What is a weight converter?
A weight converter changes a measurement from one weight unit to another. It is useful when a food label, package, fitness plan, recipe, shipping form or product specification uses a unit that is unfamiliar. Enter the value you have, select its current unit and choose the unit you need to see the equivalent result immediately.
This tool covers common metric units including milligrams, grams, kilograms and metric tonnes, as well as ounces, pounds and stones. It works locally in your browser, so the value you enter is never uploaded or stored. You can enter whole numbers or decimals for more precise conversions.
How to use this weight converter
- Type the weight you want to convert into the value field.
- Choose the unit you are starting with in the From menu.
- Choose the target unit in the To menu.
- Read the converted value and the full equivalence statement.
- Use Swap units to reverse the conversion direction quickly.
For example, enter 5, select kilograms as the starting unit and pounds as the target unit to see the equivalent weight in pounds. To turn pounds into kilograms, swap the units or choose pounds in From and kilograms in To. Negative values are accepted for mathematical conversions, although ordinary physical weights are usually positive.
How weight conversions work
Each supported unit has a fixed relationship to the gram, which the calculator uses as its common base. It first changes the entered amount into grams, then divides by the number of grams in the target unit. This two-step approach gives consistent results for every supported pair without relying on separate formulas for each conversion.
Useful reference values include 1,000 milligrams in a gram, 1,000 grams in a kilogram and 1,000 kilograms in a metric tonne. One pound equals exactly 453.59237 grams, while one ounce equals one sixteenth of a pound. A stone is 14 pounds. The converter retains useful precision, but you may want to round the displayed result to match the purpose of your measurement.
Why use an online weight converter?
Manual conversions are easy to misplace when moving between metric and imperial units, especially with decimal values. A converter avoids that arithmetic and makes it simpler to compare product weights, follow a recipe or report a measurement in the unit requested. This tool gives a clear conversion result, but it does not replace a calibrated scale or account for measurement uncertainty. For scientific, medical or regulated work, follow the rounding and accuracy rules required for that task.