Weight Converter

About the Weight Converter

A weight converter transforms measurements between metric units (milligrams, grams, kilograms, metric tonnes), imperial and US customary units (ounces, pounds, US short tons, UK long tons), and specialised units including stones (used in the UK and Ireland for body weight), troy ounces and troy pounds (used for precious metals), and carats (used for gemstones). Weight conversion is needed daily for cooking with international recipes, international shipping and customs declarations, medical dosing, precious metal trading, and fitness tracking. A critical distinction many people miss: the system used for gold, silver, and gemstones — the troy system — uses different ounce and pound values than the everyday avoirdupois system. One troy ounce = 31.1035 grams versus one avoirdupois ounce = 28.3495 grams — a 10% difference that matters enormously when buying precious metals.

How It Works

All conversions route through the kilogram as the SI base unit. Key conversion factors: 1 kg = 2.20462 lbs (avoirdupois). 1 lb = 0.453592 kg = 16 oz. 1 oz (avoirdupois) = 28.3495 g. 1 stone = 14 lbs = 6.35029 kg. 1 metric tonne = 1,000 kg = 2,204.62 lbs. 1 US short ton = 2,000 lbs = 907.185 kg. 1 UK long ton = 2,240 lbs = 1,016.05 kg. Troy system: 1 troy oz = 31.1035 g; 1 troy lb = 12 troy oz = 373.24 g (not 16 oz like avoirdupois). 1 carat = 0.2 g = 200 mg (gemstones only).

Tips & Best Practices

• ✓Body weight in stones and pounds: a 70 kg person = 11 stone 0 lbs (70 / 6.35029 = 11.02 stone). In the UK and Ireland, body weight is commonly expressed in stone and pounds rather than kg or just lbs.
• ✓Gold and silver are always priced in troy ounces — not standard ounces. When a gold price is quoted as "$2,300 per troy ounce," note that a troy ounce is about 10% heavier than a standard ounce.
• ✓International luggage limits: most airlines allow 23 kg (50.7 lbs) for checked bags in economy; 32 kg (70.5 lbs) in business class. Overweight fees are charged per kg or lb over the limit.
• ✓Cooking conversions: US recipes use cups and ounces; UK and European recipes often use grams. 1 cup of flour ≈ 125 g; 1 cup of sugar ≈ 200 g; 1 cup of butter = 227 g = 8 oz = 2 sticks.
• ✓Medication dosing: many drugs are dosed in mg per kg of body weight. A 70 kg patient at 5 mg/kg receives 350 mg. Convert your weight to kg first for accurate self-dosing calculations.
• ✓US vs UK ton confusion: always specify "short ton" (US, 2,000 lbs) or "long ton" (UK, 2,240 lbs) or "metric tonne" (1,000 kg) in international trade documentation — the ambiguity causes costly errors.
• ✓Weightlifting: Olympic barbells are 20 kg (44 lbs) for men and 15 kg (33 lbs) for women. Weight plates in the USA are often in lbs while international competitions use kg plates.
• ✓Gemstone carat: the metric carat (ct) = exactly 0.2 grams. A 1-carat diamond weighs 200 mg. Not to be confused with karat (kt) used for gold purity — 24 karat = pure gold.

Who Uses This Calculator

Home cooks converting between US (cups/ounces) and metric (grams) recipes. International travellers packing luggage to airline weight limits. Precious metal investors converting gold and silver prices between troy ounces and grams. Medical professionals and pharmacists calculating weight-based medication doses. International shippers preparing customs documentation. Fitness enthusiasts tracking body weight across different systems. Jewellers and gemologists working with carat weights.