Inches to Cm Converter
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Convert inches to centimeters (and back) instantly. Exact factor since 1959: 1 in = 2.54 cm — useful for height, screen sizes, and DIY measurements.
Inches
in
Centimeters
cm
1 in = 2.54 cm
Convert Inches
Quick presets
Centimeters
30.48 cm
12 in = 30.48 cm
- 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
- 48 in
- 121.92 cm
- 60 in
- 152.4 cm
- 72 in
- 182.88 cm
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Inches vs centimeters
Inches are the everyday imperial length for US height charts, TV diagonals, and DIY tape measures. Centimeters are the metric counterpart used on clothing tags, medical growth charts, and most rulers outside the US. Since 1959 the international inch has been locked to the metric system: 1 inch = exactly 2.54 centimeters (25.4 mm).
Worked example: a height of 5 ft 10 in is (5 × 12) + 10 = 70 inches. 70 × 2.54 = 177.8 cm. The same factor turns a 55-inch TV diagonal into about 139.7 cm — still measured corner to corner, not width or height.
Caveat: converting the number does not make paper sizes interchangeable. US Letter (8.5 × 11 in) and A4 (210 × 297 mm) are close but not the same; printers and binders care about the real sheet, not just a cm conversion of one dimension.
Round-trip sanity check: 12 in × 2.54 = 30.48 cm; 30.48 ÷ 2.54 = 12 in exactly. Height math fails when people convert feet and inches separately with rounding — convert total inches first, then multiply by 2.54 once.
Common questions
How do I convert height like 5 ft 10 in to centimeters?
Convert feet to inches first (feet × 12), add the remaining inches, then multiply by 2.54. Example: 5 ft 10 in → (5 × 12) + 10 = 70 in → 70 × 2.54 = 177.8 cm. Round-trip: 177.8 cm ÷ 2.54 = 70 in.
Why is 2.54 cm per inch exact while other conversions use long decimals?
The inch was redefined in 1959 to match metric exactly — 1 in = 25.4 mm with no repeating decimal. That makes inch↔cm conversions exact in both directions, unlike mile↔km factors with six decimal places.
Are TV and monitor sizes converted the same way?
Screen sizes are measured diagonally. A 55-inch TV is 55 inches corner to corner — about 139.7 cm diagonally, not width or height. Aspect ratio stays the same; only the diagonal length converts. Round-trip: 139.7 cm ÷ 2.54 ≈ 55 in.
Is the inch exactly 2.54 cm everywhere?
Yes. The international inch has been defined as exactly 25.4 mm (2.54 cm) since 1959, so US and metric countries use the same conversion factor today.
Paper sizes: is US Letter comparable to A4 if I convert inches to cm?
US Letter is 8.5 × 11 in (about 21.6 × 27.9 cm). A4 is 210 × 297 mm. They are close in width but not identical — do not assume they interchange in printers or binders.