Pennyweight
Also: dwt, DWT, penny weight
The pennyweight (dwt) is a unit of mass in the troy system equal to 1/20 of a troy ounce, used above all in the Anglo-American jewellery and goldsmithing trades.
The pennyweight (abbreviation: dwt) is a unit of mass drawn from the troy weight system, a system that has been used to weigh precious metals and coins since the Middle Ages. Its name comes from the English penny: in medieval England a silver penny coin weighed exactly one pennyweight. The abbreviation dwt derives from the Latin denarius weight, the denarius being the Roman ancestor of the penny.
Conversions at a glance
| Unit | Value in dwt |
|---|---|
| 1 pennyweight (dwt) | 1 dwt |
| 1 troy ounce (ozt) | 20 dwt |
| 1 troy pound | 240 dwt |
| 1 grain | 1/24 dwt |
In metric terms:
1 dwt = 24 grains = 1/20 troy ounce ≈ 1.55517 grams
For comparison, the avoirdupois ounce (the everyday commercial ounce) works out at roughly 18.23 dwt, making it lighter than a troy ounce (20 dwt).
Use in practice and trade
Across continental Europe the pennyweight barely features; there, grams and the troy ounce rule as the standard units. The picture is different in the Anglo-American market: goldsmiths, jewellers and pawnbrokers in the United States, Canada and Australia routinely quote scrap-gold buying prices in dwt. Anyone selling broken gold or jewellery there will meet the pennyweight regularly in buy-back offers and price lists.
Typical use cases:
- Valuing scrap gold and jewellery at buy-back
- Weight figures in US coin catalogues and auction listings
- Dental-gold valuation (particularly in the North American market)
The spot price per dwt is easy to work out:
Price/dwt = spot price (USD/ozt) ÷ 20
You can obtain current conversions and the melt value of scrap gold in dwt quickly with the Unit Converter or the Melt Value Calculator.
Distinguishing it from similar units
The pennyweight is exclusively part of the troy system and must not be confused with the avoirdupois system used for everyday goods. Smaller regional units such as the tola (South Asia, ≈ 11.66 g = 7.5 dwt) or the tael (East Asia) are also widely used, but they are not compatible with the pennyweight system.
In a nutshell
One pennyweight equals precisely 1.55517 grams, or 1/20 of a troy ounce, and remains the most common small unit in the Anglo-American jewellery and scrap-gold trade. Anyone comparing offers there should keep the simple rule "÷ 20 = troy ounces" close to hand.