Weight Converter: Convert Between Mass Units
Weight and mass measurements appear everywhere — cooking, shipping, fitness, science, and international trade — often in different units depending on your country. Our free online Weight Converter handles conversions between pounds, ounces, kilograms, grams, milligrams, US tons, metric tonnes, and stones. Whether you're weighing ingredients, calculating shipping costs, or tracking fitness goals, get accurate weight conversions in seconds.
Standard Weight Conversion Reference
| Unit | Equivalent in Kilograms | Other Equivalents |
|---|---|---|
| 1 Milligram (mg) | 0.000001 kg | 0.001 g |
| 1 Gram (g) | 0.001 kg | 1,000 mg | 0.0353 oz |
| 1 Kilogram (kg) | 1 kg | 1,000 g | 2.205 lb |
| 1 Ounce (oz) | 0.02835 kg | 28.35 g | 0.0625 lb |
| 1 Pound (lb) | 0.4536 kg | 16 oz | 453.6 g |
| 1 Stone (st) | 6.350 kg | 14 lb | 224 oz |
| 1 US Ton (short ton) | 907.18 kg | 2,000 lb | 0.907 t |
| 1 Metric Tonne (t) | 1,000 kg | 2,204.6 lb | 1.102 US tons |
| 1 Troy Ounce (oz t) | 0.03110 kg | 31.103 g |
How to Use the Weight Converter
Select your input weight unit (such as pounds), enter the numeric value, and choose your target unit (such as kilograms). The tool instantly displays the equivalent weight. For example, 150 pounds (a typical adult weight) converts to 68.04 kg, 2,400 ounces, or 10.71 stones. The converter supports both small values (milligrams for pharmaceutical doses) and large values (metric tonnes for shipping containers). Results include both US customary and imperial units, plus specialized units like troy ounces for precious metals.
Practical Use Cases for Weight Conversion
Cooking and Baking: Many professional recipes use weight rather than volume for accuracy. Converting 500 g of flour to 17.64 oz or 1.1 lb helps when using US kitchen scales. A European recipe calling for 250 g butter equals about 8.82 oz or approximately 1 cup (if using volume conversion).
Fitness and Body Weight: The UK and Ireland commonly use stones and pounds for body weight, the US uses pounds, and most other countries use kilograms. A person weighing 11 stone 4 lb equals 158 lb or 71.7 kg. Gym equipment is often labeled in kg in Europe and lb in the US — a 20 kg plate equals 44 lb.
Shipping and Postage: Parcel rates depend on weight in either pounds or kilograms. Shipping a 5 kg package equals 11.02 lb. Understanding conversion helps you compare rates across carriers that use different units and avoid surcharges for misstated weight.
International Trade: Goods are traded in metric tonnes globally, but US industries often use short tons. A shipment of 10 metric tonnes equals 11.02 US tons. Agricultural commodities like grain are measured in bushels that convert to specific tonnages depending on the crop.
Precious Metals and Jewelry: Gold, silver, and platinum are weighed in troy ounces, which differ from standard avoirdupois ounces. One troy ounce equals 31.103 g versus 28.35 g for a standard ounce. A gold bar weighing 1 kg equals 32.15 troy ounces.
Worked Example: How the Conversion Math Works
Every result in the converter comes from a single rule: each unit has a fixed number of grams, and the tool multiplies your value by the target unit's gram count and divides by the source unit's gram count. Because the gram is the anchor, converting any unit to any other is always two simple steps, never a remembered chain of steps.
Run the classic body-weight case through the math. Enter 150 pounds. A pound equals 453.59237 grams, so 150 lb is 150 × 453.59237 = 68,038.9 grams. Now divide by the kilogram's 1,000 grams: the result is 68.04 kg, which is the number the tool displays. Convert the same 150 lb to stones by dividing instead by 6,350.29318 grams (one stone), giving 10.71 st — the reading you would see on a UK scale.
- Because the calculator rounds to two decimals, small values like milligrams may show 0.00 — switch to grams for finer readings.
- To convert a 20 kg gym plate to pounds, multiply 20,000 grams by 1 and divide by 453.59237, giving 44.09 lb.
- For troy ounces, the tool uses 31.10348 grams per troy ounce rather than the 28.3495 grams in a standard ounce, which is why gold quotes never match food labels.
Tips for Accurate Weight Conversion
Distinguish between mass and weight — while the terms are used interchangeably in daily life, kilograms measure mass while pounds can measure force. For shipping and cooking, the difference is negligible on Earth. For precious metals, always use the troy ounce option in the converter — a troy ounce is about 9.7% heavier than a standard ounce. When converting body weight, note that US pounds and UK stones use the same pound definition. For volume-to-weight conversions (e.g., cups of flour to grams), see our Cooking Converter. Also check our Volume Converter for liquid measurement conversions.
Keywords: weight converter, kg to lbs, pounds to kilograms, convert weight, ounces to grams, stones to kg, metric tons to US tons, body weight converter, cooking weight conversion, troy ounce, shipping weight calculator
Related Calculators
Use our Weight Converter Guide together with related tools such as Currency Converter, Area Converter, Data Converter to plan more accurately. Each calculator runs instantly in your browser with step-by-step guidance.
Written by the CalcMaster Pro Editorial Team — financial, health, and DIY tools reviewed for accuracy. All calculators run on standard, widely accepted formulas. Always confirm final numbers with a qualified professional for decisions that require official figures.