What is a Troy Ounce? Troy vs. Avoirdupois Weight, Weighing Precious Metals
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!
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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June 24th, 2008 at 2:02 pm
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??
February 23rd, 2009 at 5:12 pm
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.