Chris Telden enjoys teaching others how to apply simple mathematical operations in real-life situations. Math is power!
Here are the basic instructions for how to calculate, in pennyweight, the price of your old gold jewelry, miscellaneous gold scrap, or any other gold items that you hope to sell, whether in 10k, 14k, 18k, or other karat weights. I will walk you through five easy steps teaching you how to:
- Find the current price of gold in troy ounces.
- Convert troy ounces to pennyweight.
- Weigh the gold by karat units in grams, troy ounces, or pennyweight.
- Factor in the purity (in other words, the amount of actual precious metal versus base metal) of the gold alloy.
- Calculate the value of the gold in pennyweight. (I will be using U.S. dollars, but it's simple to convert the amount to a different currency.)
For your convenience, you can also find here a quick reference for pennyweight conversion to ounces, troy ounces, grams and grains.
When Is Pennyweight Used?
Though troy ounces have become the standard weight for reporting gold prices, pennyweight is commonly used to measure:
- dental gold such as that used in crowns and inlays
- gold jewelry
The abbreviation for pennyweight, dwt, derives from denarius, the Latin word for penny.
1. Pennyweight Conversion: Find Out the Price of Gold per Troy Ounce
Visit NASDAQ to find today's gold price per troy ounce, also called the spot price of gold.
As of April 2020, the price of gold is over $1,700, but other times it may be below $1,000 or even much higher.
But for now, as an example, let's use a nice round number and say the current gold price is $1,000 exactly.
Basic Pennyweight Conversion to Gram, Grain, and Troy Ounces
One pennyweight of gold, also called 1 dwt, equals:
- 1.555 grams
- 24 grains
- .05 troy ounces
- .055 ounces (standard)
For reverse conversion:
- 1 gram = .643 dwt
- 1 grain = .042 dwt
- 1 troy ounce = 20 dwt
- 1 standard avoirdupois ounce = 18.23 dwt
2. Convert From Troy Ounces
Use the conversion metrics in this article under the section Basic Pennyweight Conversion to Gram, Grain, and Troy Ounces to convert troy ounces to pennyweight. This will yield the gold price per pennyweight.
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This is how to do it:
We see that one troy ounce equals 20 pennyweight of gold.
So using our example, since 1 troy ounce has a current value of $1,000, then 20 pennyweight of gold is worth $1,000. But we want to know the value of 1 dwt of gold, not 20.
So we divide $1,000 by 20 to calculate the gold price per pennyweight.
In this example, the gold price per pennyweight is $50 exactly.
Now it's time to calculate the value of the gold - in other words, what your actual gold scrap or other items are worth.
3. Weigh the Gold Scrap
Sort the gold jewelry, dental gold, gold bullion, gold coins, or whatever other items you have into separate units by karat - 10k, 12k, 14k, 18k, 24k. Leave out any items that are gold plated.
Weigh each karat unit separately using a pennyweight scale. Or, if you don't have a pennyweight scale, weigh the gold in grams or avoirdupois ounces first, then convert to pennyweight units using the conversion chart in this article.
For example's sake, pretend you weigh a rather hefty lot of 18K gold jewelry on an ounce scale and find out it is 5.5 ounces avoirdupois. You then convert it to pennyweight by multiplying 5.5 times 18.23 (see the chart) and discover it is 100.265 dwt, or, rounded off, 100.27 pennyweight of gold.
Or if you have a gram scale, let's say you weigh this same lot of 18K gold and find out it is 155.92 grams. Multiply 155.92 times .643 dwt to get 100.257 dwt, or, rounded off, 100.26 pennyweight of gold.
The difference in the two examples (100.27 vs. 100.26) is due to rounding off at various points in the calculations - so understand that these numbers are close approximations only.
Let's use the results from the gram scale. You have, in this example, 100.26 pennyweight of gold.
4. Factor in the Purity of the Alloy
Did you know that most gold is not pure? Most products have base metals in them, too, like nickel, copper, zinc, and tin. The amount of actual precious metal contained in circulating gold is standardized by the karat system. Only 24 karat gold and gold bullion sold for investment purposes are mostly all gold. All other objects contain significant amounts of base metal. If you are going to sell your gold, its value depends on how pure the gold is. So you must figure out how much actual gold is in your scrap gold items.
In our example, we have 100.26 pennyweight of gold. We must multiply this number times .75 (75 percent) for 18k gold.
If we had 10k gold, we would multiply by .4167 (41.7 percent)
If we had 14k gold, we would multiply by .5833 (58.3 percent).
If we had 24k gold, or gold bullion, we would not multiply by anything (actually, we would multiply by 1, which would give the same results)
To find the percentage of other karats, such as 9k, divide the karat number by 24.
In our example, 75.195 dwt is the actual amount of gold in pennyweight.
5. Calculate the Pennyweight Value of Gold
Now it's time to multiple the pennyweight of gold by the scrap gold price per pennyweight to get the value of the scrap gold.
Multiply 75.195 dwt times $50. The result is: $3,759. That is the spot price of your 18k scrap gold lot.
If you are in the UK, Canada, Australia, or other country, convert the dollar amount to pounds, Australian or Canadian dollars, or your currency.
Note: If you are going to sell the gold to a scrap gold dealer, pawn shop, or other scrap gold buyer, then you will probably get 20 percent to 50 percent less than this, since the dealer will take a cut.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
ilitek on September 17, 2011:
really an informative for me.thanks for sharing.
Chris Telden (author) from Pacific Northwest, U.S.A. on May 24, 2010:
A jeweller you trust may be your best bet. My mother-in-law sold some gold recently to the place she buys most of her jewelery and got what I thought was a good price.
The general rule seems to be that, like everything else, you pay for convenience. If it's easy to sell it - for example, if you ship it to a precious metal buyer in one of those kits they send and get the cash mailed to you - then you're probably not getting top dollar. If getting top dollar, and not quick cash, were my first concern, then I'd establish relationships with jewellery sellers or even designers and do some serious comparison shopping - always keeping tabs on what the gold price is, watching the market to catch the times when the price was optimal, etc.
But I always think of my mother, who collected baseball cards partly as an investment. She kept thinking she'd get book price for them, but in the end learned that the only one who gets book price is the dealer. My personal axiom is: The more work and care you put into in selling anything you own of value, the more you're likely to get out of it.
JoshCooper on May 19, 2010:
Hey if selling to gold dealer, pawn shop, or other scrap gold buyer is not a gold ideal were can I go to sell my gold and get good money
microfinance from Morocco on December 15, 2009:
Chris Telden (author) from Pacific Northwest, U.S.A. on December 09, 2009:
I received a question asking for help calculating the value of 2.281 troy ounces of gold in Australian dollars.
Here is my answer, in case another example of a calculation might help anyone else:
The value depends on the date on which you're figuring it out, because the price of gold changes daily, and also on the karat of the gold - 10k, 14k, 18k, etc.
Check the price of gold online. That will be in troy ounces and, depending where you look, US$. Let's pretend the price of gold is US$1000 per troy ounce.
Now sort your gold into karat weights, Weigh each group separately. Let's say you have one group of 2.281 ounces of 14K gold.
For each group, divide the karat weight by 24, then multiply that number times the weight in ounces of the gold in that karat. In our example, this works out to 1.33 troy ounces.
That is the weight of actual gold that you have, after the other metals in the alloy are taken out of the equation.
Multiply that number times the price of gold in troy ounces that you checked earlier. So in our example, the answer would be $1,330.58.
Convert that number to Australian dollars using the day's exchange rate. And that's an example of how you get your answer.