📏 Length Converter
Convert any length measurement across imperial, metric, and space-scale units.
Select the starting and target units. The converter also shows quick comparisons to other common length units.
Enter a non-negative number.
1 Feet (ft) equals
0.3048 Meters (m)
Popular Conversions
Nanometers (nm)
304,800,000
Angstroms (Å)
3,048,000,000
Micrometers (µm)
304,800
Millimeters (mm)
305
Centimeters (cm)
30.48
Decimeters (dm)
3.048
Kilometers (km)
0.000305
Inches (in)
12
Feet (ft)
1
Yards (yd)
0.3333
Miles (mi)
0.000189
Nautical Miles (NM)
0.000165
Mils (thou)
12,000
Astronomical Units (AU)
0
Light Years (ly)
0
How to Use This Calculator
Enter the known length
Type the measurement you already have. Decimal values keep high precision.
Select the source and target units
Choose the units you are converting from and to. The calculator supports imperial, metric, and space units.
View detailed results
Scan the main conversion along with quick references to other units. Copy any value for use in plans or spreadsheets.
Formula
Converted Value = Input × (Conversion factor from source to meters) ÷ (Conversion factor from target to meters)
The converter uses meters as the base unit, ensuring consistency between imperial, metric, and astronomical scales.
Use the formula breakdown to confirm the calculation logic or perform the conversion manually if needed.
Full Description
Engineers, surveyors, astronomers, and DIYers routinely switch between length units. This converter removes the need for manual lookups by combining all major systems—imperial, metric, nautical, and astronomical—into a single interface.
Whether you are translating architectural drawings, converting sailing distances, or contextualising planetary scales, the tool keeps precision intact and surfaces multiple alternate units for quick reference.
The meter-based internal engine means chained conversions (for example, miles → kilometers → light years) remain accurate without accumulating rounding errors.
Frequently Asked Questions
Which units are supported?
Millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, nautical miles, astronomical units, and light years.
How accurate are the constants?
The calculator uses exact definitions where available (for example 1 in = 0.0254 m, 1 NM = 1852 m, 1 AU per IAU 2012) and high-precision values for light years.
Can I add custom units?
Not through the interface, but the underlying code is extensible. Add units to the `LENGTH_UNITS` map to extend the converter.
Does it handle enormous or tiny numbers?
Yes. The calculator uses JavaScript number precision, which comfortably covers typical engineering and astronomy ranges.