CM to Inches Converter
Enter a length in centimeters to get the equivalent in decimal inches, fractional inches rounded to the nearest 1/64, and a feet-and-inches breakdown. You can also run the conversion in reverse by entering a value in inches. The exact conversion factor is 1 inch = 2.54 cm exactly, as defined by the international yard and pound agreement of 1959.
The exact conversion factor: 1 inch = 2.54 cm
The relationship between centimeters and inches is exact and fixed by international treaty. In 1959, the United States, United Kingdom, Australia, Canada, New Zealand, and South Africa agreed that the international yard equals exactly 0.9144 metres. Dividing by 36 gives the inch: exactly 0.0254 metres, or 2.54 centimeters. Because the factor is exact, converting cm to inches is as simple as dividing by 2.54, and converting inches back to cm is multiplying by 2.54. There is no rounding error in the definition itself: any imprecision comes only from the precision of your original measurement.
Decimal inches vs. fractional inches: which to use
Engineers, architects and machinists often use decimal inches (e.g. 11.8110 in) because they are easier to work with in calculations. Carpenters, plumbers and hardware suppliers in the United States frequently prefer fractional inches expressed in powers of two: halves, quarters, eighths, sixteenths, thirty-seconds, and sixty-fourths. This calculator shows both. The fractional result rounds to the nearest 1/64 inch, which is the finest graduation on most imperial rules and sufficient for virtually all practical work. If you need greater precision, use the four-decimal result and keep it decimal.
Feet and inches: the everyday format for heights and room sizes
In the United States and United Kingdom, heights and room dimensions are typically given in feet and inches rather than total inches. To convert: divide total inches by 12 to get whole feet, and keep the remainder as inches. For example, 175 cm is 68.898 in, which is 5 feet 8.898 inches (often rounded to 5 ft 9 in). This calculator does that step automatically so you see all three formats at once: the decimal inch (for math), the fractional inch (for measurements), and the feet-plus-inches breakdown (for everyday communication).
Reverse conversion: inches to centimeters
To go from inches back to centimeters, multiply by 2.54. Select "Inches to Centimeters" in the direction toggle at the top and type your inch value. This is useful when you have an imperial measurement (clothing sizes, screen diagonals, pipe diameters) and need to express it in metric. Common conversions: 1 in = 2.54 cm, 6 in = 15.24 cm, 12 in = 30.48 cm, 24 in = 60.96 cm, 36 in = 91.44 cm (exactly 1 yard).
Centimeters to Inches Conversion Table
| Centimeters (cm) | Decimal Inches (in) | Fractional Inches | Feet + Inches |
|---|---|---|---|
| 1 | 0.3937 | 25/64 in | 0 ft 0.39 in |
| 2 | 0.7874 | 25/32 in | 0 ft 0.79 in |
| 5 | 1.9685 | 1 31/32 in | 0 ft 1.97 in |
| 10 | 3.9370 | 3 15/16 in | 0 ft 3.94 in |
| 15 | 5.9055 | 5 29/32 in | 0 ft 5.91 in |
| 20 | 7.8740 | 7 7/8 in | 0 ft 7.87 in |
| 25 | 9.8425 | 9 27/32 in | 0 ft 9.84 in |
| 30 | 11.8110 | 11 13/16 in | 0 ft 11.81 in |
| 50 | 19.6850 | 19 11/16 in | 1 ft 7.69 in |
| 60 | 23.6220 | 23 5/8 in | 1 ft 11.62 in |
| 100 | 39.3701 | 39 3/8 in | 3 ft 3.37 in |
| 150 | 59.0551 | 59 1/16 in | 4 ft 11.06 in |
| 180 | 70.8661 | 70 7/8 in | 5 ft 10.87 in |
| 200 | 78.7402 | 78 3/4 in | 6 ft 6.74 in |
Quick-reference values. Exact factor: 1 in = 2.54 cm.
Frequently asked questions
How many inches is 1 cm?
1 centimeter equals 0.3937 inches (to 4 decimal places). The exact value is 1/2.54, which is approximately 0.393700787... inches. For a quick mental estimate, 1 cm is just under 4/10 of an inch.
How many centimeters is 1 inch?
1 inch is exactly 2.54 centimeters. This is not an approximation: the inch has been defined as exactly 2.54 cm by international agreement since 1959.
What is 30 cm in inches?
30 cm equals 11.8110 inches (to 4 decimal places), which is 11 13/16 in fractional form and 0 ft 11.81 in as feet and inches. A standard 30 cm ruler is just under 12 inches (one foot) long.
What is 5 feet in centimeters?
5 feet is 60 inches. Multiplied by 2.54, that gives exactly 152.4 cm. Switch the direction toggle to "Inches to Centimeters" and enter 60 to see this instantly.
How do I convert cm to fractional inches?
Divide the centimeter value by 2.54 to get decimal inches. Then multiply the decimal part by 64, round to the nearest whole number, and express that as a fraction over 64 (simplify if possible). For example, 10 cm is 3.937 in, so the decimal part is 0.937, multiplied by 64 gives 59.97, rounded to 60/64, which simplifies to 15/16. So 10 cm is 3 15/16 in to the nearest 1/64.
Is 2.54 an exact number or an approximation?
It is exact. By international agreement, 1 inch = 2.54 cm with no trailing decimal places. This means centimeter-to-inch conversions have no theoretical rounding error in the factor itself. Any imprecision in your result comes from the precision of the input measurement, not the conversion factor.