Libras (Castilian) to Grams (libra to g)

1 libra (Castilian) equals 460.093 grams exactly.

1 libra (Castilian) = 460.093 grams

How to convert libras (Castilian) to grams

To convert libras (Castilian) to grams, multiply the number of libras (Castilian) by 460.093. This factor is exact. To go the other way, multiply grams by 0.002173473624 (rounded).

grams = libras (Castilian) × 460.093

Example: 10 libras (Castilian) = 4,600.93 grams.

Approximate value. Standards for the libra (Castilian) varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.

About these units

Libra (Castilian) (libra)

Spanish & PortugueseHistorical unit (no longer in standard use)Approximate value

About 460.09 g, the Castilian pound. The Spanish libra and arroba were used throughout Spain and its colonies.

Latin libra, a pound, gave Castilian Spanish its basic weight, subdivided into 16 onzas of about 28 g each. Castile kept the unit through the Middle Ages, and the national standard enacted in 1801 fixed it at exactly 0.460093 kg, the figure used here. That is about 460 g, a little more than a half-ounce above the avoirdupois pound.

Before and after that decree, local libras differed a great deal. Huesca used one near 0.351 kg, Pontevedra one near 0.579 kg, and apothecaries in Barcelona used a medicinal libra of only 0.300 kg. Standardization on paper did not remove these customs quickly, so merchants had to know which city's pound a price referred to.

Larger Castilian weights were built from the libra. The arroba was 25 libras, about 11.5 kg, and the quintal 100 libras, about 46 kg. These were used for wool, olive oil, tobacco, silver and other goods across Spain and its American colonies until metric weights replaced them in the nineteenth century, though the libra survives informally as the pound in Latin America.

1 libra (Castilian) = 0.460093 kilograms (approximately).

Sources: Wikipedia: Spanish customary units; Wikipedia: Arroba

Gram (g)

Metric (SI)Current unit

One thousandth of a kilogram. The standard unit for food quantities and small objects.

A gram was once defined as a small drop of the natural world. The French National Convention of 1795 set it as the absolute weight of a volume of pure water equal to a cube one hundredth of a metre on each side, a cubic centimetre. The reference temperature was first the melting point of ice and was later changed to the temperature of maximum density of water, about 4 degrees Celsius. The word came into French as gramme, from Late Latin gramma, itself from the Greek for a letter or small mark; in Late Antiquity it meant about one twenty-fourth of an ounce.

The gram was the base unit of mass in the centimetre-gram-second system, but in 1960 the SI took the kilogram as its base unit, which made the gram one thousandth of it. That is why it appears in so many everyday places: it is the standard for non-liquid ingredients in cooking and shopping, and nutrition labels commonly list contents per 100 g. For a sense of scale, a small paper clip or a pen cap weighs about a gram, and a Japanese 1-yen coin is close to exactly that, while a US penny is around 2.5 g.

1 gram = 0.001 kilograms (exactly).

Sources: Wikipedia: Gram; Wikipedia: Kilogram

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