Convert weight and mass instantly — type a value, pick your units, and every other common unit updates live below. 100% free, runs entirely in your browser, no sign-up.
Every unit below updates live from the value you enter in the "From" field above.
Weight and mass are technically different things — mass is how much matter something has, weight is the force gravity exerts on it — but in everyday conversions (and on this page) they're used interchangeably, which is accurate enough for anything short of physics homework. The pound is legally defined as exactly 0.45359237 kilograms, which is the constant every imperial-to-metric conversion here is built on.
Yes. It's completely free with no sign-up, and every conversion runs locally in your browser via JavaScript — the numbers you type are never sent to our servers.
Each unit uses its standard, internationally defined conversion factor, calculated in full precision and only rounded for display. Results are accurate to at least 6 significant figures.
This page intentionally covers the most commonly used weight and mass units rather than an exhaustive engineering list. Use the suggestion button in the bottom-right corner of any page to request a unit and we'll consider adding it.
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