Weight Calculator
Convert between weight and mass units including pounds, kilograms, ounces, and grams.
A weight converter translates between common mass units including grams, kilograms, pounds, ounces, stone, and tons for everyday and scientific use.
Examples
Pounds to kilograms
Stone to pounds
Frequently Asked Questions
What is the difference between mass and weight?
What is the difference between a US ton and a metric tonne?
Quick Tips
- •Stone is commonly used in the UK and Ireland for body weight (1 stone = 14 pounds).
- •A US ton (short ton) = 2,000 lb. A metric tonne = 1,000 kg = 2,204.6 lb.
- •For cooking, 1 ounce = 28.35 grams.
A weight converter translates between common mass units including grams, kilograms, pounds, ounces, stone, and tons for everyday and scientific use.
How to Use This Calculator
Enter the weight value, select the source unit and target unit. The calculator converts between milligrams, grams, kilograms, ounces, pounds, stone, US tons, and metric tonnes.
Understanding the Formula
All conversions go through grams as the base unit. Result = Value x (FromUnit in grams) / (ToUnit in grams). Key factors: 1 kg = 2.20462 lb, 1 lb = 16 oz, 1 stone = 14 lb.
Examples
Pounds to kilograms
150 lb x 453.592 g/lb / 1000 g/kg = 68.039 kg.
Stone to pounds
12 stone x 14 lb/stone = 168 lb.
Frequently Asked Questions
What is the difference between mass and weight?
Mass is the amount of matter in an object (measured in kg), while weight is the force of gravity on that mass (measured in Newtons). On Earth's surface, they are proportional, so we use them interchangeably in everyday life.
What is the difference between a US ton and a metric tonne?
A US (short) ton is 2,000 pounds (907.185 kg). A metric tonne is 1,000 kg (2,204.62 lb). A UK (long) ton is 2,240 lb (1,016.05 kg).
Assumptions & Limitations
- All conversions use the gram as the intermediate base unit, so precision depends on the accuracy of each unit-to-gram factor.
- Stone is defined as exactly 14 pounds; regional variations in historical stone weights are not supported.
- US tons (short tons) are used by default; long (imperial) tons are not included.