Length Converter

Convert between 18 length units instantly — from nanometers to light-years.

Conversion table

Length	Meters	Feet	Inches
0.5	0.5000 m	1.64 ft	19.685 in
1	1 m	3.281 ft	39.37 in
1.5	1.5 m	4.921 ft	59.055 in
2	2 m	6.562 ft	78.74 in
2.5	2.5 m	8.202 ft	98.425 in
3	3 m	9.843 ft	118.11 in
4	4 m	13.123 ft	157.48 in
5	5 m	16.404 ft	196.85 in
6	6 m	19.685 ft	236.22 in
7	7 m	22.966 ft	275.591 in
8	8 m	26.247 ft	314.961 in
9	9 m	29.528 ft	354.331 in
10	10 m	32.808 ft	393.701 in
12	12 m	39.37 ft	472.441 in
15	15 m	49.213 ft	590.551 in

💡 Quick References

1 inch = 2.54 cm exactly (defined by international agreement since 1959).
1 mile = 1.60934 km — multiply miles by 1.6 for a quick estimate.
1 meter ≈ 3 feet 3 inches — slightly longer than a yard (3 feet).
1 foot = 12 inches = 30.48 cm — the most common US measurement unit.

Understanding Length Units

Length measurement systems evolved independently across civilizations. Today, two major systems dominate: the metric system (meters, centimeters, kilometers) used by most of the world, and the imperial/US customary system (feet, inches, miles) used primarily in the United States, Liberia, and Myanmar. The metric system is based on powers of 10, making conversions straightforward (1 km = 1,000 m = 100,000 cm). The imperial system has irregular relationships (1 mile = 5,280 feet = 63,360 inches). The international inch was defined as exactly 25.4 millimeters in 1959, creating a precise bridge between the two systems.

How Length Conversion Works

All length conversions work through a base unit — in this converter, the meter. To convert from any unit to any other, we first convert to meters using the known conversion factor, then convert from meters to the target unit. For example, to convert 5 feet to centimeters: 5 ft × 0.3048 m/ft = 1.524 m, then 1.524 m × 100 cm/m = 152.4 cm. This two-step process through a base unit ensures accuracy and allows conversion between any pair of units without needing a direct conversion factor for every possible pair.

Common Length Equivalences

1 inch = 25.4 mm = 2.54 cm (exact by international definition)
1 foot = 12 inches = 30.48 cm = 0.3048 m (exact)
1 yard = 3 feet = 36 inches = 0.9144 m (exact)
1 mile = 5,280 feet = 1,760 yards = 1.60934 km
1 kilometer = 1,000 m = 0.621371 miles ≈ 5/8 of a mile
1 nautical mile = 1,852 m = 1.15078 statute miles (used in navigation)

Special Length Units

Nanometer (nm): 1 billionth of a meter — used for wavelengths of light and semiconductor chips
Micrometer (µm): 1 millionth of a meter — used for bacteria, cell sizes, and thin film measurements
Fathom: 6 feet — traditionally used for measuring water depth in maritime navigation
Furlong: 660 feet (1/8 mile) — still used in horse racing distances
Astronomical Unit (AU): ~150 million km — the distance from Earth to the Sun
Light-year: ~9.46 trillion km — the distance light travels in one year

Length Conversion Examples

Step-by-step conversions

Height: 5'10" to cm

5 feet = 5 × 30.48 = 152.4 cm
10 inches = 10 × 2.54 = 25.4 cm
Total = 152.4 + 25.4 = 177.8 cm
Or: 70 inches × 2.54 = 177.8 cm
Verify: 177.8 / 30.48 = 5.833 ft = 5'10"

5 feet 10 inches = 177.8 cm

Marathon: 26.2 miles to km

1 mile = 1.60934 km
26.2 × 1.60934 = 42.165 km
Standard marathon = 42.195 km (exact)
Half marathon = 21.0975 km = 13.1 mi
Quick estimate: miles × 1.6 ≈ km

26.2 miles ≈ 42.16 km

Frequently Asked Questions

How many centimeters are in an inch?

There are exactly 2.54 centimeters in one inch. This is an exact definition established by international agreement in 1959. To convert inches to centimeters, multiply by 2.54. To convert centimeters to inches, divide by 2.54 (or multiply by 0.3937).

How do I convert meters to feet?

Multiply meters by 3.28084 to get feet. For example, 1.8 meters × 3.28084 = 5.905 feet ≈ 5 feet 10.9 inches. For a quick estimate, multiply meters by 3.3. To convert feet to meters, multiply by 0.3048.

How many kilometers are in a mile?

One mile equals 1.60934 kilometers. For quick mental math, multiply miles by 1.6 (or by 8 and divide by 5). One kilometer equals 0.621371 miles, or roughly 5/8 of a mile.

What is the difference between metric and imperial systems?

The metric system is based on powers of 10 (1 km = 1,000 m = 1,000,000 mm), making conversions simple. The imperial system uses irregular ratios (1 mile = 5,280 feet, 1 foot = 12 inches). The metric system is used by most of the world; imperial is primarily used in the US, Liberia, and Myanmar.

How do I convert between feet and inches?

1 foot = 12 inches. To convert feet to inches, multiply by 12. To convert inches to feet, divide by 12. For mixed measurements like 5'10", convert: (5 × 12) + 10 = 70 total inches. To go back: 70 ÷ 12 = 5 remainder 10, so 5 feet 10 inches.

What is a nautical mile?

A nautical mile equals 1,852 meters (1.15078 statute miles or 6,076 feet). It was originally defined as one minute of arc of latitude along the Earth's surface, making it particularly useful for navigation. Nautical miles are used in maritime and aviation for measuring distances, and speed in knots is nautical miles per hour.