Length & Distance Converter

Quick Reference Table

From	To	Multiply By	Example
Meters	Feet	3.28084	10 m = 32.8 ft
Feet	Meters	0.3048	20 ft = 6.1 m
Inches	Centimeters	2.54	10 in = 25.4 cm
Centimeters	Inches	0.393701	100 cm = 39.4 in
Kilometers	Miles	0.621371	10 km = 6.2 mi
Miles	Kilometers	1.60934	5 mi = 8.05 km
Yards	Meters	0.9144	100 yd = 91.4 m
Millimeters	Inches	0.0393701	50 mm = 1.97 in

Common Length Measurements

Item	Imperial/US	Metric
Thickness of paper	~0.004 inches	~0.1 mm
Credit card thickness	0.03 inches	0.76 mm
Pencil length	7.5 inches	19 cm
Sheet of paper (letter)	8.5 × 11 inches	21.6 × 27.9 cm
Dollar bill length	6.14 inches	15.6 cm
Average human height (male)	5'9" (69 inches)	175 cm (1.75 m)
Average human height (female)	5'4" (64 inches)	162 cm (1.62 m)
Basketball hoop height	10 feet	3.05 meters
Football field length	100 yards	91.4 meters
Marathon distance	26.2 miles	42.195 km
Mount Everest height	29,032 feet	8,849 meters
New York to LA	~2,800 miles	~4,500 km

Understanding Length Units

Millimeter (mm)

Definition: One-thousandth of a meter (0.001 m). Equal to approximately 0.0394 inches. About the thickness of a credit card.

History: Part of the metric system developed in France in 1795. The prefix "milli-" means one-thousandth in Latin.

Current Use: Standard for small precise measurements worldwide. Used in engineering drawings, manufacturing specifications, rainfall measurements, screen dimensions (smartphone/TV bezels), screw and bolt sizes, and technical specifications. Wrench sizes in metric countries measured in mm. Rainfall measured in mm globally except US.

Centimeter (cm)

Definition: One-hundredth of a meter (0.01 m). Equal to 10 millimeters or approximately 0.394 inches.

History: Derived from the metric system. "Centi-" prefix means one-hundredth. Convenient for everyday measurements.

Current Use: Universal measurement in most countries for height, body measurements, small objects, and everyday items. Clothing sizes, screen sizes (diagonal), ruler markings, and height measurements outside US. Most people worldwide state their height in centimeters (175 cm vs 5'9").

Meter (m)

Definition: The SI base unit of length. Originally defined in 1793 as one ten-millionth of the distance from equator to North Pole. Since 1983, defined as the distance light travels in vacuum in 1/299,792,458 of a second.

History: Fundamental unit of the metric system, established in France during Revolution. Name from Greek "metron" meaning measure. Redefined multiple times for increasing precision.

Current Use: Universal standard for length measurements globally (except US, UK, Myanmar). Used for room dimensions, building measurements, athletic tracks, swimming pools, and all scientific work. 100-meter dash, buildings measured in meters, ceiling heights in meters (except US/UK).

Kilometer (km)

Definition: One thousand meters (1,000 m). Equal to approximately 0.621 miles or 3,281 feet.

History: Metric unit combining "kilo-" (thousand) with meter. Established with metric system for measuring longer distances.

Current Use: Standard distance unit worldwide for road signs, maps, geography, and travel. Speed limits and car speeds measured in km/h globally except US/UK. Running races (5K, 10K), cycling distances, flight distances internationally. Odometers show kilometers in most countries.

Inch (in or ")

Definition: Exactly 25.4 millimeters (defined in 1959). Equal to 1/12 of a foot. Traditionally based on width of human thumb.

History: Ancient unit with various historical definitions. Name from Latin "uncia" meaning one-twelfth. Standardized internationally in 1959 at exactly 25.4 mm.

Current Use: Primary small measurement in United States. Used for screen sizes (TV, phone, monitor diagonals), construction materials (2×4 lumber), body measurements, rainfall in US, screw/nail sizes, and tire widths. Still used in UK alongside metric. Ubiquitous in US manufacturing and construction.

Foot (ft or ')

Definition: Exactly 0.3048 meters or 12 inches (defined in 1959). Originally based on human foot length.

History: Ancient measurement unit varying historically. English foot standardized in 1266. International foot defined precisely in 1959. Name literally from human foot, though actual foot size varies.

Current Use: Dominant length unit in United States for height (5'9"), room dimensions, building measurements, altitude (aviation), and everyday distances. Still used in UK alongside meters. Real estate, construction plans, ceiling heights all in feet in US. Swimming pool depths, elevation signs in US.

Yard (yd)

Definition: Exactly 0.9144 meters or 3 feet (36 inches). Defined in 1959 international agreement.

History: Medieval English unit, allegedly based on distance from King Henry I's nose to outstretched thumb. Standardized over centuries. Name from Old English "gerd" meaning rod or stick.

Current Use: Used in United States for fabric (sold by yard), American football (100-yard field), gardening (mulch, topsoil sold by cubic yard), and some construction. Less common than feet for most applications. Golf course distances in yards. Gradually declining in use.

Mile (mi)

Definition: Statute mile equals exactly 1.609344 kilometers or 5,280 feet. Different from nautical mile (1.852 km).

History: From Latin "mille passus" meaning thousand paces. Roman mile was 1,000 paces. English statute mile standardized at 5,280 feet in 1593. International mile defined precisely in 1959.

Current Use: Primary long-distance unit in United States and UK. Used for road signs, speed limits (mph), vehicle odometers, running races (mile time), and geography in US/UK. Speed limits 25-70 mph in US. "Four-minute mile" athletic benchmark. Nautical mile (1.852 km) used in aviation and maritime navigation worldwide.

Nautical Mile (nmi)

Definition: Exactly 1,852 meters or approximately 1.151 statute miles. Equal to one minute of latitude on Earth's surface.

History: Based on Earth's geometry - one minute of arc along a meridian. Standardized internationally in 1929 for navigation.

Current Use: Universal standard in maritime and aviation navigation worldwide, regardless of country's measurement system. Ship speeds in knots (nautical miles per hour), aircraft distances, maritime boundaries, and navigation charts. Used because it relates directly to latitude/longitude.

Light-Year (ly)

Definition: Distance light travels in one year in vacuum: approximately 9.461 trillion kilometers or 5.879 trillion miles.

History: Astronomical distance unit emerged in 1800s as scientists measured stellar distances. Convenient for interstellar scales.

Current Use: Astronomy and astrophysics for measuring distances to stars and galaxies. Nearest star (Proxima Centauri) is 4.24 light-years away. Milky Way galaxy is ~100,000 light-years across. Not used for everyday measurements.

Micrometer (μm or micron)

Definition: One-millionth of a meter (0.000001 m) or one-thousandth of a millimeter. Microscopic scale.

History: Metric prefix "micro-" from Greek meaning small. Important for microscopy and precision manufacturing.

Current Use: Biology (cell sizes: 10-100 μm), semiconductor manufacturing (chip feature sizes now in nanometers), filtration (filter pore sizes), and precision engineering. Human hair diameter: ~70 μm. Red blood cell: ~7 μm.

Frequently Asked Questions

How many feet are in a meter?

One meter equals 3.28084 feet (approximately 3.28 feet). To convert meters to feet, multiply by 3.28084. Example: 10 meters × 3.28084 = 32.8 feet. To convert feet to meters, multiply by 0.3048. Quick estimate: 1 meter ≈ 3.3 feet, or roughly 10 feet = 3 meters.

How many centimeters in an inch?

One inch equals exactly 2.54 centimeters (defined precisely in 1959). To convert inches to cm, multiply by 2.54. Example: 10 inches × 2.54 = 25.4 cm. To convert cm to inches, divide by 2.54 or multiply by 0.3937. This is one of the most important conversion factors for international measurements.

How do I convert my height to centimeters?

If you're 5'9": Convert feet to inches (5 × 12 = 60), add remaining inches (60 + 9 = 69), multiply by 2.54 (69 × 2.54 = 175.26 cm). Quick formula: (feet × 30.48) + (inches × 2.54) = centimeters. Most people round to nearest cm (175 cm for 5'9").

How many kilometers in a mile?

One mile equals 1.609344 kilometers (exact). To convert miles to km, multiply by 1.609 (or 1.6 for quick estimates). Example: 5 miles × 1.609 = 8.05 km. To convert km to miles, multiply by 0.621. Quick rule: 5 miles ≈ 8 km, 100 km ≈ 62 miles.

How tall is 6 feet in meters?

6 feet equals 1.83 meters (approximately). Calculation: 6 × 0.3048 = 1.8288 m, usually rounded to 1.83 m. Common heights: 5'0" = 1.52 m, 5'6" = 1.68 m, 5'9" = 1.75 m, 6'0" = 1.83 m, 6'3" = 1.91 m.

What is 180 cm in feet and inches?

180 cm equals approximately 5 feet 11 inches. Calculation: 180 ÷ 2.54 = 70.87 inches. Divide by 12: 70.87 ÷ 12 = 5.91 feet = 5 feet + (0.91 × 12) = 5 feet 10.9 inches, rounded to 5'11". Quick reference: 170 cm ≈ 5'7", 175 cm ≈ 5'9", 180 cm ≈ 5'11", 185 cm ≈ 6'1".

Why are there 5,280 feet in a mile?

Historical quirk. Roman mile was 1,000 paces (about 5,000 feet). In 1593, Queen Elizabeth I standardized the mile at 8 furlongs (660 feet each) = 5,280 feet to match agricultural land measurements (furlong = "furrow-long"). This odd number persists today in US/UK despite metric simplicity (1 km = 1,000 m).

How do I measure without a ruler?

Approximate measurements: Adult thumb width ≈ 1 inch (2.5 cm). Hand span (thumb to pinky stretched) ≈ 9 inches (23 cm). Forearm (elbow to fingertips) ≈ 18 inches (45 cm). Foot length ≈ 12 inches for many adults. Dollar bill ≈ 6 inches long. Credit card ≈ 3.4 inches (8.6 cm) wide. Measure and remember your own body measurements for estimates.

Common Uses for Length Conversion

• International Travel: Understanding distances and road signs abroad
• Online Shopping: Converting clothing sizes and product dimensions
• Construction & DIY: Following plans in different measurement systems
• Height & Body Measurements: Medical records, dating profiles, athletics
• Sports & Fitness: Converting running distances (5K = 3.1 miles)
• Real Estate: Understanding property dimensions internationally
• Science & Education: Lab work and homework requiring conversions
• Shipping & Packaging: Meeting international size requirements

Length Conversion Tips

1. Key conversions: 1 in = 2.54 cm (exact), 1 ft ≈ 30 cm, 1 m ≈ 3.3 ft, 1 mi ≈ 1.6 km
2. Quick foot to meter: Divide by 3 (approximate: 6 ft ≈ 2 m)
3. Quick mile to km: Multiply by 1.6 or use 5 mi = 8 km rule
4. Height conversion: Feet × 30.48 + inches × 2.54 = cm
5. Remember 2.54: Inch to cm conversion is exact, memorize it
6. Use proper notation: Feet ('), inches ("), or ft/in to avoid confusion
7. Body reference: Measure your hand span, foot, forearm for quick estimates

Interesting Length Facts

• Planck length: 1.616 × 10⁻³⁵ m (smallest meaningful length in physics)
• Hydrogen atom diameter: 0.1 nanometers (nm)
• Human hair width: ~70 micrometers (0.07 mm)
• Tallest person ever: Robert Wadlow, 8'11" (2.72 m)
• Great Wall of China: ~21,000 km (13,000 mi) including branches
• Earth's circumference: 40,075 km (24,901 mi) at equator
• Distance to Moon: ~384,400 km (238,855 mi) average
• Distance to Sun: ~150 million km (93 million mi)
• Light travels: 299,792 km per second (186,282 mi/s)
• Deepest ocean trench: Mariana Trench, 10,994 m (36,070 ft)
• Tallest building: Burj Khalifa, 828 m (2,717 ft)
• Golden Gate Bridge span: 1,280 m (4,200 ft)
• Eiffel Tower: 330 m (1,083 ft) with antenna
• Football field: 100 yards (91.4 m) between goal lines
• Standard door height: 80 inches (203 cm) in US
• Human step length: ~30 inches (76 cm) average

Length in Different Contexts

Human Height Ranges

Average adult male (global): 5'7"-5'10" (170-178 cm). Average adult female (global): 5'2"-5'5" (158-165 cm). US average male: 5'9" (175 cm). US average female: 5'4" (163 cm). Netherlands (tallest): male 6'0" (183 cm), female 5'7" (171 cm).

Athletics & Sports

100-meter dash: 328 feet. Marathon: 26.2 miles (42.195 km exactly). 5K race: 3.107 miles. 10K race: 6.214 miles. Olympic pool: 50 meters (164 feet). Basketball court: 94 × 50 feet (28.7 × 15.2 m). Tennis court: 78 × 36 feet (23.8 × 11 m). Soccer field: 100-110 m long (110-120 yards).

Construction Standards

Standard ceiling height (US): 8 feet (2.44 m) residential. Doorway width: 32-36 inches (81-91 cm). Stair step height: 7-7.75 inches (18-19.7 cm). Kitchen counter: 36 inches (91 cm) height. Plywood sheet: 4×8 feet (1.22×2.44 m). 2×4 lumber: actually 1.5×3.5 inches (3.8×8.9 cm).

Geographic Distances

New York to LA: 2,800 miles (4,500 km). London to Paris: 214 miles (344 km). Tokyo to Osaka: 250 miles (400 km). Across English Channel (narrowest): 21 miles (34 km). Panama Canal: 51 miles (82 km). Suez Canal: 120 miles (193 km).

Altitude References

Sea level: 0 m. Denver (Mile High City): 5,280 feet (1,609 m). Commercial jet cruise: 35,000-40,000 feet (10,700-12,200 m). Mount Everest: 29,032 feet (8,849 m). Kármán line (space boundary): 100 km (62 miles, 328,000 feet).

Measurement System Comparison

Countries Using Metric System

Nearly all countries worldwide use metric (meters, kilometers) as official system: all of Europe, Asia (except Myanmar), Africa, South America, Australia, Canada (officially metric, some imperial use persists).

Countries Using Imperial/US Customary

United States: primary use of feet, inches, miles. Liberia and Myanmar also officially use imperial units. United Kingdom: officially metric but imperial still widely used (miles on road signs, feet/inches for height, pints for beer).

Why US Hasn't Adopted Metric

Cost of conversion (trillions to replace infrastructure, signs, tools). Cultural attachment to traditional units. Metric officially legal in US since 1866. Gradual adoption in science, medicine, military. Public resistance to change. Existing investment in imperial tools and equipment makes full conversion economically challenging.