Pennyweights to Ounces (dwt to oz)

1 pennyweight equals 0.05485714286 ounces (rounded).

1 pennyweight = 0.05485714286 ounces

How to convert pennyweights to ounces

To convert pennyweights to ounces, multiply the number of pennyweights by 0.05485714286. The factor is rounded to 10 significant digits. To go the other way, multiply ounces by 18.22916667 (rounded).

ounces = pennyweights × 0.05485714286

Example: 10 pennyweights = 0.5485714286 ounces.

About these units

Pennyweight (dwt)

Troy & apothecaries'Traditional unit (still used in some regions)

One twentieth of a troy ounce (1.5552 g), originally the weight of a silver penny. Still used by jewelers.

Silver pennies gave this unit its name. In the Middle Ages an English penny weighed one twentieth of an ounce and one 240th of a pound of sterling silver, so its weight and its face value agreed. The abbreviation dwt keeps the d from denarius, the Roman coin that stood behind the old British penny.

The size changed over time. Under the medieval Tower pound a pennyweight was 32 Tower grains. When troy weights replaced Tower weights in 1527, it became 24 troy grains, which is exactly 1.55517384 grams.

Twenty pennyweights make a troy ounce, and 240 make a troy pound. Jewellers still use it to work out the precious metal content of jewellery, and dental labs have used it for gold in crowns and inlays. In parts of England, gooseberry growers also record prize fruit in pennyweights and grains.

1 pennyweight = 0.00155517384 kilograms (exactly).

Sources: Wikipedia: Pennyweight; Wikipedia: Troy weight; NIST SP 811, Appendix B.8

Ounce (oz)

US & ImperialCurrent unit

One sixteenth of a pound, exactly 28.349523125 g. Used for food, mail and consumer goods in the US and UK.

A twelfth part is what ounce originally meant. It comes from the Roman uncia, one twelfth of the Roman pound, a word that also gave English the inch. The abbreviation oz does not come from English at all but from the Italian onza or oncia. Over the centuries many regions and trades used different ounces: the English Tower ounce of 29.16 g was abolished by Henry VIII in 1527, and the Dutch ons was redefined as exactly 100 g in 1820.

The avoirdupois ounce used for everyday goods is one sixteenth of a pound, exactly 28.349523125 g or 437.5 grains, the standard in the US and under the UK imperial system. It is not the same as the troy ounce for precious metals, and neither is the fluid ounce, which measures volume. Ounces still describe portions such as steaks and burgers, and they show up in unexpected places: fabric is graded by weight per area, so a 16 oz denim is a heavy cloth, and the copper on a circuit board is specified in ounces, where 1 oz is roughly 34.7 micrometres thick.

1 ounce = 0.02834952313 kilograms (approximately).

Sources: Wikipedia: Ounce; NIST Guide to the SI, Appendix B.8 (mass conversions)

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