How many kilograms is 1 ounce?

One ounce (avoirdupois) equals exactly 0.0283495231 kilograms, or approximately 28.35 grams. This is the standard international conversion factor defined under the International Yard and Pound Agreement of 1959. To convert any weight in ounces to kilograms, multiply the number of ounces by 0.0283495231.

How do I convert ounces to kilograms?

To convert ounces to kilograms, multiply the number of ounces by 0.0283495231. For example, 16 oz x 0.0283495231 = 0.4536 kg (one pound). A quick mental approximation is to divide the ounces by 35.274, which is the number of ounces in one kilogram.

What is the difference between a troy ounce and an avoirdupois ounce?

The avoirdupois ounce (used for everyday weights, food, and body weight) equals 28.3495 grams. The troy ounce (used for precious metals like gold and silver) equals 31.1035 grams. This converter uses the avoirdupois ounce. If you are converting gold or silver weights, use a troy ounce converter, as 1 troy oz = 0.0311035 kg, not 0.0283495 kg.

Ounce to Kg Converter

This converter turns a weight in ounces (oz) into kilograms (kg) using the exact avoirdupois conversion factor of 1 oz = 0.0283495231 kg, the standard set by the International Yard and Pound Agreement of 1959. Enter any weight in ounces, a figure of 16 oz is loaded by default, and choose how many decimal places you want in the answer, from 2 up to 6. The calculator instantly returns three results, your original weight in ounces, the equivalent in kilograms, and the same weight in grams, so you can check whichever unit you need without doing the maths by hand. Below the results sits a ready-made table showing common weights from 1 oz to 1,000 oz alongside their kilogram, gram and pound equivalents, handy for postage, cooking, luggage or freight weights. This tool uses the everyday avoirdupois ounce, the one used for food packaging, body weight and postal items, not the troy ounce used to weigh gold, silver and other precious metals, which is roughly 10 percent heavier. If you are converting a bullion or jewellery weight, you will need a troy ounce converter instead, or your result will read slightly under the true figure. With the default 16 oz entered, the calculator confirms the result is exactly one pound, 0.4536 kg, since 16 ounces make up a pound in the imperial system.

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Standard conversion International avoirdupois ounce. Defined by the International Yard and Pound Agreement 1959.

Weight in Ounces

Ounces (oz) to convert

Decimal places in result

Quick Reference

Conversion factor:

1 oz = 0.0283495231 kg

Inverse factor:

1 kg = 35.2739619 oz

This converter uses the avoirdupois ounce, the standard unit for everyday goods. For gold and silver use a troy ounce converter (1 troy oz = 0.0311035 kg).

Conversion Result

Ounces

oz (avoirdupois)

Kilograms
0.4536
kg

Grams

453.59

Common Ounce to Kilogram Conversions

Ounces (oz)	Kilograms (kg)	Grams (g)	Pounds (lb)

How to Convert Ounces to Kilograms

To convert ounces to kilograms, multiply the number of ounces by 0.0283495231. This factor comes from the exact definition of the international avoirdupois ounce, which equals exactly 28.349523125 grams, or 0.028349523125 kilograms.

The formula is:

kg = oz x 0.0283495231

For example, to convert 16 ounces to kilograms: 16 x 0.0283495231 = 0.4536 kg. This result is also exactly one avoirdupois pound (0.45359237 kg), because there are 16 ounces in one pound.

Worked Example

Convert 16 oz to kg:

Start with 16 oz
Multiply by the conversion factor: 16 x 0.0283495231
Result: 0.4536 kg (to 4 decimal places)
In grams: 16 x 28.3495231 = 453.59 g (to 2 decimal places)

This matches the calculator's default output with 16 oz entered.

Avoirdupois vs Troy Ounces

There are two common types of ounce in use today:

Avoirdupois ounce: 28.3495 g (0.028350 kg). Used for food, body weight, postal packages, and everyday goods in countries that use imperial measurements.
Troy ounce: 31.1035 g (0.031104 kg). Used exclusively for precious metals such as gold, silver, and platinum. A troy ounce is about 10% heavier than an avoirdupois ounce.

This converter uses the avoirdupois ounce. If you are converting a weight from a precious metals listing, use a troy ounce converter instead.

Quick Conversion Reference

Ounces (oz)	Kilograms (kg)	Common context
1 oz	0.0283 kg	A standard letter or small item
8 oz	0.2268 kg	Half a pound
16 oz	0.4536 kg	One pound (1 lb)
32 oz	0.9072 kg	Two pounds
35.274 oz	1.0000 kg	Exactly one kilogram
100 oz	2.8350 kg	A large package
160 oz	4.5359 kg	Ten pounds

Related Converters

Essential Calculators: all unit converters and tools.
Kg to Ounce Converter: convert kilograms back to ounces.
Grams to Ounces Calculator: convert grams to oz.
Grams to Pounds Converter: convert grams to pounds.
Pounds to Grams Converter: convert pounds to grams.
Metric to Imperial Converter: a full metric-to-imperial weight and length tool.

Sources and method: International Yard and Pound Agreement (1959), which defined the avoirdupois pound as exactly 0.45359237 kg, making the ounce (1/16 lb) exactly 0.028349523125 kg. National Institute of Standards and Technology (NIST) Special Publication 811.

This converter uses the avoirdupois ounce. Troy ounces (used for precious metals) are approximately 10% heavier at 31.1035 g each. For everyday goods, food packaging, and postal weights, the avoirdupois ounce applies.