Convert between pounds, kilograms, ounces, grams, stones, and metric tonnes. Free online weight and mass unit converter for any purpose.
Convert between all common weight and mass units with this universal tool. Supports pounds, kilograms, ounces, grams, milligrams, stones, and metric tonnes with instant bidirectional conversion.
Weight conversion is needed daily across cooking, fitness tracking, shipping, science, and international commerce. The US and UK use pounds and ounces for most everyday purposes, while the rest of the world uses kilograms and grams. Health and fitness contexts often require conversion between these systems.
All conversion factors used are internationally standardized. The pound (avoirdupois) is defined as exactly 0.45359237 kilograms, and all other relationships derive from this.
This measurement provides a critical foundation for goal setting and progress tracking, helping you align daily activities with longer-term objectives and meaningful milestones. Integrating this calculation into regular planning habits ensures that work priorities reflect actual data about where time and energy produce the greatest results each week.
This measurement provides a critical foundation for goal setting and progress tracking, helping you align daily activities with longer-term objectives and meaningful milestones.
A single tool for all weight conversions saves time and prevents errors from using approximate factors. Shipping, cooking, fitness, and scientific applications all need precise weight conversion. Regular monitoring of this value helps individuals and teams detect productivity patterns and adjust workflows before small inefficiencies become entrenched and hard to correct.
Conversion via base unit (kilograms): 1 lb = 0.453592 kg (exact: 0.45359237) 1 oz = 28.3495 g = 0.0283495 kg 1 stone = 14 lb = 6.35029 kg 1 g = 0.001 kg 1 mg = 0.000001 kg 1 metric tonne = 1000 kg
Result: 68.04 kg
150 lb × 0.453592 kg/lb = 68.039 kg. This is a common body weight conversion. The exact value is 68.0388555 kg.
The avoirdupois system (pounds, ounces) is the most common weight system in the US and UK for everyday use. The metric system (grams, kilograms) is used internationally and in all scientific contexts. The troy system (troy ounces, troy pounds) is used exclusively for precious metals.
The pound was historically defined by a physical artifact. In 1959, the international yard and pound agreement defined the pound as exactly 0.45359237 kilograms, linking the imperial and metric systems with mathematical precision.
Body weight is perhaps the most personal weight conversion people need. Americans think in pounds, the British often use stone, and the rest of the world uses kilograms. Fitness apps and medical records may require any of these units.
One pound equals 0.453592 kilograms (exactly 0.45359237 kg). This is an internationally defined constant. To convert pounds to kg, multiply by 0.453592.
There are 16 avoirdupois ounces in one pound. This is the standard "ounce" used for everyday weight measurement. Troy ounces (used for precious metals) are different: 12 troy ounces per troy pound.
One stone equals exactly 14 pounds, or approximately 6.35 kilograms. Stone is commonly used in the UK and Ireland for body weight. A person weighing 160 lb is 11 stone 6 pounds.
Mass is the amount of matter (measured in kg/lb) and is constant everywhere. Weight is the force of gravity on that mass and varies by location. On Earth's surface, the distinction is negligible for everyday purposes, and the terms are used interchangeably.
Divide grams by 28.3495 to get ounces. For example, 100 g / 28.3495 = 3.527 oz. Conversely, multiply ounces by 28.3495 to get grams.
A metric tonne (or "tonne") equals 1,000 kilograms or approximately 2,204.6 pounds. It differs from a US short ton (2,000 lb) and a British long ton (2,240 lb). Metric tonnes are the international standard for large-scale weight measurement.