Length Converter

From the width of a human hair (0.07 mm) to the distance between galaxies, length is the most fundamental measurement in human history. Whether you need feet to meters for a building plan, miles to kilometers for a road trip, or inches to centimeters for a clothes order from abroad — get the exact number here.

All Converters

Quick Reference: Most Searched Length Conversions

5'11" in cmHeight
180.3 cm
6 feet in metersHeight
1.83 m
1 mile in kmDistance
1.609 km
5 km in miles5K race
3.107 mi
Marathon in milesRunning
26.22 mi
100 meters in feetSprint
328.1 ft
1 inch in mmExact
25.4 mm
10 cm in inchesShopping
3.937 in

Real-World Length Scale

How these numbers relate to everyday life
0.1mm
Human hair
Average hair thickness: 0.06–0.10 mm
1cm
Pinky fingernail
Width of an adult little finger
30.48cm
One foot
Exact length — used in US construction daily
1m
Kitchen counter height
Standard worktop height in most countries
1.75m
Average adult height
Global average: 1.72 m (men), 1.60 m (women)
100m
Football field length
FIFA standard: 100–110 m
1km
12 min walk
Average walking speed: ~5 km/h
8.85km
Mount Everest
Highest point on Earth: 8,849 m above sea level
384,400km
Earth to Moon
Average distance — light covers it in 1.3 seconds

Who Uses Length Conversions?

Construction

US blueprints use feet and inches; European plans use meters and centimeters. Mixed projects require constant conversion.

Standard interior door: 6'8" (203 cm) tall × 32"–36" (81–91 cm) wide

Medicine

Height in patient records is in cm almost everywhere except the US, which uses feet/inches. BMI calculations require meters.

BMI formula: weight(kg) ÷ height(m)² — a 5'9" (175 cm) person needs the cm value

Running & Fitness

Race distances are metric globally (5K, 10K, half marathon, marathon). US road races still use miles for casual events.

5K = 3.107 mi | 10K = 6.214 mi | Half marathon = 13.1 mi = 21.097 km

Aviation

Aircraft altitude is measured in feet internationally (ICAO standard), but runway lengths vary — many countries use meters.

Typical cruising altitude: 35,000 ft = 10,668 m. Runway length: ~3,000–4,500 m

Textile & Fashion

Clothing sizes differ by country. European sizing uses cm for body measurements; US uses inches.

EU size 38 dress ≈ US size 8. Waist: 71 cm = 28 inches

Length Conversion Formulas

Metric → Imperial

  • Meters to feet× 3.28084
  • Centimeters to inches÷ 2.54
  • Kilometers to miles× 0.621371
  • Millimeters to inches÷ 25.4

Imperial → Metric

  • Feet to meters× 0.3048
  • Inches to centimeters× 2.54
  • Miles to kilometers× 1.60934
  • Yards to meters× 0.9144
All factors from NIST official definitions. The inch and foot have been exact since the 1959 International Yard and Pound Agreement.

Did You Know?

The meter was originally defined in 1793 as exactly 1/10,000,000 of the distance from the equator to the North Pole through Paris — making Earth's circumference almost exactly 40,000 km.

Source: BIPM

The foot varies historically from 25 cm (Roman foot) to 34 cm depending on culture and era. The current international foot (0.3048 m) was standardized only in 1959.

Source: NIST

A nautical mile (1.852 km) equals exactly one minute of arc of latitude on Earth's surface — so 60 nautical miles = 1 degree of latitude.

Source: IHO

Common Mistakes to Avoid

Writing height as "5.9 feet" instead of 5 feet 9 inches

Convert properly: 5 ft 9 in = (5 × 12) + 9 = 69 inches = 175.26 cm

Confusing meters and yards (they look similar but differ by ~9%)

1 yard = 0.9144 m. A 100-yard football field is only 91.4 meters — not 100.

Using "1 km = 1000 m" to eyeball miles, getting a 60% error

Remember: 1 mile ≈ 1.6 km. Or: 5 miles ≈ 8 km (easy mental math).

Related Converters

Area
Square feet, m², acres
Speed
mph, km/h, knots
Volume
Liters, gallons, cups
Weight
kg, lbs, oz, grams

Length Conversion FAQ