Length & Distance Converters — All 44 Conversions

By EnginStack Editorial Team | Reviewed against NIST, BIPM and primary-source documentation About →

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Metric vs imperial history, the 1959 treaty, the Mars Climate Orbiter, the Gimli Glider, and systematic pitfalls across 5 engineering disciplines. 30 linked converters, exact constants, failure cases.

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Inches

Inches to Centimeters 1 in = 2.54 cm. The conversion behind every global supply chain tolerance sheet. TV screens, furniture, PCB design. × 2.54 Centimeters to Inches 1 cm ≈ 0.3937 in. Metric product dimensions read as imperial. Common in apparel and packaging. ÷ 2.54 Inches to Millimeters 1 in = 25.4 mm. The machinist's constant. Every CNC program and tolerance callout uses this. × 25.4 Millimeters to Inches 1 mm ≈ 0.03937 in. Bolt sizes, sheet metal gauges, bearing bores — metric parts in imperial shops. ÷ 25.4 Inches to Feet 12 in = 1 ft. Construction framing, lumber lengths, human height. The US standard since before the revolution. ÷ 12 Feet to Inches 1 ft = 12 in. Converting architectural dimensions to shop drawings. Every US tape measure. × 12 Inches to Yards 36 in = 1 yd. Fabric, carpet, and football fields. Mostly retail and textile applications. ÷ 36 Yards to Inches 1 yd = 36 in. Textile manufacturing, sewing patterns, material takeoffs. × 36

Feet

Feet to Meters 1 ft = 0.3048 m. The bridge between US construction and international engineering. BIM, structural steel, aviation. × 0.3048 Meters to Feet 1 m ≈ 3.28084 ft. International building code translation. Metric blueprints for US contractors. ÷ 0.3048 Feet to Centimeters 1 ft = 30.48 cm. Human height for medical records. Every doctor's office outside the US. × 30.48 Centimeters to Feet 1 cm ≈ 0.03281 ft. Converting metric body measurements to imperial. Fitness, health, apparel. ÷ 30.48 Feet to Millimeters 1 ft = 304.8 mm. Precision manufacturing from architectural drawings. Steel detailing and fabrication. × 304.8 Millimeters to Feet 1 mm ≈ 0.003281 ft. Metric shop drawings into imperial framing dimensions. ÷ 304.8 Feet to Yards 3 ft = 1 yd. Concrete pours, landscaping, sports field dimensions. Every US contractor knows this cold. ÷ 3 Yards to Feet 1 yd = 3 ft. Excavation volumes, turf orders, pipeline trenching. The cubic yard starts here. × 3 Feet to Miles 5,280 ft = 1 mi. Land surveying, property lines, civil engineering. The Roman mille passus lives on. ÷ 5,280 Miles to Feet 1 mi = 5,280 ft. A mile is 5,280 feet because 8 furlongs × 660 feet — blame the 16th century. × 5,280

Meters & Centimeters

Meters to Centimeters 1 m = 100 cm. The base SI length unit divided into hundredths. Every metric tape measure. × 100 Centimeters to Meters 100 cm = 1 m. Converting smaller measurements into the SI base unit for calculations. ÷ 100 Meters to Millimeters 1 m = 1,000 mm. Engineering drawings always dimension in mm — avoids decimal points entirely. × 1,000 Millimeters to Meters 1,000 mm = 1 m. Converting shop dimensions back to SI base for structural analysis. ÷ 1,000 Meters to Kilometers 1,000 m = 1 km. Road distances, athletics tracks, geography. The daily-use metric distance unit. ÷ 1,000 Kilometers to Meters 1 km = 1,000 m. Converting map distances into working units for survey and civil engineering. × 1,000 Centimeters to Millimeters 1 cm = 10 mm. The simplest metric conversion — move the decimal one place. Shop floor habit. × 10 Millimeters to Centimeters 10 mm = 1 cm. Moving from machining precision to everyday dimensions. ÷ 10 Centimeters to Yards 1 cm ≈ 0.01094 yd. Uncommon but occasionally needed for textile and carpet imports. ÷ 91.44 Yards to Centimeters 1 yd = 91.44 cm. Fabric by the yard for metric pattern makers. Home sewing, tailoring. × 91.44

Miles & Kilometers

Miles to Kilometers 1 mi = 1.609344 km. The most-typed distance conversion. Road signs, marathon splits, GPS. × 1.609344 Kilometers to Miles 1 km ≈ 0.6214 mi. 5K = 3.1 miles, 10K = 6.2 miles. Every runner's mental math. ÷ 1.609344 Meters to Miles 1 m ≈ 0.0006214 mi. Track events: 1,600 m ≈ 0.994 mi — the metric mile that's 9.3 m short. ÷ 1,609.344 Miles to Meters 1 mi = 1,609.344 m. Converting race distances for international competition standards. × 1,609.344 Meters to Yards 1 m ≈ 1.0936 yd. Swimming: short course (25 yd) vs long course (50 m). Pool conversions. ÷ 0.9144 Yards to Meters 1 yd = 0.9144 m. Swimming, track and field, golf — sports are full of yard-to-meter conversions. × 0.9144

Nautical & Maritime

Nautical Miles to Kilometers 1 NM = 1.852 km. One minute of latitude at the meridian. The standard for all marine and air navigation. × 1.852 Kilometers to Nautical Miles 1 km ≈ 0.54 NM. Converting overland distances to navigation charts. ÷ 1.852 Nautical Miles to Miles 1 NM ≈ 1.1508 mi. A nautical mile is 15% longer than a statute mile. Boaters and pilots know this. × 1.15078 Miles to Nautical Miles 1 mi ≈ 0.869 NM. Converting road distances to nautical charts for coastal navigation. × 0.868976

Astronomical

Astronomical Units to Kilometers 1 AU = 149,597,870.7 km. The mean Earth-Sun distance, fixed by IAU in 2012. Solar system scale. × 149,597,870.7 Kilometers to Astronomical Units 1 km = 6.685 × 10⁻⁹ AU. Interplanetary mission planning. Useful above about 10 million km. ÷ 149,597,870.7 AU to Miles 1 AU ≈ 92,955,807 mi. The Earth-Sun distance in miles. NASA public communications. × 92,955,807 Miles to AU 1 mi ≈ 1.076 × 10⁻⁸ AU. Micro-scale within the solar system. Rarely practical but occasionally needed. ÷ 92,955,807 Light-Years to Kilometers 1 ly ≈ 9.461 × 10¹² km. The distance light travels in one Julian year. Stellar and galactic scales. × 9.461e12 Kilometers to Light-Years 1 km ≈ 1.057 × 10⁻¹³ ly. For perspective: Voyager 1 is about 0.0026 light-years out. Took 47 years. ÷ 9.461e12

Exact conversion factors

Every ordinary length conversion traces back to one treaty and one geometric definition. The table gives the exact factors rather than rounded approximations, because a rounded factor is the thing that shows up as a discrepancy downstream.

From	To	Exact factor	Basis
1 inch	centimeters	2.54	Exact, 1959 International Yard and Pound Agreement
1 foot	meters	0.3048	Exact, same agreement
1 yard	meters	0.9144	Exact, 3 feet
1 mile	kilometers	1.609344	Exact, 5,280 feet
1 nautical mile	kilometers	1.852	Exact, 1929 International Hydrographic Conference
1 meter	feet	3.28083989501	Derived from 1 ft = 0.3048 m
1 kilometer	miles	0.621371192237	Derived from 1 mile = 1.609344 km
1 millimeter	inches	0.0393700787402	Derived, 1 in = 25.4 mm
1 astronomical unit	kilometers	149,597,870.7	Exact, IAU 2012 definition of the astronomical unit
1 light-year	kilometers	9,460,730,472,580.8	Exact, c times one Julian year of 365.25 days

Defining values and exact constants

One inch is exactly 2.54 centimeters and one foot exactly 0.3048 meters. The 1959 International Yard and Pound Agreement replaced two slightly different national definitions with a single number.
A nautical mile is 1,852 meters exactly, which is one minute of latitude. That is why aviation and marine navigation still use it: distance and angular position are the same measurement.
A light-year is 9,460,730,472,580.8 km exactly. Both terms are defined, the speed of light and the length of a Julian year, so the figure carries no uncertainty.
The US survey foot was 1200/3937 m, about 2 parts per million longer than the international foot. It was retired on 31 December 2022 and federal surveys now use 0.3048 m.
The 1,609.344 m mile is a statute mile. A US survey mile of 5,280 survey feet was 1,609.347 m, which is why old American property deeds drift from modern maps.

Frequently asked questions

How many centimeters are in an inch?

Exactly 2.54. That is a definition rather than a measurement, so 10 inches is 25.4 cm and 100 inches is exactly 254 cm with no rounding at any point.

Why is a nautical mile different from a statute mile?

A nautical mile is 1,852 meters and tracks latitude, while a statute mile is 1,609.344 meters and tracks land survey. One minute of latitude equals one nautical mile, which is what makes chart work possible.

Is the US survey foot the same as a foot?

Almost. The survey foot was 1200/3937 m, two parts per million longer than the international foot of 0.3048 m. That is 0.01 feet per mile, and the unit was retired at the end of 2022.

How many feet are in a meter?

3.280839895, which is the reciprocal of 0.3048. Ten meters is 32.8084 feet and 100 meters is 328.084 feet, because the whole range scales by one fixed factor.