Converting between weight units
Converts weight (mass) between metric units (milligrams through metric tons) and imperial/US units (ounces, pounds, and stone). Useful for recipes, shipping weights, body weight tracking, and anywhere measurements need to move between the metric and imperial systems.
Why stone is included despite being unfamiliar to most of the world
The stone remains in everyday use specifically for reporting body weight in the United Kingdom and Ireland, even though both countries otherwise mostly use metric units - a holdover from before metrication that stuck around for this one particular use case, which is why it's included here even though it rarely appears outside that specific context.
Why shipping and recipe conversions both commonly need this tool
International shipping documentation often specifies weight limits in whatever unit the carrier's home country uses, while recipes written for different regional audiences default to whichever system is locally standard - both situations require converting a number you're given into the unit your own context actually uses, which is the core use case this tool is built around.
Why the metric and imperial systems need a fixed, defined conversion factor
The conversion between pounds and kilograms isn't an approximation Google settled on by convention - it's an internationally agreed, exactly defined figure (1 pound = 0.45359237 kg exactly), which is why this tool and any other properly built converter will always agree on the same result down to as many decimal places as you care to check.