Pounds to Pennyweights (lb to dwt)

1 pound equals 291.6666667 pennyweights (rounded).

1 pound = 291.6666667 pennyweights

How to convert pounds to pennyweights

To convert pounds to pennyweights, multiply the number of pounds by 291.6666667. The factor is rounded to 10 significant digits. To go the other way, multiply pennyweights by 0.003428571429 (rounded).

pennyweights = pounds × 291.6666667

Example: 10 pounds = 2,916.666667 pennyweights.

About these units

Pound (lb)

US & ImperialCurrent unit

Exactly 0.45359237 kg, divided into 16 ounces. The standard unit of weight in the US and common in the UK.

Why is pound abbreviated lb? The answer is Roman. The English word comes from the Latin libra pondo, roughly the weight measured in libra, and the symbol keeps the first word. The Roman libra was divided into 12 unciae. The avoirdupois pound of 16 ounces came into general use around 1300 and was initially equal to 6,992 troy grains; under Elizabeth I it was redefined as 7,000 grains. The UK's Weights and Measures Act 1878 set the imperial standard pound as a platinum cylinder, and the troy pound was abolished for trade the following year.

Today the pound is defined from the kilogram. The International Yard and Pound Agreement of 1959 fixed it at exactly 0.45359237 kg, and the UK's Weights and Measures Act 1963 wrote the same figure into law. Pounds remain the everyday unit for body weight, groceries and shipping in the United States and are widely used in the UK. The word also survives in odd places: a six-pounder cannon was named for the weight of its shot, not its own.

1 pound = 0.45359237 kilograms (exactly).

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

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

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