the same “weight” as an ounce of beef. It’s not!

Troy vs. Avoirdupois Weighing System is completely different.

When you step on the scale, you don’t think of it but what’s being measured uses the system of weight known as avoirdupois. If we’ve lost a few pounds, we’d say something like, “I lost 2 pounds!” We wouldn’t say, “I lost 2 avoirdupois pounds!”

We’ve used the avoirdupois weight system in every day use for so long that we don’t even use its silly-seeming name. We can even break the system down. For example, most of us know there are 16 ounces in a (avoirdupois) pound.

What many don’t know or fail to remember is that silver, gold, platinum and other precious metals use the troy weight system. It’s completely different. When comparing the two systems – apples to apples – a troy ounce is heavier than an avoirdupois ounce – about 10 percent more. Or, more clearly, 10 troy ounces or 10 American Silver Eagles weigh more than a 10 ounce cut of steak.

Yet, and this is what can add to the confusion or what is often times forgotten, one troy pound weighs less than one avoirdupois pound. What… How!? Well, that’s ONLY because a troy pound has its own definition. One troy pound is defined as having 12 ounces – not the 16 ounces as defined in an avoirdupois pound.

This table may be useful:
 

 

Metric Weight

# Ounces as Defined per Pound

Use in Weighing

Troy ounce

31.10 grams

12

Precious metals, gemstones, etc.

Avoirdupois ounce

28.35 grams

16

Every day items

Knowing how coins containing silver, gold or platinum stack up against our "every day" weight system isn’t super critical for a collector. But it doesn’t hurt either! Especially when so many collectible coins these days contain a precious metal.

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Edwin Davis
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Edwin Davis

Mine is more question than comment. I have some twenty four carat gold pendants and some gold chain in twenty four carat, is this considered pure gold? and would it best be melted down into bullion or not? Also, how can one be assured of getting fair assesment and price when selling by mail??

Herbert Levinson
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Herbert Levinson

1/12, of a smaller tory pound. If you measure it out it on a advoc scale as a twelvth, or a mniscalibration designed to defraud and befuddle the unaware dupe.

You know if you have precious metals or jewels. You should look at that as regular money. But, with slightly less fluitity than dollars. But usually rising in value at this time, in an unsecure state of our economy. that’s because its more tangleable than paper dollars. But, a little less negociable for trade. But, wise to retain for future value assendance.

Look that’s why we are always harangued and beseached on TV about selling our broken jewelry. Its become more valuable, as a metal than the bobble it adorns. Gold is necessary in electronics and so is silver. Not to mention copper and others sodium etc.

juan
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juan

Hi,everyone.
So, when a person weights gemstone and metal together it should be counted as a troy. I understand the density, “steak and metal” table. Thanks for clearing that up. lol smile But how can i determine, the price for gemstones?.

Kirk
Guest
Kirk

Heh, heh.
This is exactly why I love asking people the riddle, “Which weighs more, a pound
of feathers or a pound of gold?”
They invariably say they both weigh the same but pointing out that the feathers
actually weigh more and explaining why is a kick!!

John Jessey
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John Jessey

Hi i have 4pounds of old and it is a 22carat gold, how much is this in dollars if i sell it? . thanks

Jon White
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Jon White

Edwin, and anyone else considering selling precious metals by mail. Steer clear of places such as Cash for Gold and the like – If you want a decent service, a fast turn around and a very fair price, then you can’t go wrong with Northern Refineries. http://www.northernrefineries.com – I recently sent a bag of scrap silver I had collected over a number of years. I got a check back for 90% of the current silver market price within 5 business days. I did a lot of research on this subject beforehand and Northern Refineries came out miles ahead of anyone else.

vic
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vic

Sorry you are wrong. It isn’t 12 troy but 14.583 to the pound and that’s how they make an edge with selling and buying ( I was a PM refiner for 22 + years.)

Larry
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Larry

Bottom line, for those who can not figure apples to oranges into apples to apples
How many Avoirdupois ounces does it take to make one Troy ounce? 1.1? 1.10259? or what ever, just so one can make quick estimate of a Troy ounce, and understand the TV news person when they say an ounce of gold is trading at $xxxx. (I’m assuming they are talking about Troy ounces) in their quoting.
I do not need 6 – 10 decimal points, just 2 or 3 rounded off would be fine.
Thanks, this will enable me to judge a little better.

bob
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bob

The comments on this page show how well these people DO NOT understand, a pound is a pound, the grams are of 1/28 or 1/31 roughly.

Kirk
Guest
Kirk

bob,
A pound troy is not a pound avoirdupois. Read the above again. Then read this: http://www.troy-ounce.com/
While a troy ounce is heavier that an ounce av., with there being more ounces in an av. pound, the av. pound weighs more that a troy pound since the ounce difference is not great enough to overcome the extra amount.
Figure it in grams, figure it in grains….still the same result.
Thanks for keeping this thread alive, though!

Larry
Guest
Larry

Simple math, gets you close, 1.1 av. oz. = 1 troy oz. of 24k gold. understood.
Question: Using the above… would the following be correct?
Estimate any item’s value. Less than 24k it’s a % of 24K. An 18k ring = 18/24 = 75% (.7500) times gold prices quoted. Ring, wt. 2.2 av. oz. / 1.1 = 2 troy oz. (of 24k pure gold) so 2 troy oz. times .75 (% of pure gold) = 1.5 troy oz., which then is multiplied by the gold price, say it’s $1,200/troy oz., and ring @ 1.5 “troy oz” would equal $1,800.00? TIME TO SELL THE FARM, MABLE! (joke ha ha ha)

Manny
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Manny

My question. I have exactly $14.00 Face of Walkers, or 28 coins. I asked a local coin dealer how much it was worth or actually how much was he willing to pay. He quoted me 21 x Face. At the time silver was going for $34 +/- .
Where do they get the 21 or 24 etc x face. Silver calculators came up with a higher price than was offered.
Also have 10 1oz (troy) of sterling silver (925). I am a firm beleiver that they should make a profit.

RFR
Guest
RFR

If you divide the silver spot price by $1.38, that will give you the Times Face figure with which you can calculate the worth of any 90% US silver coin just knowing the Face amount and a simple multiplication with the Times Face figure.

Most people who buy silver, and resell silver, buy at a price level below the days spot price to give themselves a profit when they resell. As an example, if the days spot price is $41.40 a division by $1.38 gives you a Times Face figure of 30. So, if someone has $3.15 worth of silver to sell it is a simple multiplication of 30×3.15=$94.50. I usually try to buy two levels below the spot price, which in this example would be 28x. This gives me a margin of profit and a margin of safety if the market for silver goes down.

Mike
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Mike

Sorry, Vic, but you are the one who is wrong.

There are indeed 14.583 Troy ounces to the Avoirdupois pound but there are only 12 Troy ounces to the Troy pound.

Kevin
Guest
Kevin

How many troy oz in a tonne? How many troy lbs. in a tonne? When they refer to tons(tonnes) of gold on hand, is that a troy tonne or a metric tonne? I can’t seem to find a conversion chart to print out, but do not want a” calculator”. Kevin

Robert
Guest
Robert

I have a 2 pound chunk of silver that was various silver coins that was melted when my house burned because they weren’t in a fireproof container. How much is it worth? They were nickels, dimes, quarters, half dollars, and dollars can’t remember exactly what ones or how many of each.

Geoffrey
Guest
Geoffrey

Seems a lot simpler to just use grams….

Mike
Guest
Mike

So what weighs more an ounce of gold, or an ounce of feathers? And the next time that someone says the ounce of gold, ask which weighs more a pound of gold, or a pound of feathers?

Pablo Varela
Guest
Pablo Varela

There is a method to all this madness after all… When all is said and done, 31.10 grams weighs more than 28.35 grams… we can all agree to this?

Shawn
Guest
Shawn

Great read here! I knew nothing of the differences between the two measurement systems before I read this, and after extensive research I must say….YES, You are 100% Correct!!!
1 Troy oz= 31.10 grams or 480 grains
1 Avoirdupois oz= 28.35 grams or 437 1/2 grains
making the Troy oz 10% heavier than the Avoirdupois oz when compared side by side with grams and grains.
Also,
12 Troy oz= 1 Troy pound (373.24 grams or 5,760 grains)
Just to be clear, today, the Troy systems of measuring weight is generally used only with precious metals and gemstones, Avoirdupois system is the everyday standard weight measuring system used in most parts of the world.

Adahn
Guest
Adahn

@Shawn >>Avoirdupois system is the everyday standard weight measuring system used in most parts of the world.<<<
If most parts of the world means Myanmar, Liberia and the US then you're right.
The rest of the world uses the more logical metric system where a gram is a gram and 1000g of water is one Liter that fits into a cube of 10×10 cm. And this water is turning into ice at zero degrees and boiling at 100 degrees.
What a strange system says the American…

sam
Guest

Adahn, one 1L fits into 1000 cubic centimeters (or cc’s) not 100 (10×10) (most parts of the world use the S.I. (metric) system not the so-called “Imperial, commonly used U.S. system” as these vary even in different countries and have fallen into disuse. For healthcare the S.I. system is used and safest imho given that patients may travel and it facilitates the communication and enhances the precision with minimal error. Remember when they tried to land that space thing on Mars (the first one) it had crashed bc someone used 5 miles as a calculation instead of 5 km for it’s landing, basically it boiled down to an error bc of not using the same system between different scientists. good idea to have only one official system of measurement, but it seems to me that errors of this nature almost fall in favor to the common US measurements especially when… Read more »

sam
Guest

addendum:

not that there is an error in L and gallons of gas, but can you see how confusing it is? it’s accurate but having 2 different conceptualizations just complicates the matter and rather than keeping it simple.

Adahn
Guest
Adahn

Well, you’re right with the 1000 cc, but I never said it’s 100, I just missed a x10.
“…into a cube of 10Ă—10 cm.”
The most commonly used Imperial measurement worlwide seems to be the inch, at least when it’s about screen sizes and knife blade’s lengths…