Weight Converter - Kilograms, Pounds, Grams, Ounces, Stone, Tons, Carats
Free online weight and mass unit converter. Instantly convert between kilograms, pounds, grams, ounces, stone, metric tons, US tons, carats, grains, and more.
Input Weight
Converted Weight
What Is a Weight Converter and Why Do You Need One?
A weight converter (also called a mass converter or weight unit calculator) is an online tool that instantly translates measurements between different units of weight and mass. Weight is a measure of the amount of matter in an object, expressed in units such as kilograms (kg), pounds (lb), grams (g), ounces (oz), stone (st), tons, carats, and grains. Whether you need to convert kilograms to pounds for a fitness goal, convert pounds to kilograms for shipping, convert grams to ounces for cooking, or convert carats to grams for jewelry, this free weight conversion calculator provides accurate, instant results.
Weight measurements are essential across countless everyday activities and professional fields: cooking and baking (grams, ounces, pounds), fitness and body tracking (kg, lb, stone), shipping and logistics (kg, lb, tons), science and chemistry (mg, g, kg), jewelry (carats), and ammunition (grains). Different countries and industries use different unit systems. The United States primarily uses pounds and ounces, while most of the world uses kilograms and grams. The UK uses stone for body weight. Specialized fields use carats for gems and grains for bullets. Without a reliable online weight converter, switching between these systems requires memorizing dozens of conversion factors and risks arithmetic errors.
This free mass unit converter operates entirely within your browser - no data is sent to any server, ensuring your privacy and enabling offline use. It supports 10 weight units spanning metric (kg, g, mg, t), imperial (lb, oz, st, ton), and specialized (grain, ct) systems. Whether you are a chef scaling a recipe, a traveler checking baggage weight, a jeweler evaluating gemstones, a student doing homework, or a professional in any field requiring precise weight conversions, this tool is your go‑to solution.
How to Use This Free Online Weight Converter
Using this kg to lbs converter is simple. Follow these steps to get accurate conversions instantly:
- Enter the value: Type the numeric weight you wish to convert. The tool accepts positive numbers, decimals, and large values up to 10¹².
- Select the source unit: Choose the unit of your input value from the "From Unit" dropdown menu. Options include kilograms, grams, milligrams, metric tons, pounds, ounces, stone, US tons, grains, and carats.
- Select the target unit: Choose the unit you want to convert to from the "To Unit" dropdown.
- View the result: The converted value appears instantly in the output panel. You can copy the result to your clipboard with a single click.
- Use additional features: Click "Swap Units" to reverse the conversion direction, "Clear" to reset all fields, or the fullscreen button for an expanded view.
The pounds to kg converter and all other conversions happen automatically as you type, so you don't need to click a separate convert button unless you prefer manual control. Your recent selections are saved locally for up to 30 days, making it easy to continue your work across sessions.
All Supported Weight Units - Complete Reference Table
Our weight unit converter supports 10 weight units spanning metric, imperial, and specialized systems. Below is a complete reference table showing each unit, its symbol, exact conversion factor to kilograms, and typical applications.
| Unit | Symbol | Value in kg (exact) | Common Uses |
|---|---|---|---|
| Milligram | mg | 1 × 10⁻⁶ | Medicine, supplements, chemistry |
| Grain | grain | 6.479891 × 10⁻⁵ | Ammunition (bullet weight), archery |
| Carat | ct | 0.0002 | Gemstones, diamonds, pearls |
| Gram | g | 0.001 | Cooking, food labeling, small packages |
| Ounce | oz | 0.028349523125 | Cooking, postal weight, body weight (US/UK) |
| Pound | lb | 0.45359237 | Body weight, groceries, gym weights (US/UK) |
| Stone | st | 6.35029318 | Body weight (UK, Ireland) |
| Kilogram | kg | 1 | SI base unit; most common worldwide |
| US Ton | ton | 907.18474 | US industrial and freight weights |
| Metric Ton | t | 1000 | Worldwide standard for large masses |
Understanding Weight Units - From Milligrams to Metric Tons
Metric Units: Kilograms, Grams, Milligrams, Metric Tons
The metric system is the international standard for weight measurement, based on the kilogram (kg). The kilogram is the only SI base unit with a prefix, originally defined by a physical prototype (a platinum‑iridium cylinder) but since 2019 defined by the Planck constant. Metric weight units are decimal‑based: 1 kg = 1000 g, 1 g = 1000 mg, 1 mg = 1000 μg, and 1 metric ton (t) = 1000 kg. This makes conversions simple: to convert kg to g, multiply by 1000; to convert g to kg, divide by 1000. Practical examples: A human weighs 70‑80 kg. A bag of flour is 1 kg (2.2 lb). A paperclip weighs about 1 gram. A grain of salt is about 0.5 mg. A small car weighs about 1 metric ton (1000 kg). The metric system is used for scientific, medical, and most international trade purposes.
Imperial Units: Pounds, Ounces, Stone, US Tons
The imperial system (US customary units) is still the primary system for everyday weight measurements in the United States and partially in the UK and Canada. Conversions are non‑decimal: 1 pound (lb) = 16 ounces (oz), 1 stone (st) = 14 lb, 1 US ton = 2000 lb. This makes manual conversion more complex, so a lbs to kg converteror kg to lbs converter is essential for international communication. Common examples: An adult weighs 150‑200 lb (11‑14 stone). A loaf of bread weighs about 1 lb. A letter weighs around 1 oz. A large SUV weighs about 2.5 US tons. Our tool makes it easy to convert kg to lbs (multiply by 2.20462), convert lbs to kg (multiply by 0.453592), and convert stone to kg (multiply by 6.35029). Since 1959, one pound has been defined as exactly 0.45359237 kilograms, making this conversion exact.
Carats - Precious Gemstones
A carat (ct) is the standard unit of mass for gemstones (diamonds, rubies, sapphires, etc.). One carat equals exactly 200 milligrams (0.2 grams). Carats are further divided into 100 points, so a 0.25 ct diamond is also called a 25‑point diamond. The carat weight of a gemstone is the single most important factor in its price, though cut, color, and clarity also matter. To convert carats to grams, multiply by 0.2. To convert grams to carats, multiply by 5. For example, a 1 carat diamond weighs 0.2 grams, and a 5 carat diamond weighs exactly 1 gram.
Grains - Ammunition and Archery
The grain (gr) is a small unit of mass historically based on the weight of a single grain of barley. One grain equals exactly 64.79891 milligrams (0.06479891 grams). Grains are most commonly used to measure the mass of ammunition (bullets, gunpowder) and arrow shafts. A typical 9mm bullet weighs about 115‑147 grains. To convert grains to grams, multiply by 0.0647989. While specialized, this unit is essential for firearms enthusiasts, reloaders, and archers.
Common Weight Conversions - Quick Reference Formulas
Metric ↔ Metric
- kg → g: multiply by 1,000
- g → mg: multiply by 1,000
- t → kg: multiply by 1,000
- g → kg: divide by 1,000
- mg → g: divide by 1,000
- kg → t: divide by 1,000
Imperial ↔ Imperial
- lb → oz: multiply by 16
- st → lb: multiply by 14
- ton → lb: multiply by 2,000
- oz → lb: divide by 16
- lb → st: divide by 14
Metric ↔ Imperial (Most Common)
- kg → lb: multiply by 2.20462
- lb → kg: multiply by 0.453592
- g → oz: multiply by 0.035274
- oz → g: multiply by 28.3495
- kg → st: multiply by 0.157473
- st → kg: multiply by 6.35029
Specialized Conversions
- ct → g: multiply by 0.2
- g → ct: multiply by 5
- grain → mg: multiply by 64.7989
- mg → grain: multiply by 0.0154324
- kg → ton: divide by 907.185
- ton → kg: multiply by 907.185
Real-World Applications of Weight Conversion
Understanding how to convert between weight unitsis essential across many fields. Here are real-world scenarios where our weight calculator proves invaluable:
Cooking and Recipe Scaling
International recipes often list ingredients in grams, ounces, or pounds. A French pastry recipe might call for 250 g of flour, but a US cook's measuring cups are in ounces and cups. Our grams to ounces converterinstantly provides the equivalent (250 g ≈ 8.8 oz). For larger batches, converting kg to lb helps scale commercial recipes. Baking requires precision - converting accurately ensures successful outcomes.
Fitness and Body Weight Tracking
Gym equipment often lists weights in pounds (US) or kilograms (most other countries). A person tracking their body weight might need to convert stone to kg(UK) or convert kg to lbs (US). Our converter makes it easy to track progress regardless of your preferred unit. A weight loss goal of 10 kg equals 22 lb or 1.57 stone.
Shipping and Logistics
Parcel carriers (UPS, FedEx, DHL) have weight limits in both pounds and kilograms. When shipping internationally, you must know the weight in the destination country's unit. Converting between metric tons and US tons is critical for freight and cargo. A 1000 kg shipment equals 1 metric ton or 1.102 US tons.
Jewelry and Precious Metals
Diamonds are sold by the carat, gold by the troy ounce (though our converter includes standard ounces for reference). A jeweler or precious metals investor frequently needs to convert carats to grams. Our specialized units handle these precisely - a 2 carat diamond weighs 0.4 grams, and a 5 carat diamond weighs exactly 1 gram.
Frequently Asked Questions (FAQ) About Weight Conversion
How do I convert kilograms to pounds?
To convert kg to lbs, multiply the kilogram value by 2.20462. For example, 5 kg × 2.20462 = 11.0231 lb. Conversely, to convert lbs to kg, divide by 2.20462 or multiply by 0.453592. Since 1959, the pound has been defined as exactly 0.45359237 kg, so this conversion is exact.
How many grams are in an ounce?
One standard ounce (avoirdupois) equals exactly 28.349523125 grams. For practical purposes, 1 oz ≈ 28.35 g. To convert ounces to grams, multiply by 28.3495. To convert grams to ounces, divide by 28.3495.
What is the difference between a US ton and a metric ton?
A US short ton equals 2000 pounds (907.185 kg). A metric ton (tonne) equals 1000 kg (2204.62 lb). The metric ton is the international standard for large masses. Our converter includes both for accurate conversions.
How do I convert stone to kilograms?
To convert stone to kg, multiply the stone value by 6.35029. For example, 12 stone × 6.35029 = 76.2035 kg. Stone (st) is primarily used in the UK and Ireland for body weight.
How many carats are in a gram?
One carat equals 0.2 grams, so there are 5 carats per gram. To convert carats to grams, multiply by 0.2. To convert grams to carats, multiply by 5. Diamond weights are always expressed in carats (e.g., a 1 carat diamond weighs 0.2 g).
How accurate is this weight converter?
Our converter uses internationally recognized exact conversion factors (e.g., 1 lb = 0.45359237 kg exactly). It displays results to 6 decimal places, providing excellent precision for cooking, shipping, jewelry, fitness, and scientific applications.
Can I use this weight unit converter offline?
Yes. Once the page has loaded, all conversion logic runs locally in your browser. No internet connection is required, making it reliable anywhere - in the kitchen, at the gym, at the jewelry store, or on a shipping dock.
Why Choose Our Weight Converter Over Others?
- Completely free, no registration required. Unlimited weight conversions without any barriers.
- Privacy‑first design. All calculations are performed locally in your browser. Your data never leaves your device.
- Supports 10 weight units - metric (kg, g, mg, t), imperial (lb, oz, st, ton), and specialized (carat, grain).
- High precision with results to 6 decimal places, suitable for jewelry, scientific, and engineering work.
- User‑friendly features including unit swap, fullscreen mode, one‑click copy, and local save of recent selections.
- Works offline after initial page load. No internet required for conversions.
- Fully responsive design that works on desktops, tablets, and smartphones. Resizable panels on desktop for custom layout.
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