Weight Converter
Conversion Result
Enter a weight value to see conversion results
Common Weight Conversions
| Common Weight | Grams | Ounces | Pounds | Kilograms |
|---|---|---|---|---|
| Butter stick (US) | 113.4 g | 4 oz | 0.25 lb | 0.113 kg |
| Standard letter | 28.35 g | 1 oz | 0.0625 lb | 0.028 kg |
| Bag of flour | 1,360.78 g | 48 oz | 3 lb | 1.361 kg |
| Newborn baby | 3,401.94 g | 120 oz | 7.5 lb | 3.402 kg |
| Large turkey | 9,071.85 g | 320 oz | 20 lb | 9.072 kg |
How Weight Conversion Works
Converting between different weight units is essential for cooking, science, shipping, health tracking, and everyday life. Understanding how grams, kilograms, ounces, pounds, stones, and tons relate to each other helps you work seamlessly across different measurement systems.
Key Concept: Weight conversion is based on fixed mathematical relationships between units. The most important conversions to remember are: 1 kilogram = 1,000 grams, 1 pound = 16 ounces, 1 stone = 14 pounds, and 1 ounce ≈ 28.35 grams.
Core Conversion Formulas
All weight conversions derive from these fundamental relationships:
• 1 lb = 16 oz = 453.592 g = 0.453592 kg
• 1 oz = 28.3495 g = 0.0625 lb
• 1 st = 14 lb = 6.35029 kg
• 1 US ton = 2,000 lb = 907.185 kg
Country-Specific Weight Systems
United States
The United States uses pounds and ounces for most everyday measurements: body weight, food packaging, postal weights, and cooking. Grocery items are sold by the pound, recipes use cups and ounces, and people measure their weight in pounds. Americans need to convert to metric when traveling, using international recipes, or working with scientific measurements.
United Kingdom
The UK uses a mixed system: metric (grams and kilograms) for food and packaging, but stones and pounds for body weight. People describe their weight in stones (1 stone = 14 pounds). Road signs show distances in miles, but fuel is sold in liters. This unique combination creates frequent conversion needs between metric and imperial units.
Canada
Canada officially uses metric but maintains significant imperial usage due to US influence and history. Grocery stores show both grams and ounces/pounds. Recipes may use either system. Body weight is typically measured in pounds, following US convention. This duality means Canadians regularly convert between systems.
Australia
Australia uses metric exclusively for all official measurements. Food is sold in grams and kilograms, body weight is measured in kilograms, and recipes use metric measurements. Australians primarily need imperial conversions when using older recipes, communicating with Americans, or interpreting historical documents.
Weight Unit Comparison Table
| Unit | Equal to | Common Usage | Example Objects |
|---|---|---|---|
| Gram (g) | 0.001 kg 0.0353 oz |
Food, small items, science | Paperclip, dollar bill |
| Kilogram (kg) | 1,000 g 2.20462 lb |
Body weight (metric), produce, parcels | Liter of water, laptop |
| Ounce (oz) | 28.35 g 0.0625 lb |
US cooking, precious metals, mail | Slice of bread, AA battery |
| Pound (lb) | 16 oz 453.59 g |
US body weight, groceries, babies | Loaf of bread, football |
| Stone (st) | 14 lb 6.35 kg |
UK/Ireland body weight | Small dog, microwave |
| US Ton (t) | 2,000 lb 907.185 kg |
US vehicles, shipping, industry | Small car, piano |
Quick Estimates: For rough conversions: 1 kg ≈ 2.2 lb, 1 lb ≈ 0.45 kg, 1 oz ≈ 28 g, 100 g ≈ 3.5 oz. To convert stones to pounds, multiply by 14. To convert pounds to stones, divide by 14.
Common Applications and Use Cases
Cooking and Baking
Recipes from different countries use different measurement systems. European recipes use grams and milliliters, while American recipes use cups, ounces, and pounds. Converting accurately is crucial for successful baking, where precision matters. Our converter helps you adapt any recipe to your preferred measurement system.
Health and Fitness
Tracking body weight, medication dosages, and nutritional information requires accurate conversions. Americans tracking weight loss in pounds need to convert to kilograms for international comparisons. Medication doses are often in milligrams, requiring conversion to grams for understanding.
Shipping and Postage
Postal services charge by weight, often with different unit systems. USPS uses ounces and pounds, while international services may use grams and kilograms. Accurate conversion prevents overpaying or underestimating shipping costs when sending packages internationally.
Science and Education
Students and researchers work with weight measurements across different unit systems. Laboratory measurements use grams and milligrams, while field measurements might use pounds or kilograms. Scientific papers may report findings in different units depending on the journal’s location.
Frequently Asked Questions
What’s the difference between ounces and fluid ounces?
Ounces (oz) measure weight, while fluid ounces (fl oz) measure volume. They’re completely different units. One fluid ounce of water weighs approximately 1.04 ounces (weight), but this varies with density. Never use fluid ounces for weight measurements or vice versa.
Why are there 16 ounces in a pound?
The 16-ounce pound originated in medieval England, possibly from Roman measurement systems. It was standardized in various British systems before being adopted in the US. The number 16 is convenient for division (halving repeatedly: 16, 8, 4, 2, 1), which was useful before calculators.
How accurate do I need to be for cooking conversions?
For most cooking, rounding to the nearest gram or 0.1 ounce is sufficient. For baking, especially with yeast, baking powder, or salt, be more precise. Medication and scientific work require exact conversions. Our converter shows appropriate precision based on the units being converted.
What’s the difference between US tons and metric tons?
US (short) ton = 2,000 pounds = 907.185 kilograms. Metric ton (tonne) = 1,000 kilograms = 2,204.62 pounds. They differ by about 10%. Always specify which ton you’re using, especially in international trade or shipping.
Common Mistakes to Avoid
Mistake 1: Confusing troy ounces with avoirdupois ounces. Troy ounces (31.1g) are for precious metals. Avoirdupois ounces (28.35g) are for everyday items. Using the wrong one creates significant errors with valuable materials.
Mistake 2: Using approximate conversions for precise work. While 1 kg ≈ 2.2 lb works for estimates, the exact conversion is 2.20462. For medication, scientific work, or legal documents, use exact conversions to avoid dangerous or costly errors.
Mistake 3: Forgetting about significant figures. Don’t report more decimal places than your original measurement justifies. If you measure 1 pound on a bathroom scale, converting to 453.59237 grams implies unrealistic precision. Round appropriately.
Practical Examples and Scenarios
Example 1: Cooking with International Recipes
A French recipe calls for 250g of flour. For American cooks: 250g × 0.0353 = 8.82 oz. Since most American recipes use cup measurements, you’d also need to know that 1 cup of flour ≈ 120g, so 250g ≈ 2 cups + 2 tablespoons.
Example 2: Shipping Packages Internationally
You need to ship a 5 lb package from the US to Europe. Convert to metric: 5 lb × 0.453592 = 2.268 kg. European postal services charge by kilograms, so you’d pay for 3 kg (they round up). Knowing this conversion helps estimate costs accurately.
Example 3: Understanding Body Weight Measurements
A British person weighs 11 stone 6 pounds. Convert to pounds: (11 × 14) + 6 = 160 lb. Convert to kilograms: 160 × 0.453592 = 72.57 kg. This helps Americans understand the weight and allows for international health comparisons.
Pro Tip: For quick mental conversions between kilograms and pounds, use the 10% rule: To convert kg to lb, double it and add 10%. Example: 10 kg ≈ 20 + 2 = 22 lb (actual: 22.046 lb). To convert lb to kg, halve it and subtract 10%. Example: 20 lb ≈ 10 – 1 = 9 kg (actual: 9.072 kg).
Historical Context and Modern Standards
The pound has origins in Roman “libra,” hence the “lb” abbreviation. The avoirdupois system (French for “goods of weight”) developed in England for trade. The metric system was created during the French Revolution to standardize measurements based on decimal units.
Today, the International System of Units (SI) uses kilograms as the base unit of mass. Most countries have adopted metric, but the US, Myanmar, and Liberia maintain traditional systems for everyday use. However, even in these countries, science, medicine, and international trade use metric measurements.
Why This Weight Converter Is Essential
Our comprehensive Weight Converter provides instant, accurate conversions with several key advantages:
- All-in-one tool: Converts between 18 different weight units
- Smart categorization: Units organized by usage (metric, imperial, UK, scientific, large)
- Multiple outputs: Shows results in grams, kg, oz, and lb simultaneously
- Quick presets: Common conversions with one click
- Reverse conversion: Swap units instantly
- Adaptive precision: Shows appropriate decimal places for each unit
- Country-aware defaults: Presets based on your likely location
- Instant updates: Results appear as you type
- Mobile optimized: Works perfectly on all devices
- No installation needed: Runs directly in your browser
- Completely free: No signup, no fees, no limitations
- Privacy focused: We don’t store or track your conversions
Whether you’re adapting a recipe, calculating shipping costs, tracking fitness progress, studying science, or just curious about weight measurements, this tool provides reliable results instantly. The clean interface and immediate feedback make it perfect for anyone who needs to convert between weight units without unnecessary complexity.