Tool Time Tuesday – Ounce to Ounce – How does it compare?

This Tool Time Tuesday topic is one that you might find helpful and will hopefully learn some new things that will make ordering your metal a little easier.

Here in the United States we have a few different ways to measure volume and weight. Today we will be talking about measuring the weight of our metal.

When I order my metal from a given supplier, I typically order it based on the weight which is measured in Troy Ounces. When I weigh my kids or food or letters or whatever else, it is typically measured in Avoirdupois Ounces or pounds. There is a difference. Most people don’t realize that there is a system called Troy Weights. A troy ounce is more than the typical ounce (Avoirdupois) found in the grocery store. Both are made up of a smaller unit called grams. Luckily for us, a gram is a gram.

1 Avoirdupois ounce (oz) = 28.35 grams (437.5 grains)
1 Troy ounce (Toz)= 31.1 grams
1 Troy ounce – 20 pennyweights
1 Pennyweight (dwt) – 24 grains
1 grain = .06479891 grams

A Troy pound is lighter than an avoirdupois pound because it contains fewer ounces.

1 Troy pound (373.25 grams) contains 12 Troy ounces.
1 Avoirdupois pound contains 16 avoirdupois ounces.
1 avoirdupois pound is 453.6 grams (16 oz), which is the equivalent of 14.583 Troy Ounces.
1 Troy Pound is just over 13 Avoirdupois ounces.

Even through the troy ounces are heavier, the difference is not enough to make a troy pound heavier.

Gold and Silver and other precious metals are weighed with this Troy Weight system. When you buy a 1 oz coin, it is a Troy oz. If you were to put that coin on a grocery scale, you will find that it weighs about 10% more than the food (Avoirdupois) ounce that you are used to.

How much metal do you get for a given weight? Well, that entirely depends on the gauge of wire you order. As you know, thicker wires or sheets are going to weigh more than thinner ones. I really like to use a chart that lays it out nicely at
Wire Specifications

Conversion formula. If you only have a scale that weighs in Avoirdupois ounces you can easily convert that into Troy ounces with the following formula:
Multiply # regular ounces X  .912 to
get approximate # troy ounces

This came in quite handy when I was doing my inventory recently where I had to weigh my silver and then convert it into Troy Ounces to determine its value.

So where did the Troy weight system come from? It is believed to be named after Troyes, France. This is a system they developed back in the medieval times at the celebrated fair at Troyes in North Eastern France.

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