Length Converter — Metric & Imperial
Convert between mm, cm, metres, km, inches, feet, yards and miles. Includes feet & inches display.
By Konstantin Iakovlev · Founder, Calks.uk
Last updated: · Verified against HMRC and GOV.UK 2026/27 rates
Feet & Inches
3' 3.4"
Millimetres
1,000
Metres
1.00
Kilometres
1.00e-3
Inches
39.37
Feet
3.28
Yards
1.09
Miles
6.21e-4
Nautical Miles
5.40e-4
Disclaimer
This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.
How It Works
UK road signs use miles and yards, but most other measurements are metric. This converter handles metres, centimetres, millimetres, kilometres, feet, inches, yards and miles. It is particularly useful for property listings (square footage), DIY projects and running distances.
Key equivalents: one inch is 2.54 cm exactly, one foot is 30.48 cm, one yard is 0.9144 m, and one mile is 1.60934 km. The converter preserves full precision and also rounds to practical decimal places for everyday use.
UK imperial length units. 1 inch = 2.54 cm exactly (by definition since 1959). 1 foot = 12 inches = 30.48 cm. 1 yard = 3 feet = 0.9144 m. 1 mile = 1,760 yards = 5,280 feet = 1.609 km. Metric: 1 km = 0.621 miles. UK road signs use miles only (only major country alongside US to do so). Heights commonly in feet/inches (5'10") but medical records cm (178cm). Land surveying metric since 1995.
Common UK distance landmarks. Land's End to John o'Groats: 874 miles (1,407 km). London to Edinburgh: 405 miles (652 km). Channel crossing Dover-Calais: 21 miles (34 km). London Marathon: 26.2 miles (42.2 km). Premier League pitch: 100-110m × 64-75m. Athletics track: 400m. M25 ring: 117 miles (188 km). London Underground network: 250 miles (402 km) of track. Big Ben tower: 96m (315 ft). Shard: 310m (1,016 ft).
UK metrication history. UK metricated officially 1965-1995 but exempted: road signs, pints (beer/cider), pints (milk in glass bottles). EU stopped demanding metric road signs in 2009. Construction since 1980s metric only; property listings often dual-show ('lounge 14'6" × 12' / 4.42m × 3.66m'). Pilots and ships use nautical miles (1 NM = 1.852 km). UK driving licences in kg for vehicle weights since 2014.
Precision measurements for building. Trade builders use mm exclusively — never cm (avoids decimal errors). 2400mm board, not 2.4m. Standard UK door: 1981mm × 762/838mm. Brick: 215×102.5×65mm. Modern 'inch' timber sizes nominal — 2×4 actually 38×89mm planed. Tape measure: 5m DIY, 8m for trades. Laser measure: ±1.5mm accuracy to 30m, £30-£100. Surveying total stations: ±0.5mm over 100m.
Microscopic and astronomical scales. 1 micron (μm) = 0.001 mm — human hair 70μm wide. 1 nanometre (nm) = 0.001 μm — DNA double helix 2nm. Light year: 9.461 × 10^15 m (5.879 × 10^12 miles) — distance light travels in 1 year. Moon: 384,400 km (238,855 miles) average from Earth. Sun: 150 million km (93 million miles) average. Hubble telescope can resolve down to 0.05 arcseconds. UK has 50,000 miles of public road, 15,500 miles of railway track.
Example: Converting 5 feet 10 inches to metric
- 5 ft 10 in = 70 inches total
- 70 inches × 2.54 = 177.8 cm
- 177.8 cm = 1.778 m
Frequently Asked Questions
- UK length units — mile, yard, foot, inch.
- 1 inch = 2.54 cm (exact, by definition since 1959). 1 foot = 12 inches = 30.48 cm. 1 yard = 3 feet = 0.9144 m. 1 mile = 1,760 yards = 5,280 feet = 1.609 km. Metric: 1 km = 0.621 miles. UK road signs still use miles (only major country alongside US to do so). Heights commonly stated in feet/inches (5'10") but medical records use cm (178 cm). Land surveying: long-since metric (hectares since 1995).
- Common UK distance landmarks.
- Land's End to John o'Groats: 874 miles (1,407 km) by road. London to Edinburgh: 405 miles (652 km). Channel crossing Dover-Calais: 21 miles (34 km). London Marathon: 26.2 miles (42.2 km). Premier League pitch: 100-110m × 64-75m. Athletics track: 400m. UK motorway speed limit signs in mph but distance markers every 1/10 mile (motorway 'driver location' signs). London Underground network: 250 miles (402 km) of track.
- Why UK uses miles but kilometres elsewhere.
- UK metricated officially 1965-1995 but exempted road signs, beer (pints), and milk (pints) under pressure from drivers/consumers. EU stopped demanding metric road signs in 2009. Construction since 1980s: metric only for new builds, but legacy UK home dimensions often imperial (8x10 room = 2.44m × 3.05m). Property listings often dual-show: 'lounge 14'6" × 12' (4.42m × 3.66m)'. Pilots and ships use nautical miles internationally (1 NM = 1.852 km).
- Precision measurements for building work.
- Trade builders use mm exclusively — never cm (avoids decimal mistakes). 2400mm board, not 2.4m. Standard UK door height 1981mm (78 inches), width 762/838mm. Standard ceiling 2.4m new builds, 2.5m+ older. Brick 215×102.5×65mm. Modern timber 'inch' sizes are nominal — 2x4 actually 38×89mm planed. Tape measure 5m for DIY, 8m for trades. Laser measures accurate to ±1.5mm to 30m.