About the Inches to cm Calculator
Inches turn up in heights, screen sizes, clothing, furniture, tools and product specifications, but most of the world works in centimetres and millimetres. Converting an American or British measurement into metric is one of the most common everyday calculations — whether you are filling in a form that asks for height in centimetres, checking whether a 24-inch monitor fits a desk, or following instructions written in fractions of an inch.
This inches to cm calculator converts inches, or feet and inches together, to centimetres, and shows the result in metres and millimetres, the total in inches, and the value rounded to the nearest centimetre and half-centimetre.
How to Use the Inches to cm Calculator
Enter the inches. Decimals work, so 3/8 inch can be entered as 0.375.
If you have a height or length in feet and inches, enter the feet too. Leave feet at 0 for inches only.
The centimetres appear with metres, millimetres and rounded values.
The Formula
total inches = feet × 12 + inches
centimetres = total inches × 2.54
millimetres = total inches × 25.4Because an inch is defined as exactly 2.54 centimetres, the multiplication is exact; only the displayed result is rounded.
Step-by-Step Example
A height of 5 ft 10 in.
Total inches: 5 × 12 + 10 = 70 in
Centimetres: 70 × 2.54 = 177.8 cmSo 5 ft 10 in is 177.8 cm, or 1.778 m, usually written as 178 cm.
12 inches is 12 × 2.54 = 30.48 cm — exactly one foot.
Quick Reference
1 in = 2.54 cm 12 in (1 ft) = 30.48 cm
2 in = 5.08 cm 24 in = 60.96 cm
6 in = 15.24 cm 36 in (1 yd) = 91.44 cm
10 in = 25.4 cm 39.37 in ≈ 100 cmHeights in Feet and Inches
Heights are the most common reason to convert inches. Forms, medical records and passports in most countries ask for height in centimetres, while many people know their height only in feet and inches. The table gives common heights exactly:
5 ft 0 in = 152.4 cm 5 ft 8 in = 172.72 cm
5 ft 4 in = 162.56 cm 5 ft 10 in = 177.8 cm
5 ft 6 in = 167.64 cm 6 ft 0 in = 182.88 cmEach extra inch adds 2.54 cm, and each extra foot 30.48 cm, so it is easy to adjust from the nearest row.
Fractions of an Inch
Imperial measurements often use fractions: 1/2, 1/4, 1/8 and 1/16 of an inch. To enter one, divide the top number by the bottom: 3/8 is 0.375, 5/16 is 0.3125. Then 3/8 inch is 0.375 × 2.54 = 0.9525 cm, or 9.525 mm. Common fractions in millimetres:
1/16 in = 1.5875 mm 1/4 in = 6.35 mm
1/8 in = 3.175 mm 1/2 in = 12.7 mm
3/16 in = 4.7625 mm 3/4 in = 19.05 mmThese matter for drill bits, bolts, spanners and plumbing fittings, where an imperial size may be close to, but not the same as, the nearest metric one.
Screens, TVs and Wheels
Screen sizes are measured diagonally in inches. A 55-inch television is 139.7 cm across the diagonal, and a 27-inch monitor 68.58 cm. Bicycle and car wheel sizes such as 26, 27.5 and 29 inches, or a 17-inch alloy rim, also convert with the same factor: a 17-inch rim is 43.18 cm across.
Where Inches Still Rule
Even in countries that went metric decades ago, inches survive in particular trades. Plumbers in Britain and Europe still name many pipe threads in inches, although the pipes themselves are made to metric sizes; bicycle frames and tyres mix inch and metric sizes freely; and computer hardware uses inches for drive bays and screens. In the United States, inches remain the everyday unit for almost everything, from lumber and paper sizes to rainfall. When you work across the two systems, converting once, exactly, and writing both values down avoids mistakes later in a project.
Converting Areas and Volumes
The factor 2.54 applies to lengths only. For an area, square it: one square inch is 2.54 × 2.54 = 6.4516 square centimetres. For a volume, cube it: one cubic inch is 16.387064 cubic centimetres, or millilitres. So a 10 × 10 inch tile covers 645.16 cm², not 254 cm², and an engine of 350 cubic inches displaces about 5,735 cm³ — roughly 5.7 litres. Convert each dimension to centimetres first and then multiply, or use the squared and cubed factors directly.
Precision in Engineering Drawings
Engineering drawings from the US often give dimensions to three or four decimal places of an inch, such as 0.250 in, with a tolerance like ±0.005 in. Converting, 0.250 in is 6.35 mm and ±0.005 in is ±0.127 mm. Keep the same number of significant figures in the metric value as in the original, so the converted drawing implies neither more nor less accuracy than the designer intended.
Understanding Your Result
The headline is the length in centimetres.
The metres and millimetres line gives the same length in the other metric units.
The total inches line shows the combined inches, or the length in feet.
The rounded line gives the value to the nearest centimetre and half-centimetre, as heights and sizes are often written.
When Should You Use This Calculator?
Use it to convert a height in feet and inches to centimetres for forms and records.
Use it for screens, wheels, furniture and product sizes given in inches.
Use it for DIY and engineering measurements in fractions of an inch.
Use it for clothing and shoe measurements from imperial size charts.
Common Mistakes
Adding feet as decimals. 5 ft 10 in is 70 inches, not 5.10 × 12.
Dividing by 2.54. From inches to centimetres, multiply.
Rounding fractions too early. Convert 3/8 to 0.375 exactly before multiplying.
Confusing inches with centimetres on dual rulers. Check which scale you read before writing the figure down.
Assuming an imperial size equals the nearest metric one. A 1/2-inch bolt is 12.7 mm, not 12 or 13 mm.