Weight Converter

Free Online Weight Converter

This weight converter instantly converts between metric and imperial/US units of mass, including milligrams (mg), grams (g), kilograms (kg), metric tons (t), carats (ct), ounces (oz), pounds (lb), stones (st), US tons (short tons), and UK tons (long tons). It works as a kg to pounds converter, grams to ounces converter, pounds to kg calculator, stone to kg converter, and ton to kg converter all in one tool, so you never need to remember individual conversion formulas or search for a separate calculator for each unit pair.

Whether you're a student solving unit conversion problems in science class, a fitness enthusiast tracking body weight across kg and lb, a chef or baker scaling recipes between grams and ounces, an online shopper comparing product weight listed in different units, or a logistics professional calculating shipping weight in tons, this weight conversion calculator gives you an instant, accurate result along with a visual diagram and complete step-by-step working.

How to Use This Weight Conversion Calculator

Using this online weight converter takes only three quick steps. Enter the numeric value you want to convert, choose the unit you're converting from in the "From" dropdown, and choose the unit you want to convert to in the "To" dropdown — the converted result updates instantly as you type. Use the swap button to instantly reverse the conversion direction, or tap one of the popular conversion shortcuts like kg to lb, g to oz, or stone to kg.

• Type the weight value you want to convert
• Select the unit you're converting from (metric or imperial/US)
• Select the unit you want to convert to
• Read the converted weight, the unit rate, and the visual conversion diagram

Weight Conversion Formula

Every weight conversion uses the kilogram as a common base unit, since the kilogram is the SI (International System of Units) standard for mass. To convert any value from one unit to another, the calculator first multiplies the input by that unit's kilogram factor to get the weight in kilograms, then divides by the target unit's kilogram factor to reach the final answer.

• Step 1: Value in kilograms = Input value × (kilogram factor of the "From" unit)
• Step 2: Result = Value in kilograms ÷ (kilogram factor of the "To" unit)
• Combined formula: Result = Input value × (From unit's kg factor ÷ To unit's kg factor)
• Example shortcut: to convert kilograms directly to pounds, multiply by 2.20462 (since 1 lb = 0.45359237 kg)

Common Weight Conversion Factors

These are the exact kilogram-based conversion factors this calculator uses internally. Knowing them is useful for quick mental estimates even when you don't have the calculator open:

• 1 milligram (mg) = 0.000001 kilograms
• 1 gram (g) = 0.001 kilograms
• 1 kilogram (kg) = 1 kilogram (the base unit)
• 1 metric ton (t) = 1,000 kilograms
• 1 carat (ct) = 0.0002 kilograms = 0.2 grams
• 1 ounce (oz) = 0.028349523125 kilograms
• 1 pound (lb) = 0.45359237 kilograms = 16 ounces
• 1 stone (st) = 6.35029318 kilograms = 14 pounds
• 1 US ton (short ton) = 907.18474 kilograms = 2,000 pounds
• 1 UK ton (long ton) = 1,016.0469088 kilograms = 2,240 pounds

Worked Example: Kilograms to Pounds

Suppose you want to convert a 70 kg body weight into pounds. First, look up the conversion factor: 1 kilogram equals 2.20462 pounds (or equivalently, 1 pound equals 0.45359237 kg). Multiplying, 70 kg × 2.20462 = 154.32 pounds. So a 70 kg person weighs about 154.3 lb — exactly what the diagram above shows when you enter 70 in the "From: Kilogram" field and select "To: Pound".

Now try the reverse direction: converting 16 ounces of flour into grams. Since 1 ounce equals 28.349523125 grams, you multiply directly: 16 oz × 28.349523125 = 453.59 grams. This two-step "convert to the base unit, then convert out" method is exactly what powers every conversion this calculator performs, no matter which two weight units you choose.

Metric vs Imperial/US Weight Units

The metric system (milligrams, grams, kilograms, metric tons) is used by nearly every country in the world and is based on powers of 10, which makes conversions within the system simple — just move the decimal point. The imperial and US customary system (ounces, pounds, stones, US tons, UK tons) is still widely used for body weight, food packaging, and everyday measurement in the United States and, for some purposes like body weight, in the United Kingdom.

Because these two systems don't share a simple round-number relationship, converting between them — such as kilograms to pounds, grams to ounces, or stones to kilograms — normally requires a calculator or a memorized conversion factor. This tool removes that friction entirely by handling metric-to-imperial/US and imperial/US-to-metric weight conversions with the same accuracy in both directions.

Where Weight Conversion Is Used

Weight conversion comes up constantly outside the classroom, in situations where mass measurements from two different systems need to be compared or combined:

• Health and fitness, tracking body weight, protein intake, or gym plates between kg and lb
• Cooking and baking, converting recipe ingredient weights between grams and ounces
• E-commerce and shipping, calculating parcel or freight weight across metric and imperial systems
• Jewelry and gemstones, converting gem weight between carats and grams
• Manufacturing and engineering, standardizing material weight to kilograms or metric tons for calculations
• Agriculture and trade, converting bulk commodity weight between tons, kilograms, and pounds