Convert length 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.
Length units fall into two families that don't share a common ancestor: the metric system (millimeters through kilometers, all powers of ten) and the imperial/US customary system (inches, feet, yards, miles), which trace back to old body-part and land-survey measurements. A meter is defined today by the distance light travels in a fraction of a second, while an inch is fixed by international agreement at exactly 25.4 millimeters — that's the constant this converter uses.
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 length 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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