CM to Inches Converter
Convert centimeters to inches and inches to centimeters. Shows decimal and fractional inches with a quick reference table.
Quick Answer
1 inch = 2.54 cm exactly. Divide cm by 2.54 to get inches. Multiply inches by 2.54 to get cm. For example, 10 cm = 3.937 inches (about 3 15/16").
Formula
Inches = Centimeters / 2.54
Centimeters = Inches x 2.54
Common Conversions
| Centimeters | Inches |
|---|---|
| 1 cm | 0.394 in |
| 2 cm | 0.787 in |
| 2.54 cm | 1.000 in |
| 5 cm | 1.969 in |
| 10 cm | 3.937 in |
| 15 cm | 5.906 in |
| 20 cm | 7.874 in |
| 25 cm | 9.843 in |
| 30 cm | 11.811 in |
| 50 cm | 19.685 in |
| 100 cm | 39.370 in |
| 150 cm | 59.055 in |
| 152.4 cm | 60.000 in |
| 180 cm | 70.866 in |
| 200 cm | 78.740 in |
About This Tool
The CM to Inches Converter handles bidirectional conversion between centimeters and inches with both decimal and fractional inch output. These two units are among the most frequently converted measurements in the world, used in everything from clothing sizes to construction plans to medical records.
The Exact Relationship
One inch is defined as exactly 2.54 centimeters. This definition was established in 1959 by an international agreement among six English-speaking nations (the US, UK, Canada, Australia, New Zealand, and South Africa). Before this standardization, the inch varied slightly between countries. The British inch was 2.539998 cm, while the American inch was 2.540005 cm. The 1959 agreement eliminated these discrepancies and established the international inch at exactly 25.4 millimeters.
Fractional Inches
In the imperial system, measurements are often expressed as fractions rather than decimals. A carpenter might say a board is 3 and 1/4 inches wide rather than 3.25 inches. Common fractions used in everyday measurements go down to sixteenths of an inch (1/16, 1/8, 3/16, 1/4, 5/16, 3/8, and so on). In precision machining, measurements go to 32nds or 64ths of an inch. This tool shows the nearest common fraction for any conversion result, making it practical for woodworking, sewing, and construction.
Common Uses
Height measurement is one of the most frequent conversions. Medical records globally use centimeters, while Americans describe height in feet and inches. Knowing that 5 feet 10 inches equals 177.8 cm (or that 175 cm is about 5 feet 9 inches) helps when reading international health data. Clothing sizes are another common use case: European and Asian clothing often lists measurements in centimeters, while American sizing uses inches.
Screen sizes for TVs, monitors, laptops, and phones are always measured diagonally in inches, even in metric countries. A 27-inch monitor has a diagonal of 68.58 cm. Paper sizes differ too: US Letter paper is 8.5 x 11 inches (21.59 x 27.94 cm), while international A4 paper is 21 x 29.7 cm (8.27 x 11.69 inches). Understanding these conversions helps when shopping internationally, reading product specifications, or working with people in different countries.
Quick Mental Math
For rough mental conversion, remember that 1 inch is about 2.5 cm. So 10 cm is about 4 inches, 30 cm is about 12 inches (one foot), and 100 cm is about 39 inches. Going the other direction, 1 cm is about 2/5 of an inch. These approximations are within 2% of the exact values and are useful for quick estimates when precision is not critical.