All Weight Units

How to Convert Weight Units?

Weight conversion is crucial for cooking, shipping, fitness tracking, and scientific applications. This converter uses precise conversion factors to translate between metric and imperial weight units. Enter any weight value, select the source unit, and instantly see the equivalent in all other weight units including kilograms, pounds, ounces, and more.

Units

Kilogram (kg)

The kilogram is the base unit of mass in the SI system. It was originally defined as the mass of one liter of water at 4 degrees Celsius. Today, it's defined using Planck's constant. Kilograms are the standard unit for body weight, food products, and most commercial goods worldwide.

Pound (lb)

The pound is the primary unit of weight in the US customary and British imperial systems. One pound equals exactly 0.45359237 kilograms or 16 ounces. It's commonly used for body weight, food packaging, and shipping in the United States.

Ounce (oz)

The ounce is a unit of weight equal to 1/16 of a pound or approximately 28.35 grams. It's commonly used in the US for food portions, postal weights, and precious metals. Note that fluid ounces measure volume, not weight.

Gram (g)

The gram is a metric unit equal to 1/1000 of a kilogram. It's used worldwide for measuring small quantities in cooking, nutrition labels, jewelry, and scientific applications. One gram is roughly the weight of a paperclip.

Stone (st)

The stone is a British unit of weight equal to 14 pounds or approximately 6.35 kilograms. It's primarily used in the UK and Ireland for expressing body weight. For example, a person might say they weigh '10 stone 5 pounds'.

Common Weight Conversions

Frequently Asked Questions

How many pounds is 1 kilogram and how do I convert kg to lbs quickly?

One kilogram equals exactly 2.20462262 pounds, so for quick mental math multiply kilograms by 2.2 (or add 10% to that doubled value for more accuracy). Examples: 10 kg is about 22 lbs, 50 kg is 110 lbs, 70 kg is 154 lbs, 100 kg is 220 lbs. Going the other way, divide pounds by 2.2 or multiply by 0.454. The exact factor came from the international agreement of 1959 that defined the pound (avoirdupois) as exactly 0.45359237 kg. This same factor applies in the US, UK, Canada, Australia, and every other country using avoirdupois pounds. For shipping labels and medical doses where 1-2% errors matter, always use the full factor 2.20462, not the rounded 2.2.

What is the difference between weight and mass and does it matter for everyday use?

Strictly, mass is the amount of matter in an object (measured in kilograms or grams) and is the same everywhere in the universe, while weight is the gravitational force on that mass (measured in newtons) and changes with location — you weigh slightly less at the equator than at the poles, and only 1/6 as much on the Moon. In everyday English, kitchen scales, gym scales, and shipping companies all use kilograms or pounds to mean mass even though they label it weight. For cooking, shipping, and personal health this distinction does not matter because gravity on Earth is uniform enough. It matters in physics, engineering force calculations, aerospace and anywhere objects move between gravitational fields. A 70 kg person on Earth weighs about 686 N at sea level.

What is the difference between an ounce of weight and a fluid ounce?

They are completely different units that share a name. The avoirdupois ounce (oz) measures weight or mass: 1 oz = 28.3495 grams, with 16 oz in one pound. The fluid ounce (fl oz) measures volume: 1 US fl oz = 29.5735 milliliters, 1 UK (imperial) fl oz = 28.4131 ml. The US fluid ounce and UK fluid ounce differ by about 4%, which matters for recipes and cocktail measurements. To make matters more confusing, 1 fluid ounce of water happens to weigh almost exactly 1 ounce, which is the historical origin of the shared name. There is also a troy ounce used for precious metals (gold, silver, platinum): 1 troy oz = 31.1035 grams, about 10% heavier than the avoirdupois ounce.

Why does my US recipe say 1 cup of flour weighs 120 g but European recipes use grams directly?

Volume measurements like cups and tablespoons are convenient for liquids but inaccurate for dry ingredients because density varies with how packed or sifted the material is. A scooped, packed cup of flour can weigh 140 g while a lightly spooned cup weighs 115 g — that 20% variation can ruin baking. European recipes almost universally use weights in grams because a kitchen scale gives reproducible results regardless of brand, humidity, or measuring technique. The US bakery industry standardized cup-to-gram weights (1 cup all-purpose flour = 120 g, 1 cup granulated sugar = 200 g, 1 cup butter = 227 g) but home recipes still vary. For consistent baking results, weigh ingredients in grams — even US chefs have shifted toward digital scales over the past decade for this reason.

What is a metric ton and how does it differ from a US ton and UK ton?

There are three different tons in common use. The metric ton (also called tonne, symbol t) equals exactly 1,000 kg or 2,204.62 pounds, used worldwide for shipping, industry, and trade. The US ton (short ton) equals 2,000 pounds or 907.185 kg. The UK ton (long ton, also called imperial ton) equals 2,240 pounds or 1,016.05 kg. So a metric ton is about 10% heavier than a short ton and about 1.6% lighter than a long ton. Cargo manifests, freight charges, and CO2 emissions reports almost always use metric tons internationally. When reading US engineering documents, double-check whether ton means short ton or metric ton — the difference can be costly. The British have largely shifted to metric tons since the 1980s.

Why is 1 stone equal to 14 pounds and where is the stone still used?

The stone (st) is a British imperial unit equal to exactly 14 pounds or 6.35029 kg. The 14-pound value was standardized in 1389 for weighing wool, but historical stones varied from 4 to 32 pounds depending on the commodity (a stone of meat differed from a stone of cheese). Today the stone is still commonly used in the UK and Ireland to express body weight in casual conversation — someone says they weigh 11 stone 4 pounds (158 lbs / 71.7 kg). UK doctors usually record weight in kilograms but patients understand stones. The stone is not used in the United States, Canada, Australia, or New Zealand. It is also obsolete for almost all commercial and scientific purposes — only personal body weight retains the unit in modern usage.

Why is gold and silver measured in troy ounces instead of regular ounces?

Precious metals — gold, silver, platinum, palladium — and gemstones are weighed in troy ounces, where 1 troy oz = 31.1034768 grams, compared to the avoirdupois ounce of 28.3495 g. The troy ounce comes from the medieval city of Troyes, France, a major trading hub for precious goods, and was standardized in 1527 in England specifically for coinage and bullion. There are 12 troy ounces in a troy pound (not 16 as in avoirdupois), so 1 troy pound = 373.24 g, lighter than the avoirdupois pound of 453.59 g. Always confirm which ounce is meant when buying or selling precious metals — a 1 oz gold coin is one troy ounce, about 10% heavier than a standard kitchen ounce. The price of gold per ounce always refers to troy ounces.

How accurate is my bathroom scale and what is the difference between dry and wet weight?

Consumer bathroom scales typically claim 100 g (0.2 lb) precision but real-world accuracy is often 0.2-0.5 kg due to placement on uneven floors, battery condition, and calibration drift. Digital scales are more consistent than analog dial scales. For tracking weight loss, weigh at the same time of day (morning, after toilet, before eating) on the same surface to minimize variation. Dry weight versus wet weight matters in fitness and medicine: wet weight is what a scale shows (total body mass including water), dry weight refers to lean tissue mass excluding water, fat, and gut contents — useful in dialysis to track fluid balance. Body composition scales using bioelectrical impedance estimate fat percent and water percent, but their accuracy is roughly +/- 4% versus the gold-standard DEXA scan.