Inches to Centimetres: The Complete Length Conversion Guide
Whether you're checking screen sizes, comparing furniture dimensions from an American website, figuring out if a parcel will fit in a box, or trying to understand what "6 foot 2" means in centimetres, length conversion comes up constantly in everyday life.
This guide covers everything you need to know about converting between inches, centimetres, feet and metres — with practical reference tables, the exact formulas, and some context on where each unit is actually used.
The basics: one inch is exactly 2.54 cm
The inch was formally defined as exactly 25.4 millimetres in 1959, as part of an international agreement between the United States, United Kingdom, Canada, Australia, New Zealand and South Africa. This is an exact definition, not an approximation — 1 inch = 25.4 mm = 2.54 cm, precisely.
To convert inches to centimetres: multiply by 2.54.
To convert centimetres to inches: divide by 2.54 (or multiply by 0.3937).
One foot = 12 inches = 30.48 cm. One yard = 3 feet = 91.44 cm. One metre = 100 cm = 39.37 inches = 3.281 feet.
Inches to centimetres reference table
| Inches | Centimetres | Millimetres |
|---|---|---|
| ¼ inch | 0.635 cm | 6.35 mm |
| ½ inch | 1.27 cm | 12.7 mm |
| 1 inch | 2.54 cm | 25.4 mm |
| 2 inches | 5.08 cm | 50.8 mm |
| 3 inches | 7.62 cm | 76.2 mm |
| 4 inches | 10.16 cm | 101.6 mm |
| 5 inches | 12.70 cm | 127 mm |
| 6 inches | 15.24 cm | 152.4 mm |
| 8 inches | 20.32 cm | 203.2 mm |
| 10 inches | 25.40 cm | 254 mm |
| 12 inches (1 ft) | 30.48 cm | 304.8 mm |
| 18 inches | 45.72 cm | 457.2 mm |
| 24 inches (2 ft) | 60.96 cm | 609.6 mm |
| 36 inches (3 ft / 1 yd) | 91.44 cm | 914.4 mm |
Height conversion: feet and inches to centimetres
Human height is one of the most common reasons people need to convert between these units. Americans and British people typically describe height in feet and inches; most other countries use centimetres or metres.
| Height (feet/inches) | Centimetres |
|---|---|
| 5'0" (5 feet) | 152.4 cm |
| 5'1" | 154.9 cm |
| 5'2" | 157.5 cm |
| 5'3" | 160.0 cm |
| 5'4" | 162.6 cm |
| 5'5" | 165.1 cm |
| 5'6" | 167.6 cm |
| 5'7" | 170.2 cm |
| 5'8" | 172.7 cm |
| 5'9" | 175.3 cm |
| 5'10" | 177.8 cm |
| 5'11" | 180.3 cm |
| 6'0" (6 feet) | 182.9 cm |
| 6'1" | 185.4 cm |
| 6'2" | 187.9 cm |
| 6'3" | 190.5 cm |
| 6'4" | 193.0 cm |
To convert feet and inches to centimetres: multiply the number of feet by 30.48, then add the number of inches multiplied by 2.54.
Example: 5'9" = (5 × 30.48) + (9 × 2.54) = 152.4 + 22.86 = 175.26 cm.
Screen sizes: the inch that never went away
Even in countries that have fully adopted the metric system, television and monitor screen sizes are still described in inches — globally. A "55-inch TV" is a 55-inch TV whether you buy it in Tokyo, Sydney or Berlin.
Screen size is measured diagonally. Here are the common screen sizes in both units:
| Screen diagonal (inches) | Screen diagonal (cm) |
|---|---|
| 13" | 33 cm |
| 15.6" | 39.6 cm |
| 24" | 61 cm |
| 27" | 68.6 cm |
| 32" | 81.3 cm |
| 40" | 101.6 cm |
| 43" | 109.2 cm |
| 50" | 127 cm |
| 55" | 139.7 cm |
| 65" | 165.1 cm |
| 75" | 190.5 cm |
Other common length contexts
Clothing and textiles: Fabric is sold by the yard in the US and sometimes the UK; by the metre in most other countries. 1 yard = 91.44 cm ≈ 0.914 metres. When buying fabric, it's worth noting that a metre is slightly longer than a yard — if a pattern calls for 2 yards and you're buying metres, 1.85 metres is a safe equivalent.
Paper sizes: The US uses letter size (8.5" × 11") and legal size (8.5" × 14"). Most other countries use the ISO A4 standard (210 mm × 297 mm, or approximately 8.27" × 11.69"). A4 is slightly narrower and slightly taller than US letter.
Bike and tyre sizes: Bicycle wheels use a mixture of inch measurements (common for mountain bikes and older road bikes) and ISO/ETRTO metric measurements. A 26-inch wheel is approximately 660 mm in diameter. Modern road bikes often use 700c wheels, which is approximately 622 mm diameter in the ISO standard.
Need to convert between inches, centimetres, feet, metres and more? ConvertStuffNow's length converter handles all common length and distance units — just type in your number and get an instant result.
A useful mental shortcut
The exact conversion — multiply inches by 2.54 — isn't always easy to do in your head. A close approximation: multiply by 2.5 and add 2% (or just accept the 2% error).
For rough estimates: 10 inches ≈ 25 cm. 20 inches ≈ 50 cm. 40 inches ≈ 100 cm. These are easy anchor points to work from when you need a quick sense of scale without a converter.
All conversion values are exact, based on the 1959 international definition of the inch as 25.4 mm exactly. Screen sizes are measured diagonally and may vary slightly between manufacturers.