Length Converter — Convert Metres, Feet, Inches, Miles, and Kilometres
Length conversion is needed daily in the UK, which uses a mix of metric and imperial units: road signs in miles, height in feet and inches, distances in kilometres, fabric in metres. The free length converter on PublicSoftTools converts between any length units — metric (mm, cm, m, km) and imperial (inches, feet, yards, miles) — instantly, with a reference table for common conversions.
How to Use the Length Converter
- Open the length converter.
- Select the unit you are converting from (e.g., metres).
- Enter your value.
- The converter shows the equivalent in all other units instantly.
- Click any result to copy it. Use the dropdown to change the input unit without re-entering the number.
Length Conversion Reference Table
| Unit | = metres | = inches | = feet | = miles | Common uses |
|---|---|---|---|---|---|
| Millimetre (mm) | 0.001 | 0.0393701 | 0.00328084 | 6.214 × 10⁻⁷ | Used for precision engineering, rainfall measurement |
| Centimetre (cm) | 0.01 | 0.393701 | 0.0328084 | 6.214 × 10⁻⁶ | Common for height, fabric, small objects |
| Metre (m) | 1 | 39.3701 | 3.28084 | 0.000621371 | SI base unit of length; athletics track distances; room dimensions |
| Kilometre (km) | 1,000 | 39,370.1 | 3,280.84 | 0.621371 | Road distances in metric countries; weather system scales |
| Inch (in) | 0.0254 | 1 | 0.0833333 | 1.578 × 10⁻⁵ | US/UK; screen sizes, tyre widths, pipe diameters |
| Foot (ft) | 0.3048 | 12 | 1 | 0.000189394 | US/UK; aircraft altitude, building height, room dimensions |
| Yard (yd) | 0.9144 | 36 | 3 | 0.000568182 | US/UK; American football field, fabric, golf |
| Mile (mi) | 1,609.34 | 63,360 | 5,280 | 1 | UK road distances, US distances; 1 mile = 5,280 ft exactly |
| Nautical mile (nmi) | 1,852 | 72,913.4 | 6,076.12 | 1.15078 | Navigation; 1 nmi = 1 arc-minute of latitude; aviation and maritime |
| Light-year (ly) | 9.461 × 10¹⁵ | 3.725 × 10¹⁷ | 3.104 × 10¹⁶ | 5.879 × 10¹² | Astronomical; distance light travels in one year |
Reference: Familiar Lengths
| Object / distance | Metric | Imperial | Notes |
|---|---|---|---|
| Width of a human hair | ~70 µm (0.07 mm) | ~0.003 inch | Varies 17–180 µm depending on person and hair type |
| Standard credit card | 85.6 mm × 53.98 mm | 3.37 in × 2.125 in | ISO/IEC 7810 ID-1 standard |
| A4 paper (long side) | 297 mm | 11.7 in | International standard; US Letter = 279 mm (11 in) |
| Average adult male height (UK) | 175.3 cm (1.753 m) | 5 ft 9 in | NHS survey average; female average ~162 cm (5 ft 4 in) |
| London to Edinburgh by road | ~658 km | ~409 miles | Via the A1/M1 motorway route |
| Earth's diameter | 12,742 km | 7,918 miles | Mean diameter; slightly wider at equator than poles |
| Distance Earth to Moon | 384,400 km | 238,855 miles | Average distance; varies from ~356,500 km to ~406,700 km |
| Distance to the Sun (1 AU) | 149,597,870 km | 93 million miles | Astronomical Unit; used as baseline for solar system measurements |
Key Conversion Relationships
The most important exact conversion relationships between metric and imperial length units:
- 1 inch = 25.4 mm exactly (defined in 1959 international yard and pound agreement)
- 1 foot = 30.48 cm = 12 inches exactly
- 1 yard = 0.9144 m exactly = 3 feet
- 1 mile = 1,609.344 m = 5,280 feet exactly
- 1 km = 1,000 m; 1 mile ≈ 1.60934 km; 1 km ≈ 0.621371 miles
The "5/8" approximation: 5 miles ≈ 8 km (more precisely 5 miles = 8.047 km). This is useful for quick mental conversion of UK road distances to metric.
Height Conversion: Feet and Inches to Centimetres
In the UK, height is commonly expressed in feet and inches, while medicine and sport use centimetres:
Formula: Total inches = (feet × 12) + inches, then × 2.54 = centimetres
Common height conversions:
- 5'0" = 152.4 cm
- 5'4" = 162.6 cm
- 5'6" = 167.6 cm
- 5'9" = 175.3 cm
- 6'0" = 182.9 cm
- 6'3" = 190.5 cm
UK Road Sign Distances
UK road signs show distances in miles and yards (never metric). EU countries use kilometres and metres. This creates confusion for UK drivers on the continent and for visitors to the UK.
Key conversions for road travel:
- 10 miles ≈ 16.1 km
- 50 miles/hour = 80.5 km/h (UK speed limit signs are in mph; EU signs in km/h)
- 1 mile = 1,760 yards; ¼ mile ≈ 400 m (common road distance on UK signs)
The UK is one of only three countries still using miles for road distances (alongside the US and Liberia). Most Commonwealth countries switched to kilometres in the 1970s.
Astronomical Distances
For very large distances, standard length units become unwieldy. Astronomers use:
- Astronomical Unit (AU): Average Earth-Sun distance = 149,597,870 km. Used for distances within the solar system.
- Light-year (ly): Distance light travels in one year = 9.461 × 10¹⁵ m (about 9.5 trillion km). Used for distances to nearby stars.
- Parsec (pc): 3.086 × 10¹⁶ m = 3.26 light-years. Defined using parallax angle — the distance at which 1 AU subtends an angle of 1 arc-second. Used by professional astronomers; galactic distances use kiloparsecs (kpc) and megaparsecs (Mpc).
Common Questions
How many metres in a mile?
1 mile = 1,609.344 metres exactly (defined). Rounded to 1,609 m or 1.609 km for most purposes. To convert miles to kilometres: multiply by 1.60934. Quick mental approximation: multiply miles by 8 and divide by 5 (or multiply by 1.6).
How do I convert feet and inches to decimal feet?
Convert the inches portion to a decimal: decimal feet = feet + (inches / 12). Example: 5 feet 9 inches = 5 + (9/12) = 5.75 feet = 5.75 × 0.3048 = 1.7526 m. The length converter handles compound units (feet + inches input) directly.
What is a nautical mile and why is it different from a statute mile?
A nautical mile (1,852 m) is defined as one arc-minute of latitude along a meridian. This makes nautical miles convenient for navigation because chart measurements directly correspond to geographic coordinates. A statute mile (1,609.344 m) has no such geographic basis — it derives from the Roman mille passuum (1,000 double steps = about 1,480 m) and was standardised in England. Aviation uses nautical miles and knots (nautical miles per hour) internationally.
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Enter any length in metres, feet, inches, miles, kilometres, or any other unit for instant conversion to all other units.
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