Weight Calculator
Convert weight between pounds, kilograms, grams, ounces, stone, and metric tons. Calculate weight on different planets. Convert between weight units (kg, g, lb, oz). Calculate weight from volume and density for shipping, cooking, and scientific purposes.
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Weight Calculator: Convert Between All Weight Units
The Weight Calculator converts weight values between all major units of measurement — including pounds (lbs), kilograms (kg), grams (g), ounces (oz), stone (st), and metric tons (t) — instantly and accurately. It also shows your weight as it would feel on different planets, applying each planet's unique gravitational acceleration to reveal the fascinating relationship between mass and gravitational weight.
Weight conversion is one of the most common everyday calculations worldwide. Whether you're a traveler adapting to different unit systems, a chef following an international recipe, an athlete tracking body weight across different scales, or a shipping professional calculating freight costs, knowing how to convert between weight units is essential.
Our calculator provides simultaneous conversion to all major units with a single input, eliminating the need to perform multiple calculations or remember complex conversion factors. Enter your weight once, and see all conversions at once.
💡 Quick Reference: The most common conversion to remember: 1 kg = 2.20462 lbs (often approximated as 2.2). For quick mental math: divide pounds by 2.2 to get approximate kg, or multiply kg by 2.2 to get approximate lbs.
When to Use This Weight Converter
✈️ International Travel
Convert airline luggage limits between pounds and kilograms. US airlines often state limits in lbs (50 lbs = 22.68 kg), while international airlines use kg.
🍳 Cooking & Baking
Convert recipe ingredients between grams, ounces, and pounds. International recipes use different unit standards — European recipes favor grams, American recipes favor ounces and cups.
💪 Fitness & Health
Track body weight on scales using different unit systems. Convert gym equipment weight plates between kg (standard plates) and lbs (US plates). Monitor weight loss goals in preferred units.
📦 Shipping & Logistics
Convert package weights to determine shipping costs. USPS uses pounds and ounces, while international shipping and FedEx/UPS international services use kilograms.
🔬 Science & Engineering
Convert between SI units (grams, kilograms) and imperial units (ounces, pounds) for lab measurements, material specifications, and engineering calculations.
🏪 Commerce & Trade
Convert commodity prices between metric tons and short tons. International commodity markets (oil, metals, grain) use metric tons; US domestic markets often use short tons.
Weight Unit Conversion Formulas
All weight unit conversions are based on exact or defined conversion factors. Here are the key formulas:
Kilograms ↔ Pounds
lbs = kg × 2.20462
kg = lbs × 0.453592
Kilograms ↔ Grams
g = kg × 1,000
kg = g ÷ 1,000
Pounds ↔ Ounces
oz = lbs × 16
lbs = oz ÷ 16
Pounds ↔ Stone
stone = lbs ÷ 14
lbs = stone × 14
Kilograms ↔ Metric Tons
t = kg ÷ 1,000
kg = t × 1,000
Grams ↔ Milligrams
mg = g × 1,000
g = mg ÷ 1,000
Weight Unit Conversion Table
| Unit | Pounds (lb) | Grams (g) | Ounces (oz) | Stone | Metric Ton |
|---|---|---|---|---|---|
| 1 kilogram (kg) | 2.20462 | 1,000 | 35.274 | 0.157 | 0.001 |
| 1 pound (lb) | 1 | 453.592 | 16 | 0.0714 | 0.000454 |
| 1 ounce (oz) | 0.0625 | 28.3495 | 1 | 0.00446 | 0.0000283 |
| 1 stone | 14 | 6,350.29 | 224 | 1 | 0.00635 |
| 1 metric ton (t) | 2,204.62 | 1,000,000 | 35,274 | 157.47 | 1 |
Worked Examples
Example 1: Airline Luggage Check (Pounds to Kilograms)
Scenario: Your bag weighs 48 lbs. The airline allows 23 kg. Is it within the limit?
Convert: 48 lbs × 0.453592 = 21.77 kg
Result: 21.77 kg < 23 kg — you're within the weight limit! ✓
Example 2: Body Weight for a UK Medical Record
Scenario: You weigh 165 lbs. Express in stone and pounds (UK standard).
Convert: 165 ÷ 14 = 11 stone remainder 11 lbs → 11 stone 11 lbs
Also: 165 lbs × 0.453592 = 74.84 kg
Example 3: Recipe Conversion (Grams to Ounces)
Scenario: A French recipe calls for 350 g of flour. How many ounces?
Convert: 350 g ÷ 28.3495 = 12.35 oz
Practical: Use 12 oz (≈ 340 g) — close enough for baking.
Example 4: Shipping Package (Ounces to Kilograms)
Scenario: Package weighs 45 oz. International carrier needs weight in kg.
Convert: 45 oz × 28.3495 g/oz = 1,275.7 g ÷ 1,000 = 1.276 kg
Shortcut: 45 oz ÷ 35.274 = 1.275 kg
Example 5: Commodity Trade (Short Tons to Metric Tons)
Scenario: A US steel mill produces 5,000 short tons. Convert to metric tons for international pricing.
Convert: 5,000 short tons × 2,000 lbs/short ton = 10,000,000 lbs × 0.453592 kg/lb = 4,535,920 kg ÷ 1,000 = 4,535.9 metric tons
Shortcut: 1 short ton = 0.907185 metric tons → 5,000 × 0.907185 = 4,535.9 t
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Weight on Other Planets
Your weight depends on the gravitational acceleration of the planet you're on. Your mass stays the same, but the gravitational force changes. Here's how a 70 kg (154 lb) person's weight varies across the solar system:
| Planet/Body | Gravity (m/s²) | Weight of 70 kg person | Relative to Earth |
|---|---|---|---|
| Mercury | 3.70 | 25.9 kg / 57.1 lbs | 37% |
| Venus | 8.87 | 62.1 kg / 137 lbs | 90% |
| Earth | 9.81 | 70 kg / 154 lbs | 100% |
| Moon | 1.62 | 11.6 kg / 25.5 lbs | 17% |
| Mars | 3.73 | 26.6 kg / 58.7 lbs | 38% |
| Jupiter | 24.79 | 176.9 kg / 390 lbs | 253% |
| Saturn | 10.44 | 74.5 kg / 164 lbs | 106% |
Note: "Weight" here is shown as an equivalent mass comparison (how much you'd "feel like" you weigh). True scientific weight would be in Newtons.
Common Mistakes When Converting Weight
❌ Confusing Grams and Milligrams
Consequence: In medication dosing, confusing mg and g can be fatal. 500 mg ≠ 500 g (factor of 1,000 difference).
✓ Solution: For medications and small quantities, always specify and double-check units. 1 g = 1,000 mg; 1 mg = 0.001 g.
❌ Using Troy Ounce Instead of Avoirdupois Ounce
Consequence: Precious metals (gold, silver) use troy ounces (31.1035 g), not avoirdupois ounces (28.3495 g). Using the wrong ounce introduces a 9.7% error.
✓ Solution: For gold and silver: use troy ounces (ozt). For food, shipping, and everyday goods: use avoirdupois ounces (oz).
❌ Confusing Short Tons and Metric Tons
Consequence: US short ton = 2,000 lbs = 907 kg. Metric ton = 1,000 kg = 2,205 lbs. These differ by about 10% — significant in commodity trading.
✓ Solution: Always specify which ton: short ton (US), long ton (UK), or metric ton (tonne, international). Use metric tons for all international trade and scientific work.
Tips and Best Practices
- •Memorize the key factor: 1 kg ≈ 2.2 lbs (exact: 2.20462). This approximation is accurate enough for most practical purposes and enables quick mental calculations.
- •Use grams for precision: For small quantities (food ingredients, medications, chemistry), always work in grams or milligrams. Converting between grams and ounces introduces rounding errors.
- •Label your units clearly: In technical documents, always write units explicitly. Write "25 kg" not just "25." Ambiguous units have caused engineering disasters (e.g., the Mars Climate Orbiter crash in 1999 was caused by mixing lbf·s and N·s).
- •Convert at the end, not during: Perform all calculations in one unit system and convert only the final result. Intermediate conversions compound rounding errors.
Frequently Asked Questions About Weight Conversion
▶How do I convert kilograms to pounds?
Multiply by 2.20462. Example: 75 kg × 2.20462 = 165.35 lbs. To convert lbs to kg: multiply by 0.453592.
▶What is the difference between weight and mass?
Mass (kg, g) is constant everywhere. Weight is gravitational force (W = mg). On Earth's surface, a 1 kg mass has a weight of 9.81 N (≈ 2.2 lbf).
▶How many grams are in an ounce?
1 avoirdupois ounce = 28.3495 grams. 1 troy ounce (precious metals) = 31.1035 grams. 16 oz = 1 lb = 453.592 g.
▶What is a stone in weight?
1 stone = 14 pounds = 6.35029 kg. Used primarily in UK/Ireland for body weight. 11 stone 4 lbs = (11 × 14) + 4 = 158 lbs = 71.67 kg.
▶How do I convert grams to milligrams?
Multiply by 1,000. 1 g = 1,000 mg. To convert mg to g: divide by 1,000. Example: 500 mg = 0.5 g.
▶How many pounds in a metric ton?
1 metric ton (tonne) = 1,000 kg = 2,204.62 lbs. US short ton = 2,000 lbs = 907.18 kg. UK long ton = 2,240 lbs = 1,016.05 kg.
▶What is my weight on the Moon?
Moon gravity = 1.62 m/s² (about 1/6 of Earth's 9.81 m/s²). Divide your Earth weight by 5.98 to get your Moon weight. A 154 lb (70 kg) person weighs about 25.7 lbs on the Moon.
▶How much does a person weigh on other planets?
Weight varies with gravity. Jupiter's gravity (24.79 m/s²) is 2.53× Earth's, so you'd feel 2.53× heavier. Mars gravity (3.73 m/s²) is 0.38× Earth's, so you'd feel 62% lighter.
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Conclusion
Weight conversion is a fundamental skill in an internationally connected world where different countries, industries, and scientific disciplines use different measurement systems. Whether converting your body weight from pounds to kilograms for a European gym, scaling a recipe from grams to ounces, or calculating freight charges across metric and imperial systems, this weight calculator handles all conversions instantly and accurately.
The key to accurate weight conversion is using the exact conversion factors (1 kg = 2.20462 lbs, not just 2.2) and being clear about which type of unit you're using — especially for tons (short, long, or metric) and ounces (avoirdupois vs. troy). This calculator eliminates unit confusion by showing all conversions simultaneously from a single input.
🏋️ Health Applications: Pair this with the BMI Calculator to assess your body mass index, or the Ideal Weight Calculator to find your target weight range in both pounds and kilograms.
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