What is pound?
A pound is a unit of mass in imperial and US customary systems equal to 16 ounces. It is widely used in the United States for body weight, grocery shopping, and general weight measurement.
Real-world uses
Pounds are the primary unit of weight in everyday American life—used for body weight, grocery items, luggage limits, and newborn birth weights. In the UK, pounds remain common for body weight despite official metrication.
History
The pound descends from the Roman "libra pondo" (a pound by weight), which is why its abbreviation is "lb." The avoirdupois pound was standardized internationally in 1959 as exactly 0.45359237 kilograms.
Common mistakes
Confusing pounds-mass (lb) with pounds-force (lbf), which are technically different quantities. Also, assuming the pound symbol "£" relates to weight—it actually denotes British currency, though both derive from "libra."
What is ounce?
An ounce is a unit of mass in imperial and US customary systems equal to approximately 28.35 grams. It is frequently used in cooking, food portioning, and the measurement of precious metals.
Real-world uses
Ounces are used in the US and UK for food packaging, postal weights, and cooking recipes. Precious metals are weighed in troy ounces (slightly heavier than avoirdupois ounces) on commodity exchanges worldwide.
History
The word "ounce" comes from the Latin "uncia," meaning one-twelfth (of a Roman pound). The avoirdupois ounce became standard in English trade by the 14th century, defined as 1/16 of an avoirdupois pound.
Common mistakes
Confusing avoirdupois ounces (28.35 g, used for general weight) with troy ounces (31.10 g, used for precious metals) or fluid ounces (a volume measure). These are three distinct units sharing the name "ounce."
When is this conversion used?
Body weight, grocery items, and luggage limits are commonly expressed in kilograms in most countries and pounds in the US and UK, making this one of the most frequently needed mass conversions. Cooking recipes and food packaging often switch between grams and ounces, especially when adapting recipes from different culinary traditions.
Worked examples
1 pound = 16 ounce
1 ounce = 0.02834952 kilogram
How to convert pound to ounce
To convert pound to ounce, multiply the value by 16.
To convert ounce back to pound, multiply by 0.0625.
Measurement standards
The kilogram is defined by fixing the Planck constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds, as established at the 26th General Conference on Weights and Measures in 2018. This ended the last SI definition based on a physical artefact.
Did you know?
The International Prototype of the Kilogram, a platinum-iridium cylinder stored near Paris since 1889, was found to have drifted by about 50 micrograms relative to its copies over a century — roughly the mass of a fingerprint.
Quick reference: pound to ounce
| pound | ounce |
|---|---|
| 0.1 | 1.6 |
| 0.5 | 8 |
| 1 | 16 |
| 2 | 32 |
| 5 | 80 |
| 10 | 160 |
| 25 | 400 |
| 50 | 800 |
| 100 | 1,600 |
| 250 | 4,000 |
| 500 | 8,000 |
| 1,000 | 16,000 |
Common values
| pound | ounce | |
|---|---|---|
| A paperclip | 2.20462262 pound | 35.27396195 ounce |
| A smartphone | 385.80895882 pound | 6,172.94334118 ounce |
| A bag of sugar | 2.20462262 pound | 35.27396195 ounce |
| Average adult human | 154.32358353 pound | 2,469.17733647 ounce |
| A small car | 2,645.54714622 pound | 42,328.7543395 ounce |