About This Tool
Weight conversion between pounds, kilograms, ounces, grams, and stones is essential for cooking, fitness tracking, shipping, and international commerce. The US uses pounds and ounces, the UK uses stones for body weight, and the rest of the world uses kilograms and grams. This converter eliminates the confusion by displaying all seven weight units simultaneously. Enter a value in any unit and see every equivalent at once. When you enter a body-weight unit (pounds, kilograms, or stones), the tool highlights the three most relevant conversions for health and fitness contexts. A quick-reference table of common conversion factors is included for those who prefer to memorize the key numbers. All calculations are instant, private, and require no account.
How to Use This Weight Converter
Type a number into the value field and choose your starting unit from the dropdown. The converter immediately shows the equivalent weight in all six other units. Each result appears in its own card for easy reading.
When your starting unit is pounds, kilograms, or stones, the converter adds a dedicated "Body Weight Quick Reference" section that highlights the three units most commonly used for personal weight tracking. This makes it easy to communicate your weight in the system used by your doctor, gym, or travel destination.
The reference table at the bottom lists the most-searched weight conversion factors with precise values. These factors are based on the internationally agreed definition: 1 pound = 453.59237 grams exactly (by the international avoirdupois pound agreement).
Understanding Weight Units
Each weight unit serves different purposes across regions and industries:
- Ounces (oz): Used in the US for food portions, postage, and small measurements. 16 ounces make one pound. Not to be confused with fluid ounces, which measure volume.
- Pounds (lbs): The primary weight unit in the US. Used for body weight, groceries, and shipping. 1 pound = 453.59237 grams exactly.
- Tons (US): Also called "short tons." Equals 2,000 pounds. Used for heavy loads like trucks, construction materials, and bulk commodities in the US.
- Grams (g): The base metric unit of mass. Used worldwide for food labels, jewelry (gold is priced per gram), and scientific measurements.
- Kilograms (kg): The standard unit for body weight, luggage limits, and general measurement outside the US. 1 kg = 2.20462 pounds.
- Metric Tons (t): Also called "tonnes." Equals 1,000 kg or about 2,204.6 pounds. Used internationally for cargo, agriculture, and industrial quantities.
- Stones (st): Used primarily in the UK and Ireland for body weight. 1 stone = 14 pounds. A person weighing 154 pounds weighs 11 stone.
Weight Conversions for Health and Fitness
Body weight tracking often requires converting between systems. Here are common scenarios:
At the doctor: US doctors record weight in pounds. International doctors and most medical research use kilograms. If you know your weight in pounds, divide by 2.2 for a quick kg estimate. For example, 180 lbs / 2.2 = approximately 81.8 kg.
Gym and fitness: Weight plates in US gyms are in pounds (45 lb, 25 lb, 10 lb). Plates in international gyms use kilograms (20 kg, 10 kg, 5 kg). A 20 kg plate is 44.09 lbs. The standard Olympic barbell weighs 20 kg (44.09 lbs).
Airline luggage: US airlines often state limits in pounds (50 lbs per bag), while international carriers use kilograms (23 kg per bag). These are actually similar: 50 lbs = 22.7 kg, and 23 kg = 50.7 lbs.
BMI calculation: BMI requires weight in kilograms and height in meters. The formula is weight (kg) / height (m) squared. If you only know your weight in pounds, converting to kg first is essential for an accurate BMI result.
Metric vs. Imperial Weight Systems
The metric system (grams, kilograms, metric tons) follows a clean decimal structure: 1,000 grams = 1 kilogram, 1,000 kilograms = 1 metric ton. This makes arithmetic straightforward.
The imperial system (ounces, pounds, tons) uses irregular ratios: 16 ounces per pound, 2,000 pounds per US ton. There is no clean multiplier connecting ounces to tons, which makes manual calculations more error-prone.
The stone is unique to the UK and is used almost exclusively for body weight. It equals exactly 14 pounds or approximately 6.35 kg. A person who weighs 12 stone 7 pounds weighs 175 pounds or 79.4 kg. Stones are rarely used outside of personal weight measurement in the UK and Ireland.
In international shipping and trade, the metric ton is the universal standard. The difference between a US ton (2,000 lbs / 907.2 kg) and a metric ton (1,000 kg / 2,204.6 lbs) is about 10%, which can translate to significant dollar amounts in bulk commodity transactions. Always verify which type of "ton" a contract specifies.
Frequently Asked Questions
How many kilograms are in a pound?
One pound equals exactly 0.45359237 kilograms. For quick mental math, divide pounds by 2.2 to get kilograms. Example: 150 lbs / 2.2 = approximately 68.2 kg. For more precision, multiply pounds by 0.4536. The exact conversion is defined by the international avoirdupois pound agreement.
What is the difference between a US ton and a metric ton?
A US ton (short ton) equals 2,000 pounds or approximately 907.2 kilograms. A metric ton (tonne) equals 1,000 kilograms or approximately 2,204.6 pounds. The metric ton is about 10.2% heavier. There is also a "long ton" (imperial ton) used historically in the UK, which equals 2,240 pounds. In international commerce, the metric ton is the standard.
How do stones and pounds work together?
Stones are used in the UK primarily for body weight. One stone equals 14 pounds. Weight is expressed as "X stone Y pounds" where Y is the remainder after dividing total pounds by 14. For example, 165 pounds = 11 stone 11 pounds (because 11 x 14 = 154, and 165 - 154 = 11). To convert from stone to kilograms, multiply by 6.35029.
How do I convert my weight for international travel?
If you know your weight in pounds, divide by 2.205 to get kilograms. If traveling to the UK, divide your pounds by 14 for stone. Common benchmarks to remember: 100 lbs = 45.4 kg, 150 lbs = 68.0 kg, 200 lbs = 90.7 kg. For airline luggage, 50 lbs (common US limit) = 22.7 kg, and 23 kg (common international limit) = 50.7 lbs.
Why is gold weighed differently than regular items?
Gold and other precious metals use the troy weight system, not avoirdupois. A troy ounce equals 31.1035 grams, while a regular (avoirdupois) ounce equals 28.3495 grams. Confusingly, a troy ounce is heavier than a regular ounce, but a troy pound (12 troy ounces = 373.2 g) is lighter than an avoirdupois pound (16 regular ounces = 453.6 g). When gold prices are quoted "per ounce," they always mean troy ounces.
How accurate do weight conversions need to be for cooking?
For baking, precision matters. A difference of 10-20 grams of flour can affect texture. Use the exact conversion: 1 ounce = 28.35 grams. For everyday cooking (soups, stews, sauces), approximate conversions are fine: 1 oz is roughly 30 g, and 1 lb is roughly 450 g. Professional bakers and pastry chefs prefer weighing in grams because it eliminates the imprecision of volume measurements like cups and tablespoons.