Instantly convert any length or distance between metric, imperial, nautical, and astronomical units.
A length converter is a tool that lets you switch instantly between different units used to express distance or size. Whether you are reading a floor plan in centimetres, planning a walk in miles, buying fabric by the yard, or studying atomic physics in nanometres, a length converter eliminates the risk of arithmetic errors and saves time.
Length units vary widely by country, era, and field of study. In the United Kingdom, everyday distances are stated in miles on road signs, whereas metric units — metres and kilometres — dominate science, engineering, and most product labelling under the 1985 Weights and Measures Act. Having a single tool that covers everything from picometres to light-years ensures you always have the right figure at hand.
All conversions use a two-step method: the source value is first converted to metres (the SI base unit), then from metres to the target unit.
where f is the number of metres per unit (the conversion factor). For example, 1 foot = 0.3048 m, and 1 kilometre = 1,000 m.
The average height for a man in the United Kingdom is approximately 175.3 cm (5 ft 9 in) and for a woman around 161.9 cm (5 ft 4 in). Clothing sizes and medical records in the UK use both centimetres and the traditional feet-and-inches format, making this a common everyday conversion.
The Shard stands 309.6 m (1,016 ft) tall, making it the tallest building in the United Kingdom. Architectural drawings specify heights in metres, yet media reports often include the feet figure for readers more familiar with imperial units.
The road distance from London to Edinburgh along the A1 is approximately 665 km (413 miles). UK road signs display distances in miles, while sat-nav systems may switch between kilometres and miles depending on the driver's preference.
A regulation cricket pitch measures exactly 22 yards (66 ft or approximately 20.12 m) between the two sets of stumps. This historical unit — one chain — dates from the Gunter's chain surveying system and persists in cricket's laws unchanged since 1744.
Type any length value into the input field at the top of the converter.
Choose the unit your value is already in using the dropdown. Units are grouped into Metric, Imperial/US, and Others for easy navigation.
The converter instantly displays results in the three grouped sections: Metric (mm, cm, m, km), Imperial/US (in, ft, yd, mi), and Others (nmi, solar radii, light-years).
Expand the collapsed 'Other' grids in each section to see additional units — including mixed display formats such as metres + centimetres or feet + inches.
To convert in a different direction, simply select the new source unit from the dropdown and the results refresh immediately without any need to re-enter the value.
1 inch = exactly 25.4 mm. This is the exact, legally defined relationship between inches and the metric system since 1959.
1 nautical mile = 1,852 m. One nautical mile corresponds to one minute of arc of latitude, which is why it underpins global maritime and aviation navigation.
1 light-year ≈ 9.46 × 10¹⁵ m. Light travels approximately 9.46 quadrillion metres in a year, making light-years the standard unit for interstellar distances.
The ångström (Å = 10⁻¹⁰ m) is widely used in physics and crystallography to express atomic radii and wavelengths of visible light (roughly 4,000–7,000 Å).
Thou (mil) = 1/1000 of an inch = 25.4 μm. Machinists, printers, and electronics engineers use thou to specify tolerances far below what is visible to the naked eye.
There are exactly 2.54 centimetres in one inch. This is an exact, internationally agreed figure defined in 1959. So 12 inches (1 foot) = 30.48 cm, and 36 inches (1 yard) = 91.44 cm.
Multiply the number of feet by 0.3048 to get metres. For example, 6 feet = 6 × 0.3048 = 1.8288 m. Conversely, multiply metres by 3.28084 to get feet. The converter on this page handles all of this automatically.
A statute (land) mile is exactly 1,609.344 m, while a nautical mile is exactly 1,852 m — about 15% longer. Nautical miles are used in sea and air navigation because one nautical mile equals one minute (1/60 of a degree) of geographic latitude.
One light-year is approximately 9,460,730,472,580.8 km — roughly 9.46 trillion kilometres, or about 5.88 trillion miles. It is the distance light travels through a vacuum in one Julian year (365.25 days).
An ångström (symbol Å) equals 10⁻¹⁰ metres, or 0.1 nanometres. It was named after the Swedish physicist Anders Jonas Ångström and is commonly used in atomic physics, chemistry, and crystallography to express atomic bond lengths and the wavelengths of X-rays and visible light.
This converter uses exact or high-precision conversion factors from international standards (SI, NIST, IEEE). Results are accurate to at least 10 significant figures — far more than required for any engineering, scientific, or everyday application.
This converter is provided for informational and educational purposes. For critical engineering, legal, or scientific measurements, always verify values using calibrated instruments or certified standards.