About Weight Converter
Weight Converter moves a mass between seven units — milligrams, grams, kilograms, metric tons, ounces, pounds and stones. Supply the value, say which unit it is in, say which unit you want, and it returns the converted amount.
The metric units are exact powers of ten, so grams to kilograms and so on are simply a decimal shift. The imperial units use standard international values: an ounce is 28.3495 grams, a pound is 0.453592 kilograms and a stone is 6.35029 kilograms, the fourteen-pound unit still used for body weight in some countries.
One naming point is worth checking before you rely on a result. The unit labelled Tons here is the metric tonne of 1000 kilograms, not the US short ton of about 907 kilograms and not the UK long ton of about 1016 kilograms. If your source means either of those, the answer will be off by roughly ten percent — a difference that matters for freight, where the tonnage convention varies by country.
The seven units are fixed and the list cannot be extended. Troy weight — the system used for precious metals, where a troy ounce is about 31.1 grams — is not among the choices, nor are carats, grains, drams or any other specialty unit, so a jeweller's or apothecary measurement has to be converted outside the page. There is no way to enter a custom factor, no combined output that expresses the same mass as stones and pounds together the way body weight is conventionally written in some countries, and no scientific notation for very small or very large magnitudes. Only one conversion is produced at a time, so a mass needed in several units means running the tool repeatedly.
How to use Weight Converter
- 1 Enter the weight or mass to convert.
- 2 Choose the unit it is measured in on the From side.
- 3 Choose the target unit on the To side and run the conversion.
Frequently asked questions
Is the ton used here a metric tonne?
Yes. The Tons unit is the metric tonne of 1000 kilograms. The US short ton is about 907 kilograms and the UK long ton about 1016 kilograms, so if your figures are in either of those the result will be noticeably off.
How many pounds are in a stone?
Fourteen. The stone is a British unit still used informally for body weight, and it is exactly 6.35029 kilograms, which is fourteen pounds of 0.453592 kilograms each.
Are the ounce and pound the international versions?
Yes. The tool uses the international avoirdupois ounce and pound, the versions standardised in 1959 and used in most contexts today. Troy ounces, used for precious metals, are a different unit and not offered here.
Can it handle very large masses?
Within reason. Tons is the largest unit offered, so very large figures are expressed as a big number of tons. The underlying arithmetic uses floating-point numbers, so extreme values lose precision at the edges.
Free, online, and private
Free to use
Weight Converter is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Weight Converter behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Units covered | 7 — mg, g, kg, metric tons, oz, lb and stones |
| Conversion basis | kilogram, even though the tool is titled Weight Converter |
| Anchors | 1 t = 1,000 kg · 1 lb = 0.453592 kg · 1 oz = 0.0283495 kg · 1 st = 6.35029 kg |
| Arithmetic applied | (value × from-unit factor) ÷ to-unit factor |
| Result precision | 8 decimal places, from a starting Value of 1 |
| Default pair | kg → lb |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Weight Converter does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- The ton on this page is the metric tonne of 1,000 kg. A US short ton is 907.18474 kg, so a figure quoted in American tons reads about 10% heavier here, while a UK long ton at 1,016.0469088 kg reads slightly lighter — and the output gives no clue which ton was assumed.
- Ounces and stones are avoirdupois only. Troy ounces, pennyweights, grains and carats are absent from the list, so precious-metal weights cannot be handled here at all, and there is no compound stone-and-pounds readout for body weight either.
- The base unit is a kilogram but the interface calls the tool a weight converter, so a mass quoted in kgf or in pound-force has to be untangled by the reader first. Nothing in the output distinguishes mass from force, and no unit of weight-force appears in the list.
Tested and documented by itoolnet, the team that builds and maintains this site.