Weight Converter
How it works
Seven units in every direction is forty-two pairwise formulas, so this converter does not write forty-two. Every value is turned into grams first and back out again: multiply by the entered unit's grams-per-unit, then divide by the target unit's. Milligrams, grams, kilograms and tonnes are exact powers of ten apart; ounces, pounds and stone use the defined avoirdupois figures, with 1 lb fixed at exactly 453.59237 g and 1 stone at exactly 14 lb. Going through one basis means all seven answers on the page agree with each other by construction, not by coincidence.
Nothing here is rejected for being negative or zero. A mass has no absolute floor the way a temperature does — zero is a real weight (an empty container) and a negative number is a legitimate delta, such as a change on a scale from one week to the next.
Frequently asked questions
Why does 1 stone equal exactly 14 pounds?
Because that is the definition, not a measurement. A stone is fixed by convention as 14 avoirdupois pounds, so the relationship is exact rather than a rounded-off approximation — unlike, say, kilograms to pounds, which is a genuinely irrational-looking decimal.
Is a US ton the same as a metric tonne?
No. This converter’s "t" is the metric tonne — 1,000 kg. A US short ton is a different, larger-in-name unit built from 2,000 avoirdupois pounds (about 907.18 kg), and it is not one of the seven units here — mixing it in under the same letter is exactly the kind of silent wrong answer this tool is built to avoid.
How precise are these conversions?
Exact, definitional factors for all seven units — milligrams, grams, kilograms and tonnes are exact metric multiples, and ounces, pounds and stone use the defined avoirdupois figures (1 lb = 453.59237 g exactly), not rounded-for-convenience ones. Nothing here is a rule-of-thumb approximation.