Length & Distance Converter
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, and miles.
Enter a length value and select the unit to see instant conversions to all other units.
Conversions use exact defined factors, including 1 inch = 25.4 mm, 1 foot = 0.3048 m, and 1 mile = 1,609.344 m.
Millimetres (mm)
1,000 mm
Centimetres (cm)
100 cm
Kilometres (km)
0.001 km
Inches (in)
39.370079 in
Feet (ft)
3.28084 ft
Yards (yd)
1.093613 yd
Miles (mi)
0.000621 mi
The One Number That Connects Everything
In 1959, the international yard was defined as exactly 0.9144 metres. From that single agreement, every imperial-to-metric length conversion follows with zero rounding. One inch is exactly 25.4 mm. One foot is exactly 304.8 mm. One mile is exactly 1,609.344 metres. These aren't approximations, they're definitions.
Most of the world runs on metric. The US, Liberia, and Myanmar still use customary units widely. The UK sits somewhere in between, road signs in miles, height in feet and inches, but construction and medicine in metres and millimetres. This converter handles all of it instantly.
Conversion Quick Reference
| From | To | Multiply by | Example |
|---|---|---|---|
| Inches | Centimetres | 2.54 | 12 in = 30.48 cm |
| Feet | Metres | 0.3048 | 6 ft = 1.829 m |
| Yards | Metres | 0.9144 | 100 yd = 91.44 m |
| Miles | Kilometres | 1.60934 | 26.2 mi = 42.16 km |
| Centimetres | Inches | 0.3937 | 170 cm = 66.93 in |
| Metres | Feet | 3.2808 | 1.8 m = 5.91 ft |
| Kilometres | Miles | 0.6214 | 10 km = 6.21 mi |
Mental maths shortcut: For km to miles, multiply by 5 and divide by 8. So 80 km × 5 ÷ 8 = 50 miles. For miles to km, multiply by 8 and divide by 5. Both get you within 0.5% of the exact answer.
Metric Reference Table
Metric length units are powers of ten. That makes them easy to scale for science, engineering, medicine, craft, and ordinary product measurements.
| Metric unit | Exact relationship | Common use |
|---|---|---|
| 1 millimetre (mm) | 0.001 metres | Hardware, machining, small product dimensions |
| 1 centimetre (cm) | 10 mm, or 0.01 metres | Height, clothing, packaging, small household measurements |
| 1 metre (m) | 100 cm, or 1,000 mm | Rooms, furniture, fabric, building plans |
| 1 kilometre (km) | 1,000 metres | Road distance outside the US and UK road-sign context, running routes |
Imperial and US Customary Reference Table
The supported imperial units here use the international definitions: 1 inch = 25.4 mm exactly, 1 foot = 12 inches, 1 yard = 3 feet, and 1 mile = 1,760 yards.
| Imperial unit | Exact metric value | Exact imperial relationship |
|---|---|---|
| 1 inch (in) | 25.4 mm | Base inch definition |
| 1 foot (ft) | 0.3048 m | 12 inches |
| 1 yard (yd) | 0.9144 m | 3 feet, or 36 inches |
| 1 mile (mi) | 1,609.344 m | 1,760 yards, or 5,280 feet |
| 1 nautical mile | 1,852 m | Used in aviation and maritime navigation |
Height Conversion Table
The conversion people look up most. Feet/inches to centimetres for every common adult height:
| Feet & Inches | Centimetres | Metres |
|---|---|---|
| 5'0" | 152.4 | 1.524 |
| 5'2" | 157.5 | 1.575 |
| 5'4" | 162.6 | 1.626 |
| 5'6" | 167.6 | 1.676 |
| 5'8" | 172.7 | 1.727 |
| 5'10" | 177.8 | 1.778 |
| 6'0" | 182.9 | 1.829 |
| 6'2" | 188.0 | 1.880 |
| 6'4" | 193.0 | 1.930 |
The formula: (feet × 30.48) + (inches × 2.54) = total centimetres. So 5'8" = (5 × 30.48) + (8 × 2.54) = 152.4 + 20.32 = 172.72 cm.
Real-World Distances That Help You Visualise
Thickness of a credit card. About 0.04 inches.
Width of a pencil. About 0.4 inches, slightly less than half an inch.
Width of your thumb at the knuckle. Exactly 2.54 cm.
Length of a standard ruler. 30.48 cm. Roughly the length of your forearm from wrist to elbow.
A large stride. About 3 feet 3 inches. A kitchen worktop is roughly 90 cm high, a door handle about 1 m.
A 12-minute walk for most adults. 0.621 miles. About 3,281 feet.
A 20-minute walk. 1.609 km. 5,280 feet. Four laps of a standard running track.
The UK's Hybrid Measurement System
If you live in the UK, you already switch between systems without thinking about it. Here's the actual breakdown of what British people use in practice:
Uses Imperial
- Road distances and speed limits (miles, mph)
- Personal height (feet and inches)
- Beer and cider (pints)
- Screen sizes (inches, globally standard)
Uses Metric
- Construction and DIY (millimetres, metres)
- Medicine and science (mm, cm, m)
- Product labels and packaging (ml, g, cm)
- Running races (5K, 10K, marathon in km)
This is why a converter matters for UK users more than almost anyone else. You'll need to go from feet to metres for a building plan, then from miles to km when entering a race, all in the same week.
Worked Example: US Furniture in a UK Room
Suppose Aisha in Birmingham finds a desk listed by a US seller as 48 inches wide, 24 inches deep, and 30 inches high. She wants to check whether it fits a room measured in centimetres.
Width
48 in × 2.54 = 121.92 cm
Depth
24 in × 2.54 = 60.96 cm
Height
30 in × 2.54 = 76.2 cm
Rounded for shopping, the desk is about 122 cm by 61 cm by 76 cm. Use the exact values when checking a tight alcove or ordering a made-to-measure item.
Common Length Conversion Mistakes
Treating feet and inches as decimal feet
5'10" is 5 feet plus 10 inches, not 5.10 feet. Convert the feet and inches separately before adding.
Rounding too early
Keep the exact factor through the calculation, then round the final answer. Early rounding can matter in construction, sewing, and engineering.
Mixing miles and nautical miles
A statute mile is 1,609.344 m. A nautical mile is 1,852 m. They are not interchangeable in aviation, shipping, or navigation.
Assuming screen inches describe width
Screen size in inches is diagonal, not width. Use aspect ratio if you need the physical width or height of a monitor or phone.
Using rough shortcuts for official forms
Shortcuts are fine for mental estimates. For medical records, passports, sports entries, and building plans, use exact conversion factors.
Forgetting regional habits
A UK road distance may be in miles, a Canadian product listing may be in centimetres, and an Australian race may be in kilometres. Check the unit before comparing values.
Related Tools
How to use this tool
Enter the length or distance value
Select the source unit from the dropdown
View instant conversions to all other length units
Common uses
- Converting height between feet/inches and centimetres
- Calculating room dimensions for international furniture
- Converting running distances between km and miles
- Estimating travel distances in unfamiliar unit systems
- Checking product measurements across UK, US, Canadian, and Australian listings
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Frequently Asked Questions
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