Meters and feet: the metric and imperial gap
Where the meter and the foot come from, why the 0.3048 factor is exact, and how to move between metric and imperial lengths with confidence.
Two systems, one length
A meter and a foot both measure the same thing, distance, but they belong to rival measurement systems. The meter is the base length unit of the metric system, now the SI standard used by most of the world and all of science. The foot is an imperial and US customary unit, still dominant for height, construction and everyday distances in the United States. Because both describe real length, any measurement in one can be stated exactly in the other, which is what this converter does.
Why the factor is exactly 0.3048
Since 1959 the international foot has been defined as exactly 0.3048 meters by international agreement, replacing the slightly varying national feet that came before. That single clean definition is why the conversion has no rounding error at its root: feet is simply meters divided by 0.3048. Multiplying instead by 3.28084 gives the same answer to five decimals, which is where the familiar rule of thumb comes from. Knowing the factor is exact means you can trust the result even for long distances.
Estimating in your head
For quick mental math, a meter is a bit more than three and a quarter feet, so tripling the meters and adding a little gets you close. A doorway around two meters tall is roughly six and a half feet, and a 100 meter track is a shade over 328 feet. When you need the precise number, though, small errors add up over distance, so it is worth using the exact figure rather than rounding to three feet per meter.
Where each unit shows up
You will meet meters on running tracks, swimming pools, maps and product specs almost everywhere outside the United States. Feet dominate US real estate, aviation altitude worldwide, and the height of people and buildings in imperial countries. Mixing the two is a classic source of mistakes, and one famous spacecraft was lost to a unit mismatch, so converting carefully rather than guessing is more than a nicety.