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.
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.
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.
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.
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.
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Ounces
2,400
Pounds
150
Stone
10.7143
US Tons
0.075
Grams
68,038.8
Kilograms
68.0388