Weight & Mass Converter

Convert kilograms to pounds, grams to ounces, stones to kg, metric tons to tons, and more instantly. Accurate weight conversion tool for everyday and professional use.

Weight Conversion Tool

Enter any weight value and convert between metric, imperial, and other weight measurement systems instantly. Supports precise conversions for cooking, science, fitness, and daily use.

Convert Weight Instantly

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Weight Comparison
Metric Weight: 0 kg
Imperial Weight: 0 lb
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Supported Weight Units

Our converter supports a comprehensive range of weight and mass units across different measurement systems:

Metric System

International standard used worldwide (except USA):

Kilogram (kg) Gram (g) Milligram (mg) Metric Ton (t) Carat (ct)

Base Unit: 1 kilogram = 1000 grams

Imperial System

Used primarily in the United States:

Pound (lb) Ounce (oz) Stone (st) Ton (ton) Grain (gr)

Conversion: 1 pound = 16 ounces

Common Conversions

Most frequently used weight conversions:

kg ↔ lb g ↔ oz st ↔ kg mg ↔ gr t ↔ ton

Note: 1 kilogram ≈ 2.20462 pounds

Scientific Units

Used in scientific and technical contexts:

Newton (N) Atomic Mass (u) Slug (slug) Planck Mass

Note: Newton measures force, not mass

Key Conversion: 1 kilogram (kg) = 2.20462 pounds (lb) = 35.274 ounces (oz) = 0.157473 stone (st)

Common Weight Conversions

Here are the most frequently used weight conversions for quick reference:

From To Conversion Factor Example Common Use
Kilograms (kg) Pounds (lb) × 2.20462 5 kg = 11.0231 lb Body weight, gym weights
Pounds (lb) Kilograms (kg) × 0.453592 10 lb = 4.53592 kg Grocery items, luggage
Grams (g) Ounces (oz) × 0.035274 500 g = 17.637 oz Cooking, baking
Ounces (oz) Grams (g) × 28.3495 16 oz = 453.592 g Food packaging, recipes
Stones (st) Kilograms (kg) × 6.35029 12 st = 76.2035 kg Body weight (UK)
Metric Tons (t) Tons (ton) × 1.10231 2 t = 2.20462 ton Shipping, industry
Milligrams (mg) Grains (gr) × 0.0154324 1000 mg = 15.4324 gr Medicine, jewelry
Pro Tip: To quickly convert kilograms to pounds in your head, multiply by 2 and add 10%. Example: 10 kg ≈ 10 × 2 = 20, + 2 = 22 lb (actual: 22.0462 lb).

How to Use the Weight Converter

Follow these simple steps to convert any weight measurement:

Step 1: Enter Value

Enter the weight value you want to convert in the "From Value" field.

Example: 5, 10.5, 0.25

Step 2: Select From Unit

Choose the unit of your input value from the "From Unit" dropdown.

Example: kilograms, pounds, ounces

Step 3: Select To Unit

Choose the unit you want to convert to from the "To Unit" dropdown.

Example: pounds, grams, stone

Step 4: Convert

Click "Convert Weight" or use quick buttons for instant conversion.

Results appear instantly with formula

Weight Conversions in Daily Life

Weight conversions are essential in various everyday situations. Here are common scenarios where you might need to convert weights:

Cooking & Baking

Convert grams to ounces for international recipes. 250g flour = 8.82oz. Precise measurements ensure perfect results every time.

Common: g ↔ oz
Fitness & Health

Convert pounds to kilograms for weight tracking. 180lb = 81.65kg. Monitor progress and set realistic fitness goals.

Common: lb ↔ kg
Travel & Luggage

Convert kilograms to pounds for airline baggage limits. 23kg = 50.71lb. Avoid excess baggage fees when flying internationally.

Common: kg ↔ lb
Medicine & Pharmacy

Convert milligrams to grains for medication dosages. 500mg aspirin = 7.72gr. Essential for accurate prescription filling.

Precision: mg ↔ gr
Jewelry & Precious Metals

Convert carats to grams for gemstones and gold. 1 carat = 0.2g. Critical for valuation and international trade.

Specialized: ct ↔ g
Shipping & Logistics

Convert metric tons to tons for cargo weights. 5t = 5.51 tons. Essential for international shipping and freight calculations.

Industrial: t ↔ ton

Weight Measurement Systems Explained

Metric System (International)

The metric system is a decimal-based system of measurement used by most countries worldwide.

  • Base Unit: Kilogram (kg)
  • Common Units: Gram (g), Milligram (mg), Metric Ton (t)
  • Conversions: 1 kg = 1000 g = 1,000,000 mg
  • Advantages: Decimal-based, easy calculations, international standard
  • Usage: Science, medicine, most industries globally

Fun Fact: The kilogram is the only SI base unit still defined by a physical object.

Imperial System (US Customary)

The imperial system is used primarily in the United States and is based on historical British units.

  • Base Unit: Pound (lb)
  • Common Units: Ounce (oz), Stone (st), Ton (ton)
  • Conversions: 1 lb = 16 oz, 1 stone = 14 lb
  • Origin: Roman "libra pondo" (pound weight)
  • Usage: Everyday use in USA, some specialized fields

Note: The US ton (2000 lb) differs from the British ton (2240 lb).

Important Distinction: Weight and mass are different scientific concepts. Mass is the amount of matter (constant), while weight is the force of gravity on that mass (varies by location). In everyday use, they're often used interchangeably.

Historical Weight Units

Before standardization, many cultures used unique weight measurements. Some historical units are still used in specific contexts today.

Historical Unit Origin Modern Equivalent Still Used In
Stone (st) Medieval England 6.35029 kg Body weight in UK & Ireland
Carat (ct) Ancient Mediterranean 0.2 grams Gemstones, pearls, gold
Troy Ounce (oz t) Roman Empire 31.1035 grams Precious metals, bullion
Grain (gr) Ancient Egypt 64.7989 milligrams Medicine, archery, gunpowder
Quintal (q) Ancient Rome 100 kg (metric) or 100 lb (US) Agriculture in some countries
Momme (mm) Japan 3.75 grams Pearls, textiles in Japan
Did You Know? The word "pound" comes from the Latin "libra pondo" meaning "a pound weight." That's why the abbreviation for pound is "lb" - it comes from "libra"!

Tips for Accurate Weight Conversion

Precision Tips
  • Use more decimal places for scientific or medical conversions
  • Round to 2 decimal places for everyday use (cooking, shopping)
  • Remember that 1 kg = 2.20462 lb (not exactly 2.2)
  • For baking, be precise - small errors can affect results
  • When converting large quantities, consider significant figures
  • Verify critical conversions (medicine, engineering) with multiple sources
Common Mistakes to Avoid
  • Confusing avoirdupois ounces (28.35g) with troy ounces (31.10g)
  • Mixing up US tons (2000 lb) and metric tons (1000 kg)
  • Forgetting that 1 stone = 14 pounds (not 10 or 16)
  • Using approximate conversions for precise scientific work
  • Not distinguishing between weight (force) and mass
  • Assuming all "ounces" are the same (fluid ounces measure volume)