What is the difference between mass and weight?

Mass is the amount of matter in an object and remains constant everywhere (measured in kilograms or pounds). Weight is the force of gravity on that mass and varies by location (measured in newtons or pounds-force). In everyday conversation, we often use "weight" when we technically mean "mass".

How many pounds are in a kilogram?

1 kilogram equals approximately 2.20462 pounds. This means kilograms are heavier than pounds. This conversion is essential for international travel, shipping, cooking with international recipes, and understanding body weight in different countries.

Why do some countries use stones to measure weight?

The stone is a traditional British unit equal to 14 pounds or about 6.35 kilograms, historically used for weighing goods and people. While most countries have switched to the metric system, the UK still commonly uses stones for measuring body weight, though officially the country has adopted kilograms.

What is a metric ton versus a regular ton?

A metric ton (or tonne) equals 1,000 kilograms or about 2,204.62 pounds. A US ton (short ton) equals 2,000 pounds or about 907 kilograms. A UK ton (long ton) equals 2,240 pounds or about 1,016 kilograms. The metric ton is used in most countries and international shipping.

How do I convert ounces to grams for cooking?

1 ounce equals approximately 28.35 grams. For cooking, a useful approximation is that 1 oz ≈ 30 grams. Many recipes provide measurements in both units, but having a kitchen scale that displays both grams and ounces makes international cooking much easier.

Conversion Calculators

Mass Converter

Convert between weight units including pounds, kilograms, ounces, grams, stones, and more with precision mass calculations for fitness, cooking, shipping, and scientific applications. Features metric and imperial conversions with medical and commercial accuracy.

How to Use the Mass Converter

Use the Mass Converter to between weight units including pounds, kilograms, ounces, grams, stones, and more with precision mass calculations for fitness, cooking, shipping, and scientific applications. Features metric and imperial conversions with medical and commercial accuracy.. Enter your values to get accurate, instant results tailored to your situation.

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Complete Weight & Mass Conversion Guide

Mastering metric and imperial weight units

Expert Tips

Mass vs Weight: Mass is constant everywhere (kg, g). Weight is force due to gravity (varies by location). In daily life, we often use them interchangeably.
Quick Conversions: 1 kg ≈ 2.2 lbs, 1 lb ≈ 0.45 kg, 1 oz ≈ 28 grams. Memorize these for instant estimates without a calculator in daily situations.
Cooking Precision: Baking requires exact measurements. Use grams for precision (flour, sugar). Volume measurements (cups) vary by packing density - weight is more accurate.
Medical Applications: Medication dosing based on body weight. Always convert accurately for safety. kg is standard in medical contexts worldwide.

Weight System Fundamentals — Understanding mass measurement

Metric System (Grams & Kilograms)

Base Unit: Kilogram: SI base unit. Originally based on mass of 1 liter of water. Now defined by physical constants.
Decimal Conversions: 1000 mg = 1 g, 1000 g = 1 kg, 1000 kg = 1 metric ton. Simple powers of 10.
Global Standard: Used worldwide in science, medicine, trade. Essential for international business.
Precision Levels: mg for medicine, g for cooking, kg for body weight, metric ton for shipping.

Imperial System (Pounds & Ounces)

Pound (lb): Primary US weight unit. 1 lb = 16 oz. Used for body weight, food, and most consumer products.
Ounce (oz): Smaller unit for precision. Confusing: fluid oz (volume) ≠ weight oz (mass). Context matters.
Ton (US): 2000 lbs = 1 US ton (different from 2240 lb UK ton and 1000 kg metric ton).
Grain & Dram: Historic units still used in ammunition (grains) and pharmacy (drams). Rarely needed today.

Key Conversions

1 kg = 2.20462 lbs: Fundamental conversion. For mental math: 1 kg ≈ 2.2 lbs is close enough.
1 lb = 453.592 g: Exact: 1 lb = 453.592 g ≈ 454 g for practical purposes.
1 oz = 28.3495 g: Common in cooking. Roughly 28g for quick estimates, 28.35g for precision.
1 metric ton = 2204.62 lbs: Shipping and cargo. Metric ton (1000 kg) vs US ton (2000 lbs) vs UK ton (2240 lbs).

Practical Applications — Real-world weight scenarios

Cooking & Baking

Flour Precision: 1 cup flour = 120-140g depending on packing. Weigh for consistency. Grams eliminate volume ambiguity.
Recipe Conversion: US recipes in cups/oz, European in grams. 1 cup sugar ≈ 200g, 1 cup butter ≈ 227g, 1 cup water ≈ 237g.
Meat Portions: Standard serving: 4-6 oz (113-170g) cooked. Loses 25% weight when cooked. Buy accordingly.
Baking Science: Ratios matter: bread flour 500g = water 350g (70% hydration). Precision affects texture.

Health & Fitness

Body Weight Tracking: Weigh same time daily (morning after bathroom). Fluctuates 2-5 lbs (0.9-2.3 kg) daily. Track trends not fluctuations.
Weight Loss Goals: Healthy: 1-2 lbs/week (0.45-0.9 kg). More than 2 lbs/week = likely muscle loss + water.
Protein Intake: Target: 0.8-1g per pound (1.76-2.2g per kg) for muscle growth. Convert your weight accurately for dosing.
Medication Dosing: Medical doses in mg/kg. 70 kg person (154 lbs) = critical for accurate drug calculation. Never estimate.

Travel & Shipping

Airline Luggage: Checked bag: 50 lbs (23 kg) typical limit. Carry-on: varies by airline. Know limits to avoid fees.
Package Shipping: USPS/UPS pricing by weight. Under 16 oz (454g) = letter rate. Over = package rate. Ounces matter.
International Mail: Most countries use kg. Convert package weight accurately for customs forms and shipping quotes.
Freight & Cargo: Container shipping in metric tons. Truck weight limits vary by country. Cross-border requires both systems.

Frequently Asked Questions

What is the difference between mass and weight?: Mass is the amount of matter in an object and remains constant everywhere (measured in kilograms or pounds). Weight is the force of gravity on that mass and varies by location (measured in newtons or pounds-force). In everyday conversation, we often use "weight" when we technically mean "mass".
How many pounds are in a kilogram?: 1 kilogram equals approximately 2.20462 pounds. This means kilograms are heavier than pounds. This conversion is essential for international travel, shipping, cooking with international recipes, and understanding body weight in different countries.
Why do some countries use stones to measure weight?: The stone is a traditional British unit equal to 14 pounds or about 6.35 kilograms, historically used for weighing goods and people. While most countries have switched to the metric system, the UK still commonly uses stones for measuring body weight, though officially the country has adopted kilograms.
What is a metric ton versus a regular ton?: A metric ton (or tonne) equals 1,000 kilograms or about 2,204.62 pounds. A US ton (short ton) equals 2,000 pounds or about 907 kilograms. A UK ton (long ton) equals 2,240 pounds or about 1,016 kilograms. The metric ton is used in most countries and international shipping.
How do I convert ounces to grams for cooking?: 1 ounce equals approximately 28.35 grams. For cooking, a useful approximation is that 1 oz ≈ 30 grams. Many recipes provide measurements in both units, but having a kitchen scale that displays both grams and ounces makes international cooking much easier.