Convert between kg, lb, oz, grams, stones, tons, carats, troy ounces and more instantly
Mass Converter is a free online tool that converts between different units of mass and weight. It supports metric units (kg, g, mg), imperial units (lb, oz, stones), troy units (troy ounces, grains), precious metal units (carats), and atomic units. Perfect for cooking, science, jewelry, and everyday weight conversions.
All conversions use standard conversion factors and are accurate to 6 decimal places. For most practical purposes, this provides excellent precision.
Mass is the amount of matter in an object (constant everywhere), while weight is the force of gravity on that mass. This converter handles mass units, though some are commonly called "weight" units.
Troy ounces are used for precious metals and are slightly heavier than regular ounces. US tons (short tons) and UK tons (long tons) have different weights due to historical measurement systems.
Yes, all calculations happen locally in your browser. Your data never leaves your device.
Yes, once loaded, the converter works completely offline in your browser.