Weight & Mass Converter
Convert between different units of weight and mass
All Conversions
How to Use This Weight Converter
- Enter the weight value you want to convert
- Select the unit you're converting from (kg, lb, oz, etc.)
- Select the unit you want to convert to
- Click 'Convert' to see the result and all equivalent values
Example: Converting 150 pounds to kilograms: 150 lb = 68.04 kg. The calculator also shows this equals 68,039 grams, 10.71 stone, or 0.075 US tons.
Tip: Use the swap button to quickly reverse your conversion direction without re-entering values.
Why Use a Weight Converter?
Weight conversions are needed constantly when cooking, shipping, traveling, or working with international specifications.
- Convert body weight between pounds and kilograms for medical records
- Scale recipes that use metric or imperial measurements
- Calculate shipping costs when carriers use different unit systems
- Understand product weights when shopping internationally
- Convert gym weights between pounds and kilograms
- Prepare luggage to meet airline weight limits in different countries
Understanding Your Results
Results show precise conversions with scientific notation available for very large or small values.
| Result | Meaning | Action |
|---|---|---|
| Micrograms to grams | Laboratory scale | Used for medications, supplements, chemical measurements |
| Grams to kilograms | Everyday metric | Common for cooking, body weight, shipping in most countries |
| Ounces to pounds | Everyday imperial | Standard in US for cooking, body weight, retail products |
| Stones | UK body weight | 1 stone = 14 lb; still used in UK and Ireland for personal weight |
Meaning: Laboratory scale
Action: Used for medications, supplements, chemical measurements
Meaning: Everyday metric
Action: Common for cooking, body weight, shipping in most countries
Meaning: Everyday imperial
Action: Standard in US for cooking, body weight, retail products
Meaning: UK body weight
Action: 1 stone = 14 lb; still used in UK and Ireland for personal weight
Note: Scientific applications typically use SI units (grams/kilograms), while US commerce uses imperial (pounds/ounces).
About Weight Converter
Formula
Target Value = Source Value × (Source Factor ÷ Target Factor) Each unit has a conversion factor relative to kilograms. To convert, multiply the source value by its factor (converting to kg), then divide by the target unit's factor.
Current Standards: The kilogram is defined by the Planck constant as of 2019, replacing the physical platinum-iridium prototype. The pound is legally defined as exactly 0.45359237 kilograms.
Frequently Asked Questions
What's the quick way to convert pounds to kilograms?
Divide pounds by 2.2 for a quick estimate. More precisely, multiply by 0.4536. For example, 150 lb ÷ 2.2 = 68.2 kg (actual: 68.04 kg). Going the other way, multiply kg by 2.2 to get pounds.
What's the difference between a US ton and a metric ton?
A US (short) ton equals 2,000 pounds (907 kg). A metric ton (tonne) equals 1,000 kilograms (2,205 lb). A UK (long) ton equals 2,240 pounds (1,016 kg). For rough estimates, metric and long tons are close, while short tons are about 10% smaller.
Why do some countries still use stones for body weight?
The stone (14 pounds) remains popular in the UK and Ireland for describing personal weight because the numbers are smaller and easier to remember. Saying '11 stone 4' is quicker than '158 pounds' and feels more natural to those raised with the system.
What are troy ounces and when are they used?
Troy ounces (31.1g) are used for precious metals like gold and silver, while avoirdupois ounces (28.35g) are used for everything else. This means a 'one-ounce' gold coin actually weighs more than a regular ounce. Always verify which ounce is being referenced when buying precious metals.
How do I convert cooking measurements accurately?
For dry ingredients: 1 oz = 28g, 1 lb = 454g. For precision baking, use a kitchen scale rather than volume measurements. Note that 'ounces' in recipes can mean fluid ounces (volume) or weight ounces—context matters. Flour, sugar, and butter have different densities.