ounce (oz)
1 ounce = 0.02834952 kilograms
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.
Notes: Imperial/USCS unit
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?
Converting between ounce and kilogram is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. 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.
How to convert ounce to kilogram
To convert ounce to kilogram, multiply the value by 0.02834952.
Conversion formula (from base unit)
x * 0.028349523125
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.
| ounces | kilograms |
|---|---|
| 0.1 | 0.00283495 |
| 0.5 | 0.01417476 |
| 1 | 0.02834952 |
| 2 | 0.05669905 |
| 5 | 0.14174762 |
| 10 | 0.28349523 |
| 25 | 0.70873808 |
| 50 | 1.41747616 |
| 100 | 2.83495231 |
| 250 | 7.08738078 |
| 500 | 14.17476156 |
| 1,000 | 28.34952313 |
Common values
| ounces | kilograms | |
|---|---|---|
| A paperclip | 0.03527396 ounces | 0.001 kilograms |
| A smartphone | 6.17294334 ounces | 0.175 kilograms |
| A bag of sugar | 35.27396195 ounces | 1 kilogram |
| Average adult human | 2,469.17733647 ounces | 70 kilograms |
| A small car | 42,328.7543395 ounces | 1,200 kilograms |
Full ounce conversion table
| Unit | Value | Factor |
|---|---|---|
| kilogram | 1 oz = 0.02834952 kg | × 0.02834952 |
| gram | 1 oz = 28.34952313 g | × 28.34952313 |
| pound | 1 oz = 0.0625 lb | × 0.0625 |
| tonne | 1 oz = 0.00002835 t | × 0.00002835 |
| milligram | 1 oz = 28,349.523125 mg | × 28,349.523125 |
| microgram | 1 oz = 28,349,523.125 µg | × 28,349,523.125 |
| stone | 1 oz = 0.00446429 st | × 0.00446429 |
| short ton (US) | 1 oz = 0.00003125 short ton | × 0.00003125 |
| long ton (UK) | 1 oz = 0.0000279 long ton | × 0.0000279 |