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Convert pounds (lb) to kilograms (kg) instantly with our free online calculator. Essential for body weight tracking, gym and fitness training, international shipping, travel luggage limits, and medical dosing calculations.
0.453592
Kilograms per Pound
2.20462
Pounds per Kilogram
16 oz
Ounces per Pound
Formula: Kilograms = Pounds × 0.453592
| Pounds (lb) | Kilograms (kg) | Context |
|---|---|---|
| 1 lb | 0.4536 kg | About one stick of butter |
| 5 lb | 2.268 kg | Bag of flour or sugar |
| 10 lb | 4.536 kg | Average newborn baby |
| 20 lb | 9.072 kg | Car tire weight |
| 50 lb | 22.68 kg | Checked baggage (economy limit) |
| 100 lb | 45.36 kg | Standard barbell weight plate |
| 120 lb | 54.43 kg | Lightweight adult |
| 150 lb | 68.04 kg | Average adult body weight |
| 180 lb | 81.65 kg | Athletic male body weight |
| 200 lb | 90.72 kg | Heavy gym lifter |
| 250 lb | 113.40 kg | Heavyweight athlete |
| 300 lb | 136.08 kg | Professional lineman |
| 500 lb | 226.80 kg | Motorcycle weight |
| 1,000 lb | 453.59 kg | Half a metric ton |
| 2,000 lb | 907.18 kg | One short ton (US ton) |
The pound (symbol: lb) is a unit of mass in the imperial and US customary measurement systems. The abbreviation "lb" comes from the Latin word libra, meaning "scales" or "balance." One pound is officially defined as exactly 0.45359237 kilograms by international agreement since 1959 (the International Yard and Pound Agreement). The pound is divided into 16 ounces and is the primary unit of weight measurement in the United States, Liberia, and Myanmar.
The kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). Originally defined in 1795 as the mass of one liter of water at 4 degrees Celsius, the kilogram was redefined in 2019 using the Planck constant for ultimate precision. One kilogram equals 2.20462 pounds or approximately 35.274 ounces. The kilogram is used by the vast majority of the world's population for everyday weight measurements, commerce, science, and medicine.
The relationship between these units is straightforward: 1 lb = 0.453592 kg, or conversely, 1 kg = 2.20462 lb. Understanding this conversion is critical for international travel, fitness training across countries, medical dosing calculations, shipping logistics, and scientific research where weight must be communicated accurately across measurement systems.
The formula to convert pounds to kilograms is: Kilograms = Pounds × 0.453592. Simply multiply the number of pounds by the conversion factor to get the equivalent weight in kilograms.
Question: A person weighs 165 pounds. What is their weight in kilograms for a medical form?
Question: A lifter benches 225 lb. How much is that in kilograms for a powerlifting meet?
Question: A package weighs 48 lb. What is the weight in kg for an international customs form?
For a quick estimate, divide the pounds by 2.2. This gives you a result within 0.2% accuracy. For example: 150 lb / 2.2 = 68.2 kg (exact: 68.04 kg). Another useful trick: halve the pounds, then subtract 10% of that halved number. So 150 / 2 = 75, minus 7.5 = 67.5 kg — close enough for everyday use. For gym weights, remember that a standard 45 lb plate equals about 20.4 kg.
| Description | Pounds | Kilograms |
|---|---|---|
| Newborn baby | 7.5 lb | 3.40 kg |
| Toddler (2 years) | 27 lb | 12.25 kg |
| Child (8 years) | 57 lb | 25.85 kg |
| Teen female (average) | 125 lb | 56.70 kg |
| Teen male (average) | 145 lb | 65.77 kg |
| Adult female (average US) | 170 lb | 77.11 kg |
| Adult male (average US) | 200 lb | 90.72 kg |
| Equipment | Pounds | Kilograms |
|---|---|---|
| Light dumbbell | 5 lb | 2.27 kg |
| Medium dumbbell | 25 lb | 11.34 kg |
| Heavy dumbbell | 50 lb | 22.68 kg |
| Olympic barbell | 45 lb | 20.41 kg |
| Standard plate (each side) | 45 lb | 20.41 kg |
| Bench press (1 plate per side) | 135 lb | 61.23 kg |
| Squat (2 plates per side) | 225 lb | 102.06 kg |
| Deadlift (3 plates per side) | 315 lb | 142.88 kg |
| Elite squat (4 plates per side) | 405 lb | 183.71 kg |
| Item / Limit | Pounds | Kilograms |
|---|---|---|
| Carry-on luggage limit | 15–22 lb | 7–10 kg |
| Economy checked bag limit | 50 lb | 22.68 kg |
| Business class checked bag | 70 lb | 31.75 kg |
| Small parcel (USPS) | 13 lb | 5.90 kg |
| Medium package (FedEx) | 50 lb | 22.68 kg |
| Large freight box | 150 lb | 68.04 kg |
| International pallet max | 2,200 lb | 997.90 kg |
Medical professionals worldwide use kilograms for body weight. Drug dosages, BMI calculations, anesthesia levels, and nutritional plans are all based on kilograms. Patients who know their weight only in pounds must convert accurately for proper medical care, especially when traveling or visiting international clinics.
Olympic weightlifting, powerlifting, and CrossFit competitions use kilograms exclusively. Gym-goers traveling internationally encounter metric weight plates (5, 10, 15, 20, 25 kg). Converting your personal records and training weights from pounds to kilograms ensures consistent progressive overload across any gym in the world.
Customs declarations, freight invoices, and international shipping labels require weights in kilograms. Misreporting package weight due to conversion errors can result in customs delays, additional surcharges, or rejected shipments. Accurate lb-to-kg conversion is essential for smooth cross-border logistics.
International airlines set baggage weight limits in kilograms. A US traveler packing a 50-pound suitcase needs to know that equals 22.68 kg to check against a 23 kg limit. Exceeding the limit by even 0.5 kg can mean costly excess baggage fees ranging from $50 to $200 per bag.
Weight-based medications like chemotherapy drugs, pediatric antibiotics, and anesthetics are dosed in milligrams per kilogram of body weight. A conversion error between pounds and kilograms could mean giving a patient double or half the intended dose, with potentially life-threatening consequences.
International recipes, nutritional databases, and food labels commonly use grams and kilograms. When tracking macronutrients or following meal plans from international sources, converting between pounds and kilograms helps maintain accurate portion sizes and caloric intake calculations.
Four decimal places is accurate enough for body weight and shipping. Use six decimal places for scientific or pharmaceutical calculations.
This gives a result within 0.2% of the exact answer. Great for quickly estimating body weight or luggage weight at the airport.
Memorizing a few anchor points makes it easy to estimate nearby values without a calculator.
Multiplying by 2.2 converts kilograms to pounds, not the other way around. For lb to kg, you must divide by 2.2 or multiply by 0.453592.
In everyday use they are equivalent on Earth, but in engineering and physics contexts, lb is mass while lbf is a force unit. For weight conversion, standard pounds (lb) to kilograms (kg) is correct.
This common mistake overestimates by about 10%. One pound is actually 0.4536 kg, not 0.5 kg. Using 0.5 for a 200 lb person gives 100 kg instead of the correct 90.7 kg — a 9.3 kg error.
One pound equals exactly 0.453592 kilograms (or more precisely, 0.45359237 kg). This is an internationally standardized conversion factor established by the 1959 International Yard and Pound Agreement. To convert any number of pounds to kilograms, multiply by 0.453592.
Divide the number of pounds by 2.2 for a quick estimate. For example, 150 lb / 2.2 = roughly 68 kg (exact: 68.04 kg). Another trick: halve the pounds, then subtract 10% of that result. So 150 / 2 = 75, minus 7.5 = 67.5 kg — close to the exact answer.
The United States uses pounds for weight plates and body weight, while most other countries use kilograms as part of the metric system. Olympic and international powerlifting competitions use kilograms exclusively. Gym-goers traveling internationally need to convert between systems to maintain consistent training loads.
Multiply your weight in pounds by 0.453592. For example, a 180-pound person weighs 180 × 0.453592 = 81.65 kg. Most medical and scientific contexts worldwide use kilograms for body weight, so this conversion is important for international travel and healthcare.
Most international airlines set checked baggage limits at 23 kg (about 50.7 lb) for economy class and 32 kg (about 70.5 lb) for business/first class. Carry-on limits are typically 7-10 kg (15.4-22 lb). US domestic flights often express limits in pounds (50 lb checked, which equals 22.68 kg).
Not exactly. One kilogram equals approximately 2.20462 pounds. The commonly used 2.2 factor is a rounded approximation that introduces a small error of about 0.2%. For everyday use this is fine, but for precise scientific, medical, or shipping calculations, use the exact factor: 1 kg = 2.20462 lb.
Many medications are dosed based on body weight in kilograms (mg per kg). If a patient reports their weight in pounds, healthcare providers must convert to kilograms for accurate dosing. An error in conversion could lead to under-dosing (ineffective treatment) or over-dosing (potential toxicity), making precision critical.
International shipping carriers like FedEx, UPS, and DHL accept weight in both pounds and kilograms but use kilograms for international documentation and customs declarations. Shipping rates are often calculated per kilogram internationally. Accurate conversion prevents customs delays and ensures correct freight charges.
A pound (lb) is an imperial unit of mass equal to 0.453592 kg. A kilogram (kg) is the SI base unit of mass, defined by the Planck constant since 2019. One kilogram is about 2.205 times heavier than one pound. Kilograms are used by the vast majority of the world, while pounds are primarily used in the US, Liberia, and Myanmar.
This calculator uses the internationally recognized conversion factor of 1 lb = 0.45359237 kg. For medical dosing, pharmaceutical calculations, and official documentation, always verify conversions with a qualified professional or refer to your jurisdiction's official measurement standards.