You’ve probably seen the price of gold flashing on a news ticker or a banking app and thought about buying a little for yourself. Maybe a small coin or a tiny bar to tuck away for a rainy day. But then you look at the specs and see "troy ounce" instead of just "ounce."
Honestly, it’s a bit of a head-scratcher if you aren't used to it. Most of us think an ounce is an ounce. You go to the grocery store, buy a 16-ounce steak, and that’s a pound. Simple, right?
Well, not in the gold world. If you try to weigh your gold on a standard kitchen scale, you’re going to be very confused, and potentially very underpaid if you're trying to sell it.
How many grams in a troy ounce of gold anyway?
Basically, there are 31.1034768 grams in one troy ounce of gold.
Most people just round that to 31.1 grams.
If you compare that to a "regular" ounce (the kind used for sugar, mail, or that steak we mentioned), which is exactly 28.35 grams, you’ll notice the troy ounce is about 10% heavier. It doesn’t sound like much until you realize that at today’s prices, that 2.75-gram difference is worth a couple of hundred bucks.
The "regular" system we use for everything else is called the Avoirdupois system. It’s a mouthful, I know. But gold doesn’t play by those rules. It uses the troy system, which is a specialized weighing method specifically for precious metals like gold, silver, and platinum.
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Why does gold use such a weird measurement?
It’s all about history. Kinda cool, actually.
The name comes from Troyes, France. Back in the Middle Ages, Troyes was a massive trading hub. Merchants from all over the world would meet there to swap goods. Because everyone was coming from different places with different "standard" weights, they needed one system they could all agree on so nobody got cheated.
They settled on the troy ounce.
By the time the 1500s rolled around, King Henry II of England made it the official standard for gold and silver coins. The U.S. eventually followed suit in 1828 because they needed to stay in sync with the British for international trade. We’ve just never stopped using it since.
The "Pound" Trap
Here is where it gets really weird and honestly a little annoying.
In our everyday system, there are 16 ounces in a pound.
In the troy system? There are only 12 troy ounces in a troy pound.
So, a funny riddle people in the industry like to tell is: Which weighs more, a pound of feathers or a pound of gold?
The answer is the feathers.
Because a standard pound of feathers is about 453 grams, but a troy pound of gold is only about 373 grams.
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However, if you ask which ounce weighs more, the gold wins every time.
The Math: Converting for your own stash
If you’re sitting on some scrap gold or a few coins, you need to know how to do the math yourself so a dealer doesn't take advantage of your "lack of expertise."
Let's say you have a gold bar that is labeled in grams—maybe it's a 50-gram bar. To figure out how many troy ounces that is, you just divide by 31.1.
- 50 grams / 31.1035 = 1.607 troy ounces
If you have it the other way around—say, a 1/4 oz gold coin—you multiply.
- 0.25 troy oz x 31.1035 = 7.775 grams
Why purity changes everything
Don't forget that "gold weight" and "pure gold content" aren't always the same thing.
Take the American Gold Eagle. It’s a 1 oz gold coin. But if you put it on a scale, it will actually weigh 33.93 grams.
Wait, what?
The coin contains exactly one troy ounce (31.1g) of pure gold, but the U.S. Mint adds a little bit of silver and copper to make it harder and more durable. If it were pure gold, you could literally dent it with your fingernail.
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On the flip side, something like a Canadian Maple Leaf or a Buffalo is 24-karat gold. Those will weigh exactly 31.1 grams because they don't have those extra alloys.
What to look for when buying or selling
If you're looking at a listing on eBay or a local classifieds site and it just says "1 oz gold bar," you better ask for clarification. Shady sellers (and sometimes just uninformed ones) might use a standard 28.35g ounce.
Reputable dealers like The Royal Mint, APMEX, or Bullion Exchanges will always use troy ounces. It's the industry language.
Real-world check:
- Check the Scale: If you’re at a jewelry store or a pawn shop, look at the scale. It should have a setting for "oz t" (troy ounces) or "g" (grams). If they are weighing your gold in "oz" (regular ounces) and paying you the troy price, they are essentially keeping 10% of your money.
- Pennyweights: Sometimes jewelers use pennyweights (dwt). There are exactly 20 pennyweights in a troy ounce. So, 1 pennyweight is about 1.55 grams. It’s an old-school way of measuring, but it’s still common in repair shops.
- The 31.1 Rule: Just memorize the number 31.1. It’s the easiest way to protect your wallet.
Practical steps for your gold journey
If you’re serious about holding gold, the first thing you should do is buy a small digital scale that features multiple units of measure. You can find them for twenty bucks online. Make sure it specifically lists ozt (troy ounce) and not just oz.
When you get your gold, weigh it immediately.
Even if it’s a sealed bar from a famous refinery, knowing the exact gram weight helps you verify it hasn't been tampered with. A 1 oz PAMP Suisse bar should weigh 31.1 grams. If it weighs 28 grams, it's a fake or it's a "standard" ounce, and you've been shortchanged.
Always verify the spot price of gold in grams if you're dealing with jewelry. You can find the live price per gram by taking the current troy ounce spot price and dividing it by 31.1035. This gives you a baseline so you know exactly how much the raw metal is worth before any "craftsmanship" or "brand" markups are added.