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Convert between metric and imperial length units instantly.
📏 Supports metric (mm, cm, m, km) and imperial (in, ft, yd, mi) units.
The world uses two main measurement systems for length. The metric system (millimeters, centimeters, meters, kilometers) is used by nearly every country and is based on powers of 10, making conversions simple. The imperial system (inches, feet, yards, miles) is used primarily in the United States and has more irregular relationships between units.
The most-used length conversions, with exact values:
Everyday conversions worth memorizing:
The US adopted the imperial system before metric became the global standard, and switching would be enormously expensive — every road sign, recipe, and manufacturing spec would need to change. The UK uses a hybrid: distances in miles, fuel in liters, beer in pints. Canada is officially metric but still uses imperial for many everyday measurements due to US cultural influence.
The Length Converter converts length converterfrom one unit to another using the exact internationally defined conversion factors. Type a value, choose your source and target units, and the converted result is shown instantly — no waiting, no page reload.
Manual conversion is error-prone because it means memorizing ratios (how many feet in a meter, how many pints in a liter). This tool removes that friction: the conversion factor is built in, and the math is done to full precision with no rounding until the final displayed number.
Common uses: people reach for this tool when they need to look up a meters to feet converter, centimeters to inches converter, cm to inches conversion, or miles to kilometers converter.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
The Length Converter is based on the following formula:
1 in = 25.4 mm (exact) 1 ft = 12 in = 0.3048 m 1 yd = 3 ft = 0.9144 m 1 mi = 5280 ft = 1609.344 m 1 nmi = 1852 m 1 km = 1000 m
Variables: mm = millimeters cm = centimeters m = meters km = kilometers in = inches ft = feet yd = yards mi = statute miles nmi = nautical miles
The 1959 international yard and pound agreement defines the inch as exactly 25.4 mm, which makes the foot (0.3048 m) and mile (1609.344 m) conversions exact rather than rounded measurements. The nautical mile is 1 minute of latitude, fixed at 1852 m.
Worked example: Convert a 6 ft person to metric: m = 6 × 0.3048 = 1.8288 m ≈ 183 cm Convert 5 km to miles: mi = 5000 ÷ 1609.344 ≈ 3.11 mi Reverse: a 26.2 mi marathon = 26.2 × 1609.344 ≈ 42.16 km
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