Weight Conversion Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/5/2026
To convert a weight, it's brought to a common unit (the kilogram) and then converted into the new unit. For example, 150 pounds is about 68.04 kg.
Explanation
The kilogram is the mass unit of the metric system, used across most of the world. The pound ("lb") and the ounce ("oz") belong to the imperial/US system still used in the United States, notably for body weight or American recipes. One pound equals exactly 0.45359237 kg and splits into 16 ounces, giving an ounce a value of about 28.35 grams. This calculator converts both ways between the five most common units (kilogram, gram, tonne, pound, ounce) by going through the kilogram as a pivot unit. For a length conversion, see our length conversion calculator; for a volume, our volume conversion calculator.
Example: converting 150 pounds to kilograms
Inputs
Value: 150. Starting unit: pounds. Target unit: kilograms.
Calculation
150 pounds × 0.45359237 kg per pound = 68.0388555 kg.
Result
150 pounds is about 68.04 kg.
Frequently asked questions
What's the difference between a tonne and a pound?
They're two opposite orders of magnitude: a metric tonne equals 1,000 kg, while a pound equals about 0.45 kg. The tonne is used for large masses (vehicles, construction materials), the pound for masses closer to everyday life (body weight, food).
Why is body weight often given in pounds in the United States?
The United States never officially adopted the metric system for everyday use, unlike almost the entire rest of the world. The pound therefore remains the reference unit for body weight, recipes, and many everyday American uses.
Does this calculator distinguish the avoirdupois pound and ounce from other historical definitions?
This calculator uses the avoirdupois pound and ounce, the modern and most common definitions, used for body weight and commercial purposes. Other historical definitions (the troy ounce, notably for precious metals) exist but aren't covered here.