Professional Weight Converter - Convert Between All Weight Units
Convert pounds, kilograms, ounces, grams, stones, and more with our precise weight converter. Perfect for cooking, shipping, fitness tracking, and scientific measurements. Get instant conversions with high precision calculations.
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70.0000 kg
11 st 0.3 lbs
Conversion Results
70.0000
154 lbs 5.2 oz
70000.0000
154.3236
2469.1773
11.0231
0.070000
Specialized Units
Weight Context
Visual Scale
Real-world Comparisons
Weight Categories
Professional Tips
- • Use metric units for scientific and medical applications
- • Always specify unit type when dealing with ounces (troy vs avoirdupois)
- • Calibrate scales regularly with certified reference weights
- • Allow temperature stabilization before critical measurements
- • Use appropriate precision for your application requirements
Last updated: November 4 2025
Curated by the QuickTooly Team
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Understanding Weight vs Mass: Complete Guide to Weight Measurements
Weight is the force exerted on an object due to gravity, measured in newtons in the SI system. However, in everyday usage, "weight" often refers to mass, measured in kilograms or pounds. Mass is the amount of matter in an object and remains constant regardless of location, while weight changes with gravitational force. Our weight converter handles both common usage and scientific applications.
This comprehensive weight converter supports metric (kilograms, grams, tonnes), imperial (pounds, ounces, stones), and specialized units (troy ounces, carats, grains) with precision up to 8 decimal places. Perfect for cooking, shipping, scientific research, jewelry, and international commerce where accurate weight conversions are essential.
Weight Measurement Systems & Conversion Factors
Metric System (SI Units)
The metric system uses grams as the base unit: 1 kilogram = 1,000 grams, 1 tonne = 1,000 kilograms = 1,000,000 grams. This decimal-based system makes calculations straightforward and is used worldwide for scientific, medical, and commercial applications. Prefixes like milli- (0.001), centi- (0.01), and kilo- (1,000) provide convenient scaling.
Imperial System
The imperial system uses pounds and ounces: 1 pound = 16 ounces, 1 stone = 14 pounds (primarily UK), 1 US ton = 2,000 pounds, 1 UK ton = 2,240 pounds. The pound is defined as exactly 453.59237 grams since the 1959 international agreement, ensuring consistent global conversions.
Specialized Units
Troy ounces (31.1035 g) for precious metals, carats (0.2 g) for gemstones, grains (0.0648 g) for pharmaceuticals and ammunition, and atomic mass units for scientific applications. Each serves specific industries with historical significance and continued relevance in professional contexts.
Professional Applications of Weight Conversions
- Cooking & Nutrition: Recipe scaling, portion control, and nutritional analysis require precise weight measurements. Professional kitchens use grams for accuracy, while home recipes often use cups or ounces. Converting between systems ensures consistent results across different measurement preferences.
- Shipping & Logistics: International shipping rates depend on accurate weight calculations. Freight companies use different weight breaks, and converting between metric and imperial systems prevents costly errors. Dimensional weight calculations also factor into shipping costs for lightweight, bulky items.
- Healthcare & Medicine: Dosage calculations, patient monitoring, and medical equipment calibration require precise weight measurements. Body weight tracking, medication dosing, and medical device specifications often need conversion between metric and imperial units for international standards.
- Manufacturing & Quality Control: Production specifications, material calculations, and quality control processes depend on accurate weight measurements. Raw material purchasing, inventory management, and product specifications often require conversions between supplier and customer preferred units.
- Precious Metals & Jewelry: Gold, silver, and gemstone trading uses troy ounces and carats. Investment portfolios, jewelry appraisals, and precious metal refining require accurate conversions between troy and avoirdupois systems, as well as metric equivalents for international markets.
Weighing Instruments & Measurement Accuracy
- Digital Scales: Modern digital scales provide readings from 0.1g to 0.001g precision depending on capacity and quality. Load cells convert weight to electrical signals, displayed digitally. Calibration with certified weights ensures accuracy, and environmental factors like temperature and vibration affect precision.
- Analytical Balances: Laboratory analytical balances measure to 0.0001g (0.1mg) accuracy for scientific applications. Enclosed chambers prevent air currents from affecting measurements, and internal calibration weights maintain accuracy. Essential for pharmaceutical, chemical, and research applications requiring extreme precision.
- Industrial Scales: Floor scales, crane scales, and truck scales handle weights from kilograms to tonnes with appropriate accuracy for their application. Load cells, strain gauges, and hydraulic systems provide measurement capabilities for heavy industrial applications and commercial trade.
- Calibration Standards: Certified reference weights ensure measurement traceability to national standards. NIST (US), NPL (UK), and other national metrology institutes maintain primary standards. Regular calibration prevents measurement drift and ensures regulatory compliance in commercial applications.
- Environmental Factors: Temperature, humidity, air pressure, and vibration affect weighing accuracy. Thermal expansion of materials, air buoyancy effects, and static electricity can introduce errors. Professional weighing requires controlled environments and proper measurement techniques.
Common Weight Measurement Mistakes & Solutions
- Unit Confusion: Mixing troy and avoirdupois ounces causes significant errors - troy ounces are about 10% heavier. Always specify the unit system when dealing with precious metals. Similarly, distinguish between US tons (2,000 lbs) and metric tonnes (2,204.6 lbs).
- Scale Overloading: Exceeding a scale's capacity damages the mechanism and affects accuracy permanently. Check maximum capacity before weighing, and use appropriate scales for the weight range. Overloading even once can permanently affect calibration.
- Tare Function Misuse: Forgetting to tare (zero) the scale with containers leads to incorrect net weights. Always tare between measurements, and verify zero reading without load. Accumulated tare values can compound errors in repetitive measurements.
- Temperature Effects: Weighing hot or cold items affects accuracy due to air convection and thermal expansion. Allow items to reach ambient temperature before weighing. Temperature differences can create air currents that affect sensitive measurements.
- Precision vs Accuracy: High precision (many decimal places) doesn't guarantee accuracy without proper calibration. A scale showing 100.0000g might be precisely wrong. Regular calibration with certified weights ensures both precision and accuracy for reliable measurements.
International Weight Standards & Regulations
Kilogram Redefinition (2019)
The kilogram is now defined by the Planck constant rather than a physical prototype, ensuring long-term stability and universal accessibility. This change maintains continuity while providing a fundamental constant-based definition that won't degrade over time like the previous physical standard.
Legal Metrology
Commercial transactions require legally compliant weighing equipment with proper certification and periodic verification. OIML (International Organization of Legal Metrology) standards ensure global harmonization of weighing requirements for trade, health, safety, and environmental protection.
Industry-Specific Standards
Aviation uses pounds for fuel and cargo calculations, shipping uses both metric and imperial depending on routes, and pharmaceuticals primarily use metric with grain subdivisions for traditional formulations. Understanding industry preferences prevents costly conversion errors.
Frequently Asked Questions About Weight Conversions
What's the difference between weight and mass?
Mass is the amount of matter in an object (measured in kg), while weight is the gravitational force on that mass (measured in newtons). In everyday usage, "weight" usually refers to mass. Your mass stays constant on Earth and the Moon, but your weight on the Moon is about 1/6 of Earth's due to lower gravity.
Why are there different types of ounces?
Avoirdupois ounces (28.35g) are used for general measurements, while troy ounces (31.10g) are used for precious metals. This historical distinction comes from different trading systems - troy weight for precious materials and avoirdupois for general commerce. Always specify which ounce system you're using.
How accurate do my weight measurements need to be?
Accuracy requirements depend on application: cooking typically needs ±1g, shipping requires ±0.1%, laboratory work needs ±0.01%, and precious metals require ±0.001%. Use the minimum precision necessary to avoid unnecessary costs while meeting quality requirements.
How do I convert recipes between metric and imperial?
For baking accuracy, weigh ingredients rather than using volume measurements. 1 cup flour ≈ 125g, 1 cup sugar ≈ 200g, but these vary by ingredient density and packing. Digital kitchen scales eliminate conversion errors and improve recipe consistency across measurement systems.
What affects weighing accuracy?
Temperature changes, air currents, vibration, static electricity, and magnetic fields can affect measurements. Use draft shields for sensitive measurements, allow temperature stabilization, eliminate vibration sources, and ensure proper grounding. Regular calibration with certified weights maintains long-term accuracy.
Professional Weight Measurement Tips & Best Practices
Master these professional techniques for accurate, reliable weight measurements in any application:
- Calibration Protocol: Establish regular calibration schedules using certified reference weights traceable to national standards. Document calibration results and maintain calibration certificates for regulatory compliance. Use multiple calibration points across the scale's range for comprehensive verification.
- Environmental Control: Minimize temperature fluctuations, air currents, and vibrations in weighing areas. Use anti-vibration tables for sensitive measurements, and allow thermal equilibration time. Install draft shields for analytical balances and maintain consistent humidity levels.
- Proper Technique: Center loads on the weighing platform, avoid overloading, and handle weights with forceps to prevent contamination. Use proper tare procedures and verify zero readings between measurements. Take multiple readings and average for critical measurements.
- Documentation Standards: Record measurement conditions, instrument identification, calibration status, and operator information. Maintain measurement logs for traceability and quality control. Include uncertainty estimates for critical measurements and specify measurement units clearly.