Weight Converter
Free Online Weight Converter
A weight converter changes a measurement of mass from one unit into another while keeping the actual amount the same. With this tool you can turn kilograms into pounds, grams into ounces, tonnes into stones, and many other combinations in a single step. It supports both metric units, which most of the world uses, and imperial units, which remain common in the United States and the United Kingdom.
The need to convert weight shows up far more often than people expect. A cook following a recipe from another country, a traveler checking a luggage limit, a shopper comparing product sizes, and a shipper calculating freight all run into mass units that differ from the ones they grew up with. This converter removes the guesswork and gives an accurate answer right away, along with the formula used to reach it.
Mass Versus Weight
In everyday speech, weight and mass are used as if they mean the same thing, and for most practical purposes that is fine. Strictly speaking, though, they are different. Mass is the amount of matter in an object and does not change no matter where the object is. Weight is the force that gravity exerts on that mass, which is why an astronaut weighs less on the Moon even though their mass stays the same.
The units handled by this converter, such as kilograms, grams, and pounds, are technically units of mass, even though we call the activity weighing. On the surface of the Earth, gravity is steady enough that treating mass and weight as interchangeable causes no trouble in cooking, shipping, or shopping. This tool follows that common usage so it matches how people actually talk about weight every day.
How the Weight Converter Works
The converter uses a single base unit, the gram, as a common reference. Every supported unit is defined by how many grams it represents. A kilogram is 1,000 grams, a pound is about 453.592 grams, and an ounce is about 28.35 grams. By passing every value through grams, the tool can convert accurately between any two units without losing precision.
The calculation runs in two stages. First, your value is multiplied by the factor of the unit you are converting from, which expresses it in grams. Second, that gram value is divided by the factor of the unit you want, producing the final result. The converter displays this exact formula so the answer is transparent and easy to verify.
The Conversion Formula
The general rule is result = (value × fromFactor) ÷ toFactor, where each factor is the number of grams in that unit. Imagine converting 2 kilograms to pounds. The kilogram factor is 1,000 grams and the pound factor is 453.592 grams. The math is (2 × 1,000) ÷ 453.592, which equals about 4.41 pounds. The same approach works for every unit in the list.
Metric Units of Weight
The metric system organizes mass around the gram and scales it with decimal prefixes, so units relate to each other by powers of ten. This makes the system easy to use in science, medicine, and most of the world.
- Tonne (metric ton): Equal to 1,000 kilograms, used for heavy cargo, vehicles, and industrial quantities.
- Kilogram (kg): The everyday base unit, used for body weight, groceries, and most shipping.
- Gram (g): One thousandth of a kilogram, used for food portions, ingredients, and small items.
- Milligram (mg): One thousandth of a gram, used for medicine doses and very small amounts.
Imperial and US Customary Units
Imperial weight units do not follow a neat decimal pattern, which is exactly why a converter saves time. They remain standard in the United States and appear in the United Kingdom for body weight and some everyday uses.
- Ounce (oz): The smallest common imperial unit, used for food, mail, and small goods. There are 16 ounces in a pound.
- Pound (lb): Equal to 16 ounces or about 453.6 grams, used widely for body weight and groceries in the US.
- Stone (st): Equal to 14 pounds, used in the UK and Ireland mainly for body weight.
- US ton: Equal to 2,000 pounds, used in the United States for heavy loads, distinct from the metric tonne.
Common Weight Conversions at a Glance
| From | To | Result |
|---|---|---|
| 1 kilogram | pounds | 2.205 lb |
| 1 pound | kilograms | 0.454 kg |
| 1 ounce | grams | 28.35 g |
| 1 gram | ounces | 0.035 oz |
| 1 stone | kilograms | 6.350 kg |
| 1 tonne | pounds | 2,204.6 lb |
| 1 pound | ounces | 16 oz |
How to Convert Weight by Hand
Knowing the manual method helps you double check results and make quick estimates. To convert kilograms to pounds, multiply by 2.205. To go from pounds to kilograms, multiply by 0.454, or divide by 2.205. For grams to ounces, divide by 28.35, and for ounces to grams, multiply by 28.35.
A handy mental shortcut is that a kilogram is a little over two pounds, so a 70 kilogram person weighs about 154 pounds. Going the other way, a 10 pound bag is roughly 4.5 kilograms. These estimates are useful in a pinch, while the converter delivers the precise figure when accuracy counts.
Where Weight Conversion Matters
Cooking and Baking
Recipes travel across borders, and so do their measurements. A European baking recipe lists ingredients in grams, while an American one uses ounces and pounds. Baking in particular rewards precision, since the ratio of flour to liquid affects the result. Converting weights correctly keeps a recipe true to its original and helps your results turn out as intended.
Travel and Shipping
Airlines set luggage limits in kilograms or pounds depending on the carrier and route, so a traveler often needs to convert to avoid extra fees. Shipping companies price packages by weight, and online sellers list product weights in whichever system is local. Converting these figures helps you plan, budget, and pack without surprises at the counter.
Health and Fitness
Body weight is reported in kilograms in many countries, in pounds in the US, and in stones and pounds in the UK. People tracking weight goals, comparing fitness data, or following programs from another region need to convert between these to stay consistent. Medication doses also depend on body weight, where accurate conversion is genuinely important.
Science and Industry
Laboratories and manufacturers work mostly in metric units, but they often deal with equipment, materials, or partners that use imperial measures. Converting between grams, kilograms, and pounds keeps production, quality control, and research consistent across teams and suppliers that may not share the same system.
The Metric and Imperial Divide
Most countries adopted the metric system for its simple decimal structure, while the United States kept customary units for daily life. The United Kingdom uses a mix, with metric for most trade but imperial for body weight and some traditions. This blend means international cooking, commerce, and travel regularly call for weight conversion, and a reliable tool prevents the small errors that can add up.
Tips for Accurate Weight Conversion
- Check whether a ton is metric or US. A metric tonne is 1,000 kilograms, while a US ton is 2,000 pounds, which is roughly 907 kilograms. They are not the same.
- Mind the difference between mass units and fluid measures. A fluid ounce measures volume, not weight, so do not confuse it with the weight ounce.
- Keep extra decimal places for recipes. Small rounding errors matter in baking, so carry more digits and round at the end.
- Use estimates to catch mistakes. If a kilogram converts to dozens of pounds, you likely chose the wrong units.
Frequently Asked Questions
How many pounds are in a kilogram?
One kilogram equals about 2.205 pounds. To convert any number of kilograms to pounds, multiply by 2.205. So 5 kilograms is about 11.02 pounds.
How do I convert grams to ounces?
Divide the number of grams by 28.35, since one ounce equals about 28.35 grams. For example, 100 grams is about 3.53 ounces.
What is the difference between a metric tonne and a US ton?
A metric tonne equals 1,000 kilograms, about 2,204.6 pounds. A US ton equals 2,000 pounds, about 907 kilograms. Always confirm which one a figure refers to.
Is a fluid ounce the same as a weight ounce?
No. A fluid ounce measures volume, while a weight ounce measures mass. They share a name but are different quantities, so use a volume converter for fluid ounces.
How many pounds are in a stone?
One stone equals 14 pounds, which is about 6.35 kilograms. The stone is used mainly in the UK and Ireland for body weight.
Why Use This Weight Converter
This converter is free, needs no registration, and works on any device. It updates results instantly as you type, shows the formula behind each conversion, and covers metric and imperial units together in one place. Whether you are cooking, packing for a trip, tracking fitness, or working in a lab, it gives you an accurate answer every time. Save the page so a dependable weight conversion is always within reach.