How many kilograms are in a pound?

Exactly 0.45359237 kg. The avoirdupois pound has this exact international definition, so an avoirdupois ounce (one-sixteenth of a pound) is 0.028349523125 kg.

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

An avoirdupois ounce is 28.3495 grams and is used for everyday weight. A troy ounce, used for precious metals, is 31.1035 grams, so it is about 10 percent heavier. Mixing them up misprices gold and silver.

One stone is 14 avoirdupois pounds, which is 6.35029318 kg. It is still common in the UK and Ireland for body weight. The tool converts it to and from every other unit automatically.

Is a tonne the same as a ton?

No. A metric tonne is exactly 1000 kg. A US short ton is 2000 pounds (about 907.18 kg) and a UK long ton is 2240 pounds (about 1016.05 kg), so all three differ. The table lists each separately.

How does the converter stay accurate?

Each unit stores an exact kilograms-per-unit factor. Your value is converted to kilograms and then divided into the target unit, so every conversion shares one base and avoids accumulated rounding error.

Mass Unit Conversion Reference

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Mass units split into several incompatible families — metric SI, everyday avoirdupois, the troy system for precious metals, and various tons — which makes a reliable converter genuinely useful. Enter a value in any unit and this reference shows it in every other, using exact factors.

How it works

Each unit stores an exact number of kilograms per unit, so the kilogram is the shared base. Conversion is two steps:

kilograms = value × kgPerUnit[from]
result    = kilograms ÷ kgPerUnit[to]

The avoirdupois pound is exactly 0.45359237 kg, and the ounce is one-sixteenth of that. The troy system is separate: a troy ounce is 0.0311034768 kg, heavier than an avoirdupois ounce, which is why precious-metal quotes use it. The three “tons” are distinct: metric tonne 1000 kg, US short ton 907.18474 kg, and UK long ton 1016.0469088 kg.

Tips and example

To convert 70 kg to pounds: 70 ÷ 0.45359237 ≈ 154.32 lb.
For gold and silver, always use the troy ounce (≈ 31.10 g), not the kitchen ounce (≈ 28.35 g) — the difference is roughly 10 percent.
A carat (for gemstones) is exactly 0.2 g, so a 5-carat stone weighs 1 g.

Very large or very small results display in scientific notation so the figures stay readable.