Weight Converter
Convert weight between common units.
Weight Conversion
Quick Conversions
All Conversions
| Unit | Value | System | Action |
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Weight Categories & Comparisons
Conversion History
BMI Calculator
Weight Measurement Systems
Metric System:
- • Kilogram (kg): Base unit of mass
- • Gram (g): 1/1000 of a kilogram
- • Tonne (t): 1000 kilograms
- • Milligram (mg): 1/1000 of a gram
- • Used worldwide, scientific standard
Imperial System:
- • Pound (lb): 16 ounces
- • Ounce (oz): 1/16 of a pound
- • Stone (st): 14 pounds (UK)
- • Ton: 2000 lbs (US), 2240 lbs (UK)
- • Primarily used in US and UK
Special Units:
- • Troy Ounce: Precious metals (31.1g)
- • Carat: Gemstones (0.2g)
- • Grain: Bullets, medicine (64.8mg)
- • Atomic Mass Unit: Molecular weight
- • Specialized applications
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Learn more — open a section when you need details
The Weight Converter is a comprehensive mass conversion tool that converts weight values across multiple measurement systems including metric units (grams, kilograms, milligrams, metric tons), imperial units (ounces, pounds, US short tons), UK imperial units (UK long tons), precious metal units (troy ounces, pennyweights used for jewelry and precious metals), and special units for various weight conversion needs. It uses grams as the base conversion unit for all calculations ensuring mathematical consistency. The tool provides a comprehensive all-units comparison table showing weight equivalents across all supported units, contextual weight comparisons with real-world objects for scale understanding, a lightweight BMI (Body Mass Index) calculator panel for health-related weight calculations, and history/export functionality for conversion audits and documentation. It processes all conversions entirely locally in your browser, ensuring privacy and fast performance without server uploads. Extreme weight magnitudes automatically switch to scientific notation for legibility while preserving full calculation precision. The tool is practical for scientific calculations, logistics and shipping operations, food and retail measurements, jewelry and precious metals trading, health and fitness tracking, or any scenario requiring accurate, consistently rounded weight values across different measurement systems for precise weight conversion and standardization.
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Input a numeric weight value in the input field and choose the "From" unit (source weight unit like grams, pounds, ounces, etc.) and "To" unit (target weight unit for conversion) from the dropdown menus, as weight value and unit selection determine conversion calculation and result display.
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Use "Quick Conversions" buttons for common weight unit pairs (kg ↔ lb, oz ↔ g, etc.) to instantly convert between frequently used weight combinations without manual unit selection, or click "Swap Units" button to reverse conversion direction quickly for efficient bidirectional conversions.
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Review the "All Conversions" comparison table displaying weight equivalents across all supported units converted from the same input value, enabling quick reference and comparison of weight values in multiple unit systems simultaneously for comprehensive weight unit understanding.
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Open "Weight Categories" or comparison section if available to view real-world weight comparisons and context (e.g., weight of common objects, animals, items) for understanding weight magnitudes and scale, enabling practical weight comprehension through familiar reference points and contextual comparisons.
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Use the BMI (Body Mass Index) panel if available to relate weight (mass) and height measurements for health-related calculations, entering height and weight to calculate BMI for health assessment, or export conversion results and share weight calculations as needed for documentation and communication.
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Verify conversion accuracy by checking displayed results against known weight conversion relationships (e.g., 1 kilogram = 2.20462 pounds, 1 ounce = 28.3495 grams), as accuracy verification ensures conversion correctness and catches potential errors requiring result validation especially for critical weight calculations.
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Copy converted weight values to clipboard for immediate use in documents, calculations, or communications, or use export functionality to save weight conversions as CSV file for spreadsheet integration, audit trails, or documentation requiring persistent weight conversion records.
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Review scientific notation for extreme weight values (very large or very small), as scientific notation maintains precision while enabling readable representation of extreme magnitudes requiring understanding that scientific notation preserves accuracy for weights beyond normal decimal notation range.
Logistics and shipping weight conversion
Convert between kilograms (kg) and pounds (lb) or short tons (st) when printing shipping labels, preparing customs documentation, or calculating shipping costs for different regions requiring weight unit standardization across international shipping and logistics operations.
Laboratory and industrial weight measurements
Work precisely with milligram (mg), gram (g), and kilogram (kg) measurements for laboratory work, then convert to ounces (oz) or pounds (lb) for supplier documentation, quality control reports, or industrial specifications requiring accurate weight conversions between metric and imperial systems.
Jewelry and precious metals trading
Convert grams to troy ounces and pennyweights for jewelry pricing, precious metals trading, or jewelry manufacturing, as jewelry industry uses troy weight system (troy ounce = 31.1035g) requiring accurate precious metal weight conversions for pricing and trading operations.
Diet, fitness, and health tracking
Track body weight in familiar units (pounds or kilograms) and estimate BMI (Body Mass Index) quickly using integrated BMI calculator, enabling health tracking and fitness monitoring requiring accurate weight conversions and health-related weight calculations for personal health management.
Food and retail weight measurements
Convert food weights between metric (grams, kilograms) and imperial (ounces, pounds) for recipe preparation, food labeling, retail pricing, or food service operations, enabling accurate food weight conversions for cooking, retail, and food industry applications requiring weight standardization.
Scientific research and academic applications
Convert weight measurements for scientific experiments, research documentation, or academic assignments requiring precise weight conversions between metric and imperial systems for scientific accuracy and academic reporting requiring standardized weight units in research and education.
Manufacturing and production weight standards
Convert weight values for manufacturing specifications, production standards, or quality control measurements requiring accurate weight conversions between different unit systems for industrial applications, manufacturing processes, or production quality assurance requiring precise weight standardization.
International trade and commerce weight conversion
Convert weight measurements for international trade, commerce, or business transactions requiring weight unit standardization across different countries and regions, enabling accurate weight conversions for international business operations, trade documentation, or commercial transactions requiring consistent weight measurements.
Use exact conversion standards (1 avoirdupois ounce = 28.3495 grams, 1 pound = 453.592 grams, 1 troy ounce = 31.1035 grams) for precise calculations, as exact standards ensure mathematical accuracy requiring precise conversion factors rather than approximate values for critical weight calculations and conversions.
Pick suitable precision levels for weight conversions: use more decimal places for small weights (milligrams, grams) and fewer decimals for large weights (tons, pounds), as appropriate precision matches measurement accuracy and improves result readability requiring precision selection matching weight magnitude and measurement accuracy.
Prefer grams as internal base unit for consistent mathematical calculations in multi-step conversions, as converting through grams maintains maximum precision throughout conversion chains, reducing cumulative rounding errors that occur when converting through intermediate units requiring base unit usage for accurate multi-step weight conversions.
Label US short tons vs UK long tons clearly to avoid confusion, as US short ton (2000 pounds) differs significantly from UK long ton (2240 pounds), causing substantial conversion errors (approximately 10% difference) if wrong ton definition is used requiring clear specification of ton type (short vs long) for accurate weight conversions.
Export weight conversions as CSV file to attach to specifications, documentation, or records for audit trails and documentation, as CSV export enables spreadsheet integration and persistent weight conversion records requiring export functionality for comprehensive weight conversion documentation and record-keeping.
Understand difference between troy ounces (precious metals) and avoirdupois ounces (common weight), as troy ounce (31.1035g) differs from avoirdupois ounce (28.3495g), causing significant errors (approximately 10% difference) if wrong ounce type is used requiring correct ounce selection based on use case (precious metals use troy, common weight uses avoirdupois).
Verify conversion accuracy against known reference points (freezing point comparisons, standard weights, well-known conversions), as reference point validation catches conversion errors and ensures accuracy requiring spot-checking conversions against well-known weight relationships to verify converter accuracy and reliability.
Consider weight unit context when selecting units (metric for science, imperial for US, troy for jewelry), as different industries and regions use different weight systems requiring appropriate unit selection matching industry standards and regional conventions for accurate weight communication and professional weight conversion practices.
Confusing US short ton with UK long ton, when US short ton (2000 lbs) differs from UK long ton (2240 lbs), causing significant conversion errors (about 10% difference) if wrong ton definition is used, requiring clear specification of ton type (short vs long) for accurate weight conversions.
Rounding intermediate values before final conversion, when intermediate rounding introduces cumulative errors in multi-step conversions, causing inaccurate final results requiring full precision calculations through base unit (grams) before final rounding for accurate conversions.
Using kitchen measures interchangeably with mass units (volume ≠ mass), when volume measurements (cups, tablespoons) are confused with mass units (grams, ounces), causing conversion errors especially for ingredients with different densities requiring understanding that volume and mass are different measurement types with different conversion factors.
Excluding unit symbols from shared results, causing ambiguity, when unit-less numbers are shared without context, causing confusion about measurement scale or incorrect assumptions about units requiring inclusion of unit symbols or explicit unit specification in all weight conversion results.
Not understanding troy vs avoirdupois ounce differences for precious metals, when troy ounce (31.1035g) differs from avoirdupois ounce (28.3495g) used for common weight, causing significant errors (about 10% difference) in jewelry or precious metal conversions requiring correct ounce type selection based on use case (precious metals use troy, common weight uses avoirdupois).
Mixing metric and imperial units without clear conversion path, when direct conversions between non-standard unit pairs introduce errors, causing inaccurate results requiring conversion through base unit (grams) for consistent and accurate weight conversions across all unit systems.
Using approximate conversion factors instead of precise standards, when approximate values (e.g., "1 pound = 450g" instead of 453.592g) introduce errors that compound in calculations, causing inaccurate conversions requiring use of exact conversion standards for precise weight calculations.
Not verifying conversion accuracy against known reference points, when conversion results aren't checked against well-known values (e.g., 1 kg = 2.20462 lbs), causing undetected errors requiring validation of conversions using reference points to ensure accuracy.
Converting extremely large or small weights without scientific notation, when very large magnitudes (tons) or very small magnitudes (milligrams) become unreadable in standard decimal notation, causing confusion or error-prone values requiring scientific notation or appropriate unit selection for extreme weight values.
Ignoring precision requirements for different use cases, when scientific or industrial applications need high precision while casual conversions can tolerate rounding, causing inappropriate precision if conversion precision doesn't match application requirements requiring precision selection based on use case accuracy needs.
Not considering weight category context for appropriate unit selection, when different contexts (logistics, jewelry, laboratory) require different unit systems or precision, causing inappropriate conversions if context-specific requirements aren't considered requiring unit selection matching application context (logistics: kg/lb, jewelry: grams/troy ounces, lab: mg/g).
Assuming all weight conversions work identically regardless of substance, when weight conversions are universal (mass doesn't depend on material), but unit preferences vary by context, causing unit selection issues rather than conversion errors requiring understanding that weight conversion factors are universal but unit system preferences vary by application domain.
Standards are precise; output is rounded for display with controlled decimals.
Copy individual values or export history; table values can be copied from the page.
Troy is for precious metals (31.1035 g/oz). Avoirdupois is common mass (28.3495 g/oz).
No, it's a rough indicator. Consult health professionals for diagnosis.
US short ton equals 2000 pounds (907.185 kg), while UK long ton equals 2240 pounds (1016.047 kg). The difference is about 10%. Use short ton for US measurements and long ton for UK measurements. For international shipping, specify which ton standard applies to avoid confusion in logistics and documentation.
Scientific notation displays very large or very small weights readably without losing precision. For example, converting micrograms to tons produces extremely small decimal numbers. Scientific notation preserves full precision while maintaining readability for extreme weight values that would be unreadable in standard decimal format.
This tool converts mass/weight units, not volume. Volume measurements (cups, tablespoons, liters) measure space, while weight units (grams, ounces, pounds) measure mass. The relationship depends on density—a cup of water weighs different than a cup of flour. For volume-to-weight conversions, you need density information specific to the material being measured.
Conversions use precise international standards (e.g., 1 pound = 453.59237 grams exactly). Display values are rounded for readability, but full precision is maintained internally. For critical applications, verify specific standards required by your industry or regulatory body. The tool provides high precision suitable for most scientific and industrial applications, but always verify against authoritative standards for compliance-critical conversions.
Use grams/kilograms for scientific and metric-standard contexts. Use pounds/ounces for US customary measurements. Use troy ounces/pennyweights for precious metals. Use tons for large-scale logistics. Select units matching your industry standards, documentation requirements, and regional conventions. The converter supports all common unit systems, allowing flexibility for any application domain.
Grams are the SI (International System of Units) base unit for mass, providing a consistent foundation for all conversions. All weight conversions route through grams to ensure accuracy and consistency. This prevents errors from direct conversions between non-standard unit pairs and ensures all conversions follow the same precise calculation path regardless of source and target units.
Weight conversions are universal—they apply to all materials equally. One kilogram of water, one kilogram of gold, and one kilogram of feathers all weigh the same. However, volume-to-weight conversions (not provided by this tool) depend on material density. This converter handles pure mass/weight conversions that work identically for all substances regardless of material type.
Use exact conversion standards required by your regulatory body or industry. Verify conversions against authoritative references. For critical applications, maintain documentation of conversion methods. The tool uses precise international standards, but always cross-reference with authoritative sources for compliance-critical conversions. Export conversion history for audit trails if needed for regulatory documentation.