If you sell gold jewelry, coins or other precious metals, you may hear a dealer use the term pennyweight or see the abbreviation dwt on a scale.

For people who normally think in grams, that can be confusing.

A pennyweight is simply a unit of weight used in the troy weight system. It is not a different way of valuing gold, and it does not change how much metal you have.

1 pennyweight = approximately 1.555 grams.

20 pennyweights = exactly 1 troy ounce.

What Is a Pennyweight?

The pennyweight is an old unit of measurement that became part of the traditional troy weight system used for precious metals.

The abbreviation is dwt.

The basic relationships are:

1 pennyweight = 24 grains
20 pennyweights = 1 troy ounce
1 pennyweight = approximately 1.55517 grams
1 troy ounce = approximately 31.1035 grams

The name comes from an old system in which the weight of a silver penny was used as a reference point.

Why Do Coin and Precious-Metal Dealers Use Pennyweights?

The main reason is simple: pennyweights and troy ounces work together.

Gold, silver, platinum and other precious metals are traditionally traded in troy ounces.

There are exactly 20 pennyweights in one troy ounce.

That makes the math very convenient:

5 dwt = 1/4 troy ounce
10 dwt = 1/2 troy ounce
15 dwt = 3/4 troy ounce
20 dwt = 1 troy ounce
100 dwt = 5 troy ounces

For someone who works with precious metals every day, that is an easy system to calculate mentally.

Why Not Just Use Grams?

There is nothing wrong with grams.

Many jewelers use grams because their customers are familiar with them, and grams are commonly used in retail gold jewelry.

The difference is that grams do not divide evenly into a troy ounce.

One troy ounce equals approximately 31.1035 grams.

So if the underlying gold market is quoted by the troy ounce, working entirely in grams requires an additional conversion.

Pennyweights stay inside the same troy system the precious-metals market already uses.

Do Pennyweights and Grams Give Different Results?

No.

They are simply two different ways of describing the same weight.

For example:

10 dwt = approximately 15.55 grams.

If a piece of jewelry weighs 10 pennyweights, switching the scale to grams does not change the amount of gold. The display will simply show approximately 15.55 grams instead.

The unit changes. The gold does not.

Why Can the Number on the Scale Look Smaller in Pennyweights?

This is one of the things that can confuse customers.

A customer may be accustomed to seeing a piece of jewelry listed as weighing 15.5 grams. If a dealer places it on a scale set to pennyweights, the display may show approximately 10.

Nothing has disappeared.

The scale is simply using a different unit.

It is similar to measuring the same distance in miles instead of kilometers. The number changes because the unit changes, not because the actual amount changed.

Can You Show the Weight in Grams?

Yes.

At Oakton Coins & Collectibles, we routinely work in pennyweights because that is our normal working unit for precious metals.

If a customer wants to see the weight in grams, the scale can be switched to grams.

The conversion does not affect the value, purity or actual weight of the item.

Why Can Switching to a “Price Per Gram” Make Things More Confusing?

Sometimes a customer will ask for the value of gold per gram in the middle of a transaction.

We can certainly convert it, but it does not make the calculation more accurate.

If the gold market is quoted in troy ounces and the dealer is already working in pennyweights, everything is operating within the same system.

Converting the market price into grams simply adds another mathematical step.

For someone accustomed to working in the troy system, that can actually make an otherwise straightforward calculation harder to follow.

The important thing is not whether the calculation is done in grams or pennyweights. The important things are the actual weight, the purity of the metal, and the market being used to determine value.

Is Pennyweight Used to Confuse Customers?

No.

Pennyweight is a traditional working unit in the coin and precious-metals trade because it divides evenly into the troy ounce.

Using dwt does not reduce the reported weight or change the amount of gold being evaluated.

In fact, for dealers who work primarily in troy ounces, pennyweights can make the calculations simpler and easier to verify.

Some jewelers prefer grams because that is what their customers expect to see. Coin and precious-metals dealers often continue to use pennyweights because of their direct relationship to the troy ounce.

What Does DWT Mean on a Scale?

If you see dwt on a scale, it means the scale is displaying pennyweights.

It does not mean the scale is measuring anything differently from a gram scale. Most professional scales can display the same physical weight in multiple units.

The important conversion to remember is:

1 dwt = 1.55517 grams

and

20 dwt = 1 troy ounce.