Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, and more.
1 Meter = 3.2808 Foot
A length converter is a tool that instantly translates any distance or measurement between metric units (millimeters, centimeters, meters, kilometers) and imperial/US customary units (inches, feet, yards, miles), plus specialised units like nautical miles and light years. Whether you are sizing a room for renovation, reading a foreign product specification, converting a race distance, or working with astronomical data, a length converter eliminates the need to memorise conversion factors and prevents the manual arithmetic errors that plague unit switching.
The need for length conversion arises daily across construction, travel, medicine, science, and commerce. The metric and imperial systems coexist uncomfortably in the modern world: science uses metric universally, but the United States, the world's largest economy, still uses customary units for everyday measurements. Global e-commerce, international travel, and cross-border engineering make length conversion a core practical skill.
Before 1875, the measurement landscape was even more fractured. Every country — and often every city — had its own units. A French foot (pied du roi) differed from an English foot; a German mile was nothing like a Scottish mile. The Metre Convention of 1875, signed by 17 nations in Paris, created the International Bureau of Weights and Measures (BIPM) and began the slow global convergence toward the metric system. The 1959 International Yard and Pound Agreement then fixed the imperial units as exact multiples of metric, making all modern conversion factors precise by definition rather than approximation.
Digital length conversion tools have made this history irrelevant for practical purposes. Whether you need a one-off conversion or a full table showing a single measurement in a dozen units simultaneously, a modern converter delivers results in milliseconds. The challenge today is not computing the conversion — it is knowing which unit a source document uses, and ensuring you enter and read the correct one for your application.
This converter routes all calculations through a single base unit — the meter (SI base unit for length). Every input is first converted to meters using an exact factor, then from meters to the target unit. This two-step approach, called the base-unit method, ensures precision for all unit pairs without requiring a separate conversion factor matrix for every possible combination.
All imperial-to-metric conversions above are exact by international treaty. The converter uses these full-precision definitions rather than rounded approximations.
When you do not have a calculator handy, these approximations are accurate enough for most everyday purposes. Memorise two or three and you will rarely be stuck:
The table below shows 1 meter expressed in five commonly needed units. Use it as a quick reference when you do not have the converter open.
Every length conversion follows a two-step formula:
Step 1: Convert miles to meters: 26.2 miles × 1,609.344 m/mile = 42,164.8 m
Step 2: Convert meters to km: 42,164.8 m ÷ 1,000 m/km = 42.165 km
Cross-check: 26.2 × 1.60934 = 42.165 km ✓ — the official marathon distance is 42.195 km (26 miles 385 yards)
Linear conversion: 12 ft × 0.3048 = 3.6576 m; 15 ft × 0.3048 = 4.572 m
Area conversion: 3.6576 m × 4.572 m = 16.72 m²
Why not just convert 180 ft²? 180 ft² × (0.3048)² = 180 × 0.092903 = 16.72 m² — same answer, but you must square the factor.
Note: area scales as the square of the length factor. Never apply a length conversion factor directly to an area value.
Unit conversion errors have caused catastrophic real-world failures. In 1999, NASA lost the $327 million Mars Climate Orbiter because Lockheed Martin's navigation team sent thruster data in imperial units (pound-force seconds) while NASA's systems expected metric (newton-seconds). The spacecraft entered the Martian atmosphere at the wrong angle and was destroyed. In 1983, Air Canada Flight 143 ran out of fuel at 41,000 feet because ground crew calculated fuel mass in pounds instead of kilograms. Both errors share the same root cause: different unit systems applied to the same data without conversion.
In everyday life, length conversion mistakes create real costs: incorrect flooring orders, furniture that does not fit, construction overruns, and miscommunicated medical measurements. In an increasingly global economy — where a US designer specifies in feet and inches, a German manufacturer produces in millimeters, and an Australian client installs in meters — reliable unit conversion is not optional.
The metric vs. imperial divide shows up in consumer products more than most people realise. Clothing sizes vary internationally: a US size 8 dress corresponds to a UK size 12 and a European size 40 — different numbering systems rooted in different length conventions. TV screen diagonals are universally quoted in inches even in metric countries (a "55-inch" TV in France or Japan). Food packaging lists net weight in grams but volume in milliliters, while US equivalents use ounces and fluid ounces. Understanding these unit conventions helps consumers shop internationally without surprises.
The United States has not converted to metric for a complex mix of economic and historical reasons. The infrastructure cost of remarking every road sign, reprinting every construction manual, and retraining every tradesperson is enormous — estimates from the 1970s metrication push ran into billions of dollars. The 1975 Metric Conversion Act made conversion voluntary rather than mandatory, effectively stalling progress. Today, the US uses a hybrid: metric in science, medicine, the military, and pharmaceutical labeling, but imperial in everyday construction, real estate, and transport. This duality means every American professional working in a global context must be fluent in both systems.
5 kilometers × 0.621371 = 3.107 miles. In yards: 5,000 m ÷ 0.9144 = 5,468.1 yards. Most road races mark every kilometer and every mile. Knowing that 5 km ≈ 3.1 miles and a half marathon (21.0975 km) ≈ 13.1 miles helps runners pace correctly when crossing between countries or joining differently-measured races.
12 ft × 0.3048 = 3.658 m; 15 ft × 0.3048 = 4.572 m. Area = 3.658 × 4.572 = 16.72 m². European flooring tiles and paint are sold per m², so this conversion is essential. Add 10% waste margin: order for 18.4 m². The baseboard perimeter is 2 × (3.658 + 4.572) = 16.46 m of trim needed.
A standard 20-foot shipping container interior: 5.898 m long × 2.352 m wide × 2.393 m high (equivalent to 19.36 ft × 7.72 ft × 7.85 ft). Volume = 33.2 m³ = 1,172 cubic feet. Cargo manifests and customs declarations require metric measurements in most countries, while some US domestic freight documents still use feet and inches.
Confusing millimeters and centimeters
The most common error: 10 mm = 1 cm, not the reverse. A kitchen tile listed as 30 cm is 300 mm — entering 30 mm into a tiling calculator gives an area 100 times too small. Always confirm the unit from the spec sheet before plugging numbers into any formula. In engineering drawings, dimensions are almost always in mm, not cm.
Using 1 mile ≈ 1.6 km exactly
1 mile = 1.60934 km, not exactly 1.6. Using 1.6 introduces a 0.6% error — small for casual navigation but meaningful over long distances. At 100 miles, the error is 934 m. Use 1.60934 for precision work. The fraction 8/5 = 1.6 is a useful approximation for mental math, but flag it as an estimate.
Treating decimal feet as feet-and-inches
5.5 feet is not '5 feet 5 inches' — it is 5 feet 6 inches (0.5 × 12 = 6 inches). This error is endemic in US construction and real estate. Always multiply the decimal fraction by 12 to get inches. A room listed as 12.75 feet wide is 12 feet 9 inches — the 9-inch margin matters when fitting furniture.
Mixing nautical miles with statute miles
Navigational charts, aviation fuel calculations, and international territorial waters use nautical miles (1 nmi = 1.15078 statute miles). Using statute miles in a nautical calculation introduces a 15% error. A ship planning a 200 nmi voyage actually travels 230 statute miles — wrong fuel loading is a safety issue. Always specify nmi vs. mi in navigation contexts.
Assuming yards and meters are interchangeable
1 yard = 0.9144 m — a 9.4 cm shortfall per yard. Over 100 yards, the error is 9.4 m. In athletics, a 400-yard track (365.76 m) is meaningfully shorter than a 400-meter track. In fabric purchasing, ordering 2 yards instead of 2 meters of material leaves you 17.12 cm short of what the pattern requires.
Forgetting that area and volume conversions are not linear
Length units scale linearly, but area scales as the square and volume as the cube. 1 ft = 0.3048 m, but 1 ft² = 0.0929 m² (not 0.3048 m²), and 1 ft³ = 0.02832 m³ (not 0.3048 m³). Applying the length conversion factor to area or volume gives wildly wrong results. Always square (or cube) the factor: (0.3048)² = 0.09290 m²/ft².
Using cm in engineering drawings that require mm
Technical drawings, CNC programs, and 3D printer files almost universally use millimeters. Entering a 5 cm dimension as '5' in a mm-based program produces a part 10× too small. Before importing any measurement into CAD software, confirm the file's native unit. A mismatched unit in a CNC program can destroy a workpiece and, at worst, damage the machine.
Conversion results are only as meaningful as the precision of the original measurement. A surveyor measuring "6 feet" with a tape measure accurate to ±½ inch should report 1.83 m, not 1.8288 m — the extra decimal places imply a level of precision that was not in the original measurement. The rule: report results to the same number of significant figures as the least precise input. For rough estimates (building footprints, hiking distances), one or two decimal places in meters suffice. For precision manufacturing or geodesy, use the full conversion factor and maintain more significant figures throughout intermediate steps.
The exact relationships between imperial and metric units are defined by international treaty. The International Yard and Pound Agreement of 1959 fixed 1 yard = 0.9144 m exactly, making the inch, foot, and mile exact metric equivalents. The nautical mile was standardised at 1,852 m by the International Hydrographic Conference in 1929. The meter itself is defined by the BIPM (International Bureau of Weights and Measures) as the distance light travels in vacuum in 1/299,792,458 of a second. These definitions are exact — there is no measurement uncertainty in the conversion factors themselves, only in the original measurements being converted.
Many length units persist in specialised domains. Horse heights are still given in hands (4 inches = 10.16 cm). Horse race distances use furlongs (201.168 m). Typography uses points (1 pt = 1/72 inch = 0.3528 mm) and picas (12 pt = 4.2333 mm). Gemstone diameters are sometimes expressed in millimeters but set via caliper in thou (thousandths of an inch). Older US land surveys use chains (20.1168 m) and rods (5.0292 m), both still encountered in legal property descriptions. Knowing these units prevents misinterpretation of historical documents and specialised industry specifications.
Digital design has spawned its own ecosystem of length units that do not map cleanly onto physical measurements. A CSS pixel (px) is a reference unit defined by the W3C as 1/96 of an inch at a nominal viewing distance — but on a high-DPI (retina) screen, one CSS pixel may span two or four physical pixels. A CSS point (pt) equals 1/72 of an inch. An em is relative to the current font size: 1 em in a 16px context equals 16px. A viewport width unit (vw) is 1% of the browser window's width, making it inherently variable. DPI (dots per inch) and PPI (pixels per inch) describe display density: a 4K monitor at 27 inches has roughly 163 PPI, while a smartphone at 6 inches and 2K resolution reaches 490 PPI. When designing for print, 1 inch = 72 pt = 96 px at standard resolution — but at 300 DPI print resolution, one inch spans 300 physical dots. Understanding how these digital length units relate to physical inches and centimeters is essential for designers working across both screen and print, or exporting assets for devices with varying pixel densities.
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Multiply meters by 3.28084 to get feet. For example, 5 m × 3.28084 = 16.4042 ft. The exact factor is 1 m = 3.280839895 ft, derived from the 1959 international agreement that 1 inch = exactly 25.4 mm. To reverse, multiply feet by 0.3048. A quick mental estimate: multiply meters by 3.3 for a rough approximation — a 2-meter doorway is about 6.6 feet, or just under 6 feet 7 inches.
There are exactly 2.54 centimeters in one inch. This is an international definition established in 1959 and has no rounding — it is exact. Therefore, 1 foot = 30.48 cm and 1 yard = 91.44 cm. To convert inches to centimeters, multiply by 2.54. To convert centimeters to inches, divide by 2.54 or multiply by 0.393701. A 12-inch ruler is exactly 30.48 cm, and a standard A4 sheet (21 cm wide) is approximately 8.27 inches.
Multiply kilometers by 0.621371 to get statute miles. For example, 10 km × 0.621371 = 6.214 miles. A handy mental shortcut: multiply by 5 then divide by 8, since the ratio is very close to 5/8. So 100 km ÷ 8 × 5 = 62.5 miles (exact: 62.14 miles). To convert miles to kilometers, multiply by 1.60934. Road distance signs in Europe, Australia, and most of Asia use kilometers; the US and UK use miles.
A meter (1.09361 yd) is slightly longer than a yard (0.9144 m) — by about 9.36 cm or 3.68 inches. In athletics, a 100-meter sprint is equivalent to about 109.4 yards. When furnishing a room, a 3-yard piece of fabric is about 2.743 meters. The meter is the SI base unit for length used worldwide in science and most countries. The yard persists primarily in the US for football fields, fabric measurement, and landscaping.
There are exactly 5,280 feet in one statute mile. This historical number comes from the Roman mille passuum (1,000 paces = 5,000 Roman feet) adjusted to align with furlong-based English land measurement (8 furlongs × 660 feet = 5,280 feet). In metric: 1 mile = 1,609.344 meters = 1.609344 km. There is also a nautical mile (1,852 m = 6,076.12 ft) used in aviation and maritime navigation, and a survey mile (5,280 survey feet) used in older US land records.
A millimeter (mm) is one-thousandth of a meter (0.001 m = 0.03937 in). Millimeters are the workhorse unit for precision manufacturing, engineering drawings, medical imaging, and hardware specifications. Common references: a credit card is 0.76 mm thick, a standard mechanical pencil lead is 0.5 mm or 0.7 mm, a human hair is roughly 0.07 mm in diameter, and 25.4 mm = exactly 1 inch. In Europe, tire width is given in mm (e.g., 205/55R16 means 205 mm wide).
Multiply inches by 2.54 to get centimeters. For example, 6 inches × 2.54 = 15.24 cm. Since this conversion is exact, there is no rounding error. To convert centimeters to inches, divide by 2.54 or multiply by 0.393701. Practical uses: a 42-inch TV screen diagonal = 106.68 cm; a 5-foot-10-inch person = (70 in × 2.54) = 177.8 cm; a standard US letter page (8.5 in) = 21.59 cm wide.
A light year is the distance light travels in one Julian year (365.25 days) in a vacuum: exactly 9,460,730,472,580.8 km ≈ 9.461 × 10¹⁵ m ≈ 5.879 × 10¹² miles. It is used in astronomy because the universe is too vast for kilometers or miles to be practical. The nearest star system, Alpha Centauri, is about 4.37 light years away. The Milky Way galaxy is roughly 100,000 light years in diameter. A light year is not a unit of time — it is purely a distance.
One nautical mile = 1,852 meters = 1.15078 statute miles = 6,076.12 feet. A statute (land) mile = 1,609.344 meters = 5,280 feet. The nautical mile is based on the Earth's geometry: it equals one arcminute of latitude, making it ideal for navigation with charts. At 1 knot = 1 nautical mile per hour, a ship doing 20 knots travels 37.04 km/h. Nautical miles are used internationally in aviation, maritime navigation, and international law (e.g., territorial waters are defined as 12 nautical miles).
All but three countries officially use the metric system: the United States, Liberia, and Myanmar still use imperial or customary units as their primary everyday system. However, even the US uses metric in science, medicine, military, and many industries — product labels require both units. The UK uses metric officially but miles for road distances and pints for beer. Canada is officially metric but many Canadians use imperial for height, weight, and cooking. The metric system, introduced during the French Revolution, has been adopted by 96% of the world's population.
Multiply feet by 0.3048 to get meters. This is an exact conversion: 1 ft = 0.3048 m exactly. For example, a 6-foot person = 6 × 0.3048 = 1.8288 m. To convert meters back to feet, divide by 0.3048 or multiply by 3.28084. A practical shortcut: multiply feet by 3, then divide by 10 to get approximate meters (6 ft × 3 ÷ 10 = 1.8 m — close to exact 1.8288 m). This is useful for quickly estimating room dimensions in metric from imperial specs.
Metric length units use powers of 10: 1 m = 10 dm = 100 cm = 1,000 mm = 0.001 km. Moving between metric units requires only shifting a decimal point, making arithmetic simple. Imperial units use irregular multipliers: 12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile. This makes multi-step imperial conversions error-prone. Scientifically, metric (SI) units are universal. Engineering in the US uses both — structural drawings in feet and inches, precision machining in thousandths of an inch (thou) or millimeters.
There are exactly 1,000 millimeters in one meter. The SI prefix 'milli-' always means one-thousandth (10⁻³). So: 1 m = 1,000 mm; 1 mm = 0.001 m; 0.5 m = 500 mm. Converting meters to millimeters simply moves the decimal three places right: 2.5 m = 2,500 mm. This regularity is why the metric system dominates engineering and science — scaling between units never requires memorizing irregular conversion factors.
Multiply yards by 0.9144 to get meters (exact definition). For example, 50 yards × 0.9144 = 45.72 m. The US football field from goal line to goal line is 100 yards = 91.44 m. To convert meters to yards, divide by 0.9144 or multiply by 1.09361. In fabric and textile retailing, many US stores sell by the yard while European suppliers use meters — a 1.5-meter length is approximately 1.64 yards, or just under 1 yard 24 inches.
A micrometer (μm), informally called a micron, is one-millionth of a meter (10⁻⁶ m = 0.001 mm = 0.000039 in). It is used in biology (human red blood cells are 6–8 μm in diameter), semiconductor manufacturing (CPU transistors are measured in nanometers to a few μm), optical fiber specifications, and pollution measurement (PM2.5 refers to particulate matter ≤2.5 μm). A human hair is typically 17–181 μm wide. The mechanical micrometer gauge (machinist's tool) measures to ±1 μm precision.
An astronomical unit (AU) is defined as exactly 149,597,870,700 meters (about 149.6 million km or 92.96 million miles) — the mean distance from Earth to the Sun. It is used to express distances within the solar system. Jupiter orbits at about 5.2 AU; Neptune at about 30.1 AU; the outer edge of the Oort cloud is estimated at 50,000–200,000 AU. For interstellar distances, astronomers use light years or parsecs (1 parsec ≈ 206,265 AU ≈ 3.26 light years).
Multiply statute miles by 0.868976 to get nautical miles. For example, 100 miles × 0.868976 = 86.9 nautical miles. To convert nautical miles to statute miles, multiply by 1.15078. Alternatively, convert both through meters: 1 statute mile = 1,609.344 m; 1 nautical mile = 1,852 m; therefore 1 statute mile = 1,609.344 ÷ 1,852 = 0.8690 nautical miles. This conversion is frequently needed when translating road distances to maritime chart distances or aviation flight plans.
A furlong is exactly 201.168 meters (⅛ of a statute mile = 220 yards = 660 feet). Historically, it was the length a team of oxen could plow without resting. Today, furlongs survive almost exclusively in horse racing: US, UK, Australian, and Canadian race distances are still called in furlongs (e.g., the Kentucky Derby is 10 furlongs = 1.25 miles = 2,011.68 m). They also appear in older US land survey descriptions and the definition of an acre (10 square chains = 1 acre, where 1 chain = 1/10 furlong).
An angstrom (Å) is 10⁻¹⁰ meters = 0.1 nanometers = 100 picometers. It was originally defined to express wavelengths of visible light (400–700 nm = 4,000–7,000 Å) and atomic bond lengths (typical C–C bond ≈ 1.54 Å). Although the angstrom is not an SI unit, it persists in crystallography, spectroscopy, and atomic physics because atomic dimensions conveniently express as single-digit angstrom values. Modern usage increasingly favors nanometers (1 nm = 10 Å) as the SI-preferred unit for this scale.
Divide centimeters by 100 to get meters, since 1 m = 100 cm. For example, 175 cm ÷ 100 = 1.75 m. To convert meters to centimeters, multiply by 100. This is one of the most common conversions for everyday use — height measurements in medical and fitness contexts often use cm in Europe (e.g., 170 cm) while the same height is expressed in feet and inches (5 ft 7 in) in the US. Always double-check whether a spec sheet uses mm or cm to avoid a 10× dimensional error.
A parsec (pc) is the distance at which one astronomical unit subtends an angle of one arcsecond: exactly 3.085677581×10¹⁶ meters ≈ 3.26156 light years ≈ 206,265 AU. Astronomers prefer parsecs over light years because they arise directly from the parallax method of measuring stellar distances. The nearest star, Proxima Centauri, is 1.295 parsecs away. The Milky Way is about 30 kiloparsecs in diameter. Galaxy clusters are measured in megaparsecs (Mpc); the observable universe spans about 28.5 gigaparsecs.
There are exactly 12 inches in 1 foot and exactly 36 inches in 1 yard (3 feet). These ratios are fixed definitions. 1 foot = 12 in = 30.48 cm; 1 yard = 36 in = 3 ft = 91.44 cm. When expressing partial feet as inches, multiply the decimal part by 12: 5.75 feet = 5 feet + (0.75 × 12) = 5 feet 9 inches. Confusion between decimal feet and feet-and-inches is a common source of measurement errors in US construction and renovation.
A hand is exactly 4 inches = 10.16 cm, historically based on the width of a human hand including the thumb. It is the standard unit for measuring the height of horses and some ponies, measured from the ground to the withers (highest point of the shoulder). Heights are expressed as whole hands plus inches: 15.2 hh means 15 hands 2 inches = (15 × 4) + 2 = 62 inches = 157.48 cm. Horses under 14.2 hh (147.3 cm / 58 in) are classified as ponies in most disciplines.
Rounding introduces cumulative error. Converting 3 feet to cm: exact = 91.44 cm; if you round 1 ft ≈ 30 cm and multiply by 3, you get 90 cm — an error of 1.44 cm (1.6%). Over longer distances, rounding compounds: 100 miles using 1 mi ≈ 1.6 km gives 160 km vs. exact 160.934 km — off by nearly 1 km. Best practice: use the full conversion factor (0.3048 m/ft or 1.60934 km/mi) and round only the final result, not intermediate steps. This matters in navigation, construction, and manufacturing.
Since 1983: the distance light travels in vacuum in 1/299,792,458 seconds. This fixes the speed of light exactly and makes the meter reproducible anywhere without a physical artifact.
Divide millimeters by 25.4 to get inches (since 1 in = exactly 25.4 mm). For example, 100 mm ÷ 25.4 = 3.937 inches. Alternatively, multiply mm by 0.0393701. Common conversions: 10 mm = 0.394 in; 50 mm = 1.969 in; 25.4 mm = exactly 1 inch. This conversion is essential for purchasing fasteners, pipes, and fittings: metric M8 bolts (8 mm diameter) don't match 5/16-inch (7.94 mm) imperial hardware, but they are close — precise measurement matters for mechanical integrity.
A nautical mile was originally defined as one arcminute of latitude, which varies slightly because Earth is an oblate spheroid (flatter at the poles). The actual arc length of 1 arcminute ranges from 1,842.9 m at the equator to 1,861.7 m at the poles. In 1929, the International Hydrographic Conference standardized the nautical mile at exactly 1,852 m — close to the average — to enable consistent global navigation charts and international legal definitions. This fixed definition is now used in aviation, maritime law, and meteorology worldwide.
A statute mile = exactly 1,609.344 meters (defined in 1959 by international agreement). A US survey mile = 5,280 survey feet = approximately 1,609.3472 meters — a difference of about 3.2 mm per mile. This tiny discrepancy accumulated over large areas; in 1893, the US Metric Act defined the survey foot as 1200/3937 meters (≈ 0.30480061 m) for land surveys, while the international foot is exactly 0.3048 m. US survey feet have been officially deprecated since 2023, transitioning all geodetic work to international feet and meters.
Convert everything to inches first, then multiply by 2.54. Formula: cm = (feet × 12 + inches) × 2.54. Examples: 5 ft 10 in = (60 + 10) × 2.54 = 70 × 2.54 = 177.8 cm. 6 ft 2 in = (72 + 2) × 2.54 = 74 × 2.54 = 187.96 cm. To reverse — convert cm to feet and inches: divide cm by 2.54 to get total inches, then divide by 12 and take the quotient as feet and the remainder as inches. This conversion is needed for international medical records, passport applications, and online clothing purchases.
A chain (Gunter's chain) = 66 feet = 20.1168 m = 100 links = 4 rods. A rod (also called a pole or perch) = 16.5 feet = 5.0292 m = 25 links. An acre is defined as 10 square chains (660 ft × 66 ft = 43,560 sq ft). These units were designed so 80 chains = 1 statute mile. US legal property descriptions in older deeds still use chains and rods, so land surveyors and real estate attorneys must convert them to modern units. 1 chain = 20.1168 m; 1 rod = 5.0292 m.
Conversion method: All lengths are converted through the SI base unit (meter) using internationally defined exact factors per the 1959 International Yard and Pound Agreement, the 1929 IHO nautical mile definition, and BIPM SI Brochure (9th edition, 2019). Imperial-to-metric conversions are exact — there is no rounding in the conversion factors themselves.
Accuracy notes: The converter carries full floating-point precision (IEEE 754 double, ~15–17 significant digits) throughout every calculation and rounds only the displayed result. For values near zero or extremely large values (e.g., light years to millimeters), scientific notation is used automatically to avoid misleading trailing zeros. Unit labels follow the BIPM SI Brochure symbol conventions: m, cm, mm, km, in, ft, yd, mi, nmi, ly.
Data sources: NIST Special Publication 811 (2008 ed.); BIPM SI Brochure; International Hydrographic Organization Publication M-3. Disclaimer: For legal surveys, engineering tolerances, or safety-critical applications, verify with calibrated instruments and authoritative standards bodies. Results are for informational purposes. Last updated: June 2026. Maintained by Financial Growth Hub.
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