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Weight Converter

Convert weight and mass measurements between common imperial and metric units. Supports ounces, pounds, stone, US tons, grams, kilograms, and metric tonnes.

Weight (technically "mass" in scientific contexts) conversion between imperial and metric systems is essential for international communication, cooking, medical contexts, shipping, and many trade situations. The US continues using pounds and ounces while most of the world uses metric (grams, kilograms). The UK uses both — pounds for some uses, stones for body weight, kilograms for medical/scientific. Recipe conversions, baby weights, gym equipment, package shipping all routinely require weight conversions.

Key conversions: 1 pound = 453.59 grams = 0.4536 kg; 1 kg = 2.205 lbs; 1 ounce = 28.35 grams; 1 stone (UK body weight) = 14 lbs = 6.35 kg; 1 US ton (short ton) = 2,000 lbs = 907 kg; 1 metric tonne = 1,000 kg = 2,205 lbs. Within metric: 1 kg = 1,000 g; within imperial: 1 lb = 16 oz; 1 stone = 14 lbs; 1 US ton = 2,000 lbs. Notice the imperial system uses 16 (oz/lb), 14 (lb/stone), and 2,000 (lb/ton) — arbitrary multipliers that complicate calculations.

This calculator converts between all common weight units. Use it for: cooking conversions (international recipes), fitness tracking (weight in different systems), shipping cost estimation (lb vs. kg), medical record translation (kg standard medically), or general everyday weight questions. Important context: distinguish weight (gravitational pull) from mass (matter content). In practical everyday use, "weight" and "mass" are interchangeable on Earth. For scientific contexts: mass is the absolute amount; weight depends on gravitational field. For this calculator and most everyday use: weight = mass for practical purposes. Different countries' tons differ: US "short ton" = 2,000 lbs; UK "long ton" = 2,240 lbs; metric tonne = 1,000 kg.

Inputs

Results

Ounces

2,400

Pounds

150

Stone

10.7143

US Tons

0.075

Grams

68,038.8

Kilograms

68.0388

Last updated:

Formula

Weight/mass conversion factors: Imperial system: 1 pound (lb) = 16 ounces (oz) 1 stone = 14 pounds = 224 ounces 1 US ton (short ton) = 2,000 pounds 1 UK ton (long ton) = 2,240 pounds Metric system (decimal-based): 1 gram (g) = 1,000 milligrams (mg) 1 kilogram (kg) = 1,000 grams 1 metric tonne (t) = 1,000 kilograms = 1,000,000 grams Imperial to Metric: 1 ounce = 28.349 grams = 0.02835 kg 1 pound = 453.592 grams = 0.4536 kg 1 stone = 6.350 kg = 6,350 grams 1 US ton = 907.185 kg = 907,185 grams 1 UK ton = 1,016.047 kg Metric to Imperial: 1 gram = 0.03527 oz = 0.002205 lb 1 kg = 35.274 oz = 2.205 lb 1 metric tonne = 2,204.6 lb = 1.102 US ton Example conversions: 150 lbs to kg: 150 × 0.4536 = 68.04 kg 75 kg to lbs: 75 × 2.205 = 165.4 lbs 14 stone to kg: 14 × 6.35 = 88.9 kg 500 g to oz: 500 × 0.03527 = 17.64 oz 1 oz to grams: 28.35 g Common weight references: HUMANS: Average newborn: 7-8 lbs = 3.2-3.6 kg Average toddler (2 yr): 25-30 lbs = 11-14 kg Average child (5 yr): 35-45 lbs = 16-20 kg Average teen (15 yr): 110-150 lbs = 50-68 kg Average adult male US: 200 lbs = 91 kg Average adult female US: 170 lbs = 77 kg ANIMALS: House cat: 8-12 lbs = 3.6-5.4 kg Small dog: 10-30 lbs = 4.5-14 kg Medium dog: 30-60 lbs = 14-27 kg Large dog: 60-100 lbs = 27-45 kg Giant dog: 100-200 lbs = 45-90 kg Adult horse: 800-1,200 lbs = 363-545 kg Adult cow: 1,200-1,500 lbs = 545-680 kg FOOD/COOKING: 1 cup flour: 4.5 oz = 125 g 1 cup sugar (granulated): 7 oz = 200 g 1 stick butter: 4 oz = 113 g 1 large egg: 2 oz = 57 g 1 cup water: 8 fl oz weight ≈ 8 oz = 227 g 1 medium apple: 6 oz = 170 g 1 banana: 4-5 oz = 113-142 g PACKAGING: Standard shipping box small: 1-5 lbs = 0.5-2.3 kg Medium box: 5-30 lbs = 2.3-14 kg Large box: 30-50 lbs = 14-23 kg US Postal regular mail max: 70 lbs = 32 kg USPS Flat Rate envelope: under 70 lbs Most international shipping: 1-30 kg ranges common INDUSTRIAL: Concrete: 145 lbs/cubic ft = 2,322 kg/m³ Steel: 7,850 kg/m³ (490 lbs/cubic ft) Wood (typical): 25-45 lbs/cubic ft (400-720 kg/m³) Water: 8.34 lbs/gallon = 1 kg/liter Conversion mental shortcuts: For quick mental conversions: - 1 kg ≈ 2.2 lbs (precise: 2.2046) - 1 lb ≈ 0.45 kg (precise: 0.4536) - 100 g ≈ 3.5 oz (precise: 3.53) - 1 oz ≈ 28 g (precise: 28.35) For 2-3 decimal precision: use exact factors. Cooking conversion specifics: US recipes: cups, tablespoons, ounces, sometimes pounds European recipes: grams, milliliters, kilograms Common challenges: - Dry vs. liquid measurement (oz can mean weight OR volume) - Different cup sizes (US 8 fl oz vs. UK 10 fl oz) - Liquid measurements often given by volume; metric weight more accurate Recommended for serious baking: - Convert to weights (g) using ingredient-specific densities - More accurate than cup measurements (cup of flour can vary 15% by packing) - Standard recipe books increasingly include weight measurements alongside cups Body weight context: US adult overweight: BMI > 25 = 174 lbs for 5'10" person US adult obese: BMI > 30 = 209 lbs for 5'10" In kg: BMI 25 for 178 cm height: 79 kg BMI 30 for 178 cm height: 95 kg Average weight by category: "Underweight": BMI < 18.5 "Normal": 18.5-24.9 "Overweight": 25-29.9 "Obese": 30+ Pregnancy weight gain: Healthy gain: 25-35 lbs (11-16 kg) By trimester: 1-4 lbs first, 12-14 lbs second, 8-12 lbs third Newborn weights: Average: 7-8 lbs (3.2-3.6 kg) Low birth weight: under 5.5 lbs (2.5 kg) Very low: under 3.3 lbs (1.5 kg) Mass vs. Weight: In physics: Mass: amount of matter (intrinsic property) Weight: gravitational force on mass (depends on gravity) In everyday use: Mass and weight used interchangeably on Earth Difference matters in space (zero gravity = zero weight, but mass unchanged) Unit precision: Cooking: precise to 1 g typically (digital scales) Pharmaceuticals: precise to 0.001 g (1 mg) Industrial: varies by application Shipping: precise to 0.1 lb or 0.05 kg Common weighing situations: Postal: USPS at home with kitchen scale OR post office digital Baby: pediatric scales (digital, precise to 0.1 oz) Gym equipment: typically labeled in kg internationally, lbs US Concert tickets: weight rarely matters (usually electronic now) Shipping: dimensional weight may apply for large/light packages International shipping: US Postal Service: lbs for domestic; can convert for international UPS/FedEx: typically lbs for US to international shipments International services: typically kg Custom forms: complete in both systems often required Customs declarations: weight in both kg and lbs sometimes Unit ambiguity to avoid: Specify "pounds" or "lbs" — "Lb" alone could mean Latvian Lats (currency) Specify "metric ton" or "tonne" vs. "ton" (US short ton) "Ounce" can mean weight (28g) or fluid ounce (29.6 mL) — different things "Pound" usually weight but historically also currency unit (£) For international communications: always state units explicitly.

How to use this calculator

  1. Enter weight value.
  2. Select source unit (ounces, pounds, grams, kilograms, stone, or US ton).
  3. Review automatic conversions across all weight units.
  4. For body weight: kg standard medically; lbs common US daily.
  5. For cooking: grams more precise than ounces; convert recipes for accuracy.
  6. For shipping: 1 kg ≈ 2.2 lbs; 1 lb ≈ 0.45 kg.
  7. For UK body weight: 14 lbs = 1 stone = 6.35 kg.
  8. For mental math: 1 oz ≈ 28 g; 100 g ≈ 3.5 oz.
  9. For precision: use exact factors (1 kg = 2.2046 lbs).
  10. For international: state units explicitly to avoid confusion.
  11. For US tons: 2,000 lbs (different from UK 2,240 or metric 2,205).
  12. For everyday: 1 lb ≈ 0.5 kg memorable approximation.

Worked examples

Body weight conversion

Person weighs 155 lbs. Convert to kg and stone. 155 lbs × 0.4536 = 70.3 kg Or: 155 / 2.205 = 70.3 kg In stone: 155 / 14 = 11 stone 1 lb Different cultural contexts use different units: - US: 155 lbs - Most countries: 70 kg - UK colloquial: 11 stone 1 All same person. Medical records typically use kg internationally; US medical mixed (kg increasingly common). For tracking: choose one system and stick with it; conversions over time confuse trends.

Recipe conversion

European recipe calls for 250g flour, 200g sugar, 100g butter. Convert to US. Flour: 250g × 0.00220 = 0.55 lb. Or use grams directly: ~1.75 cups (cup of flour ~140g). Sugar: 200g = 7.05 oz. About 1 cup of granulated sugar. Butter: 100g = 3.53 oz. About 1 stick of butter (which is 4 oz/113g). For baking precision: use a kitchen scale (digital, $20-$50). Measures in both g and oz, more accurate than cups. Standard conversion guides exist for common ingredients but ingredient-specific. King Arthur Flour, Cook's Illustrated provide detailed conversion charts. Modern recipes increasingly include weights alongside cups for international accessibility and precision.

Shipping comparison

Package weighs 12 lbs. Compare US ground vs. international shipping rates. 12 lbs = 5.44 kg US Postal Service Priority Mail (12 lbs domestic): $25-$40 UPS/FedEx ground (12 lbs domestic): $20-$50 International (12 lbs/5.4 kg): $80-$300+ depending on destination Weight precision in shipping varies by service. Most services charge by pound (or 0.5 kg increments internationally). For international: declarations in both kg and lbs often required; customs forms in receiving country language sometimes. For accurate shipping costs: weigh accurately on calibrated scale; round up to next billing increment.

When to use this calculator

Use this calculator for international communications, recipe conversions (cooking/baking), shipping cost estimation, fitness tracking, medical contexts, or any weight conversion need.

Pair with length-converter, temperature-converter, and other unit calculators.

Important weight conversion considerations:

1. **1 kg ≈ 2.2 lbs.** Quick mental approximation.

2. **Mass and weight interchangeable in everyday use.** Physics distinguishes; daily life doesn't.

3. **Imperial uses arbitrary multipliers.** 16 oz/lb, 14 lb/stone, 2,000 lb/ton — complicated math.

4. **Metric decimal-based.** Multiply/divide by powers of 10.

5. **US tons different from metric.** US short ton = 2,000 lbs; metric tonne = 2,205 lbs.

6. **Specify units explicitly internationally.** "lb" vs. "kg" vs. "stone" avoid confusion.

7. **Body weight context varies.** US daily lbs; medical kg; UK colloquial stone.

8. **Cooking precision matters.** Grams more accurate than cups for serious baking.

9. **Shipping cost depends on weight.** Some carriers use dimensional weight for large light items.

10. **Ounce ambiguous.** Weight (28g) vs. fluid ounce (29.6 mL) different things.

11. **Pregnancy and pediatric care.** Often kg internationally; lbs US.

12. **Scientific consistency.** Use kg for scientific work regardless of locale.

Common mistakes to avoid

  • Confusing fluid ounces and weight ounces. Different units despite same name.
  • Using approximate conversions for precise needs. Cooking 1 oz ≈ 28 g; precision matters for baking.
  • Mixing US and UK tons. US 2,000 lbs; UK 2,240 lbs (long ton). Specify which.
  • Forgetting stone conversion. UK body weight often given in stone (14 lbs).
  • Treating mass and weight identically in physics. Same on Earth; different in space.
  • Cup measurements for baking. Vary 15%+ by packing; weight (g) more reliable.

Frequently Asked Questions

Sources & further reading

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