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Weight Converter - Convert Mass & Weight Units

Last updated: February 2026

Converting between different weight and mass units? Our weight converter handles all common conversions between metric and imperial systems, from milligrams to tons, instantly and accurately.

Table of contents

How to use the weight converter

Converting weight units is straightforward:

  1. Enter the weight value - Type the amount you want to convert
  2. Select the source unit - Choose from kg, lbs, oz, grams, etc.
  3. Choose the target unit - Select your desired output unit
  4. View results - Get instant, precise conversion

Use the swap button (⇅) to quickly reverse your conversion.

Common weight conversions

Metric System

  • 1 kilogram (kg) = 1,000 grams
  • 1 gram (g) = 1,000 milligrams
  • 1 metric ton (tonne) = 1,000 kilograms
  • 1 gram = 0.001 kilograms

Imperial System

  • 1 pound (lb) = 16 ounces
  • 1 ounce (oz) = 28.35 grams
  • 1 stone = 14 pounds
  • 1 ton (US) = 2,000 pounds

Cross-System Conversions

  • 1 kilogram = 2.205 pounds
  • 1 pound = 0.454 kilograms
  • 1 pound = 453.592 grams
  • 1 ounce = 28.35 grams

Understanding weight vs mass

Mass

Mass is the amount of matter in an object. It remains constant regardless of location. Measured in kilograms or grams in the metric system.

Weight

Weight is the force exerted by gravity on a mass. It changes based on gravitational pull. On the Moon, your weight would be about 1/6 of your Earth weight, but your mass stays the same.

Everyday Usage

In daily conversation, we often say "weight" when technically referring to "mass." Our converter handles both terms as they're commonly used interchangeably on Earth.

Weight measurement systems

Metric System (SI Units)

Kilogram (kg)

The base unit of mass. Used for body weight, food, and most everyday items.

Gram (g)

Used for smaller measurements - ingredients, medications, jewelry. One thousandth of a kilogram.

Milligram (mg)

Used for precision measurements - medicine dosages, vitamins. One thousandth of a gram.

Metric Ton (tonne)

Used for large quantities - vehicles, cargo, building materials. Equal to 1,000 kilograms.

Imperial System

Pound (lb)

Primary weight unit in the US. Used for body weight, food, and general measurements.

Ounce (oz)

Smaller imperial unit. Used for recipes, postal rates, and package weights.

Ton (US ton)

Used for large weights - vehicles, equipment. Equal to 2,000 pounds (not the same as metric ton).

Practical applications

Cooking & Baking

  • Recipe conversions - International recipes
  • Ingredient precision - Accurate measurements
  • Portion control - Diet and nutrition
  • Bulk buying - Compare prices per unit

Common Kitchen Conversions

  • Butter: 1 stick = 113 grams = 4 oz
  • Flour: 1 cup ≈ 120-125 grams
  • Sugar: 1 cup ≈ 200 grams
  • Water: 1 cup = 236 ml = 236 grams

Health & Fitness

  • Body weight tracking - Monitor progress
  • Nutrition labels - Understand serving sizes
  • Medication dosages - Follow prescriptions
  • Supplement intake - Protein, vitamins

Shipping & Postal

  • Package weight - Calculate shipping costs
  • Weight restrictions - Airline luggage limits
  • International shipping - Different unit systems
  • Freight calculations - Commercial shipping

Science & Laboratory

  • Chemical measurements - Precise quantities
  • Biology - Specimen weights
  • Physics experiments - Mass calculations
  • Research data - Consistent units

Commercial Use

  • Retail - Product weights
  • Manufacturing - Material quantities
  • Agriculture - Crop yields, livestock
  • Mining - Ore and mineral weights

Frequently Asked Questions

How many pounds are in a kilogram?

One kilogram equals approximately 2.205 pounds. Conversely, one pound equals 0.454 kilograms.

How do I convert kg to lbs quickly?

For a rough estimate, multiply kilograms by 2.2 to get pounds. For 70 kg: 70 × 2.2 = 154 pounds.

What's the difference between a metric ton and a US ton?

A metric ton (tonne) equals 1,000 kg or 2,204.6 pounds. A US ton equals 2,000 pounds or 907.2 kg. The metric ton is slightly heavier.

How many ounces are in a pound?

There are 16 ounces in one pound. This is a defined conversion in the imperial system.

Why do nutrition labels show both grams and ounces?

The US requires food labels to show both metric (grams) and imperial (ounces) measurements to accommodate different user preferences and international standards.

How much does a liter of water weigh?

One liter of water weighs approximately 1 kilogram or 2.205 pounds at standard temperature and pressure. This makes metric conversions convenient.

What's a stone in weight?

A stone is a British imperial unit equal to 14 pounds or about 6.35 kilograms. It's commonly used in the UK for body weight.

How do I convert body weight from kg to lbs?

Multiply your weight in kilograms by 2.205. For example: 70 kg × 2.205 = 154.35 pounds.

Are grams and ounces the same?

No, they're from different systems. 1 ounce = 28.35 grams. Grams are metric, ounces are imperial.

What's the difference between weight and mass?

Mass is the amount of matter (constant everywhere). Weight is the force of gravity on that mass (varies by location). On Earth, we use them interchangeably.

How accurate does weight measurement need to be?

  • Cooking: ±5 grams usually acceptable
  • Medicine: Precise to milligrams
  • Body weight: ±0.1 kg/lb sufficient
  • Shipping: Within carrier specifications
  • Science: Depends on experiment requirements

Can I use this converter for precious metals?

Yes, but note that precious metals are sometimes measured in troy ounces (31.1 grams) which differ from regular ounces (28.35 grams). Our converter uses standard ounces.

Tips for accurate weight measurement

Kitchen Scale Best Practices

  1. Zero/Tare - Reset scale before measuring
  2. Flat surface - Ensure scale is level
  3. Room temperature - Let ingredients settle
  4. Multiple measurements - Verify important weights

Body Weight Tracking

  1. Same time daily - Morning is most consistent
  2. Same scale - Different scales vary
  3. Consistent clothing - Or weigh nude
  4. Track trends - Don't focus on daily fluctuations

Shipping Accuracy

  1. Include packaging - Weigh complete package
  2. Round up - Carriers round to next unit
  3. Verify limits - Check carrier restrictions
  4. Documentation - Keep weight records

Our weight converter provides precision up to 6 decimal places, suitable for virtually all everyday and professional applications.

Expert Insights

Goodbye "Le Grand K"

For 130 years, the kilogram was defined by a physical cylinder of platinum-iridium locked in a vault in Paris ("Le Grand K"). In 2019, scientists redefined it based on Planck's constant, a fundamental constant of quantum physics. Now the kilogram is defined by the universe itself, not a hunk of metal!

Mass vs. Weight

Your Mass is the same everywhere. Your Weight changes with gravity.

  • Earth: 100 kg mass weighs 220 lbs.
  • Mars: 100 kg mass weighs 83 lbs.
  • Space: 100 kg mass weighs 0 lbs (but still has inertia!).

Did You Know? 💡

  • Neutron Star Density: A teaspoon of neutron star material would weigh about 6 billion tons (roughly the combined weight of every human on Earth).
  • The "Slug": In the imperial system, the unit of mass is actually the "slug" (32.2 lbs). The pound is technically a unit of force (weight).
  • Carat: The unit for gems (carat) comes from "carob seeds," which were used as counterweights in ancient markets because of their remarkably consistent size.

References & Further Reading

Weight Converter

Weight Converter

Convert between different units of weight and mass