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Weight and Mass Converter

Convert between kilograms, grams, pounds, ounces, stones and tons. Exact factors based on the international pound of 0.45359237 kg.

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Check this before you rely on it. This converter is provided free and without warranty, and its results are not professional advice.

Popular weight conversions

kg to lbslbs to kggrams to ouncesounces to gramskg to stonesstones to lbsgrams to lbslbs to gramsmg to grams

Weight unit reference chart

What one of each unit is worth in kilograms, the base unit used for every conversion in this category.

Weight units expressed in kilograms
UnitSymbol1 unit in kg
kilogramskg1 kg
gramsg0.001 kg
poundslb0.45359237 kg
ouncesoz0.02834952313 kg
milligramsmg0.000001 kg
metric tonst1,000 kg
stonesst6.35029318 kg
US tonston907.18474 kg
microgramsµg1e-9 kg
long tonslong tn1,016.046909 kg
caratsct0.0002 kg
grainsgr0.00006479891 kg
troy ouncesoz t0.0311034768 kg
troy poundslb t0.3732417216 kg
pennyweightsdwt0.00155517384 kg
dramsdr0.001771845195 kg
slugsslug14.59390294 kg
atomic mass unitsu1.660539067e-27 kg

Weight units explained

Kilograms (kg)

The kilogram is the SI base unit of mass. Since 2019 it has been defined by fixing the Planck constant, replacing the platinum-iridium cylinder held near Paris.

Grams (g)

The gram is one thousandth of a kilogram. It is the practical unit of cooking, nutrition labels and postal weights in metric countries.

Pounds (lb)

The international avoirdupois pound is defined as exactly 0.45359237 kilograms. It is the everyday unit of body weight and grocery weight in the United States.

Ounces (oz)

The avoirdupois ounce is one sixteenth of a pound, or exactly 28.349523125 grams. Do not confuse it with the fluid ounce, which measures volume.

Milligrams (mg)

The milligram is one thousandth of a gram and is the standard unit for stating medicine dosages and micronutrient content.

Metric tons (t)

The metric ton, or tonne, is exactly 1,000 kilograms. It is the standard unit for freight, industrial output and carbon emissions.

Stones (st)

The stone equals 14 pounds, or about 6.35 kilograms. It is still the customary way to state body weight in the United Kingdom and Ireland.

US tons (ton)

The US ton, or short ton, is 2,000 pounds — about 907.18 kilograms. It is the ton used in American freight and construction.

Micrograms (µg)

The microgram, often written mcg on supplement labels, is one millionth of a gram.

Frequently asked questions

What is the base unit of weight?

This converter routes every weight conversion through the kilogram. Converting from one unit to another means converting to kilograms first and then out again, which keeps every pair consistent with every other pair.

How accurate are these weight conversions?

Results are shown to 10 significant digits using exact defined factors wherever a unit has one. No rounding is applied beyond that final display step.

All weight conversions

Every weight conversion page on this site, 146 in total.