Inches to cm Converter
Convert inches to centimeters for screen sizes, clothing, and international product dimensions.
How It Works
Formula: in to cm = value × 2.54
Example: 10 in = 25.4 cm
Note: 1 inch equals exactly 2.54 centimeters by the international definition adopted in 1959.
Common Uses
Quick Conversion Table
| in | cm |
|---|---|
| 1 | 2.54 |
| 5 | 12.7 |
| 10 | 25.4 |
| 50 | 127 |
| 100 | 254 |
| 500 | 1270 |
| 1000 | 2540 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.0001 cm
Precision Guidance
For everyday use, round to 1 decimal place. For engineering, keep 2-4 decimals.
Common Mistakes
The inch-to-cm factor is exact (2.54), not an approximation. Use 2.54, not 2.5, for accuracy.
Frequently Asked Questions
What is 1 inch in cm?
1 inch equals exactly 2.54 centimeters by international definition.
How do I convert inches to cm?
Multiply the inch value by 2.54. For example, 10 in × 2.54 = 25.4 cm.
Why is 2.54 the conversion factor?
Since 1959, the inch has been legally defined as exactly 2.54 cm worldwide.
Is this used for screen sizes?
Yes, TV and monitor screens are measured in inches diagonally; this converts them to centimeters.
Deep Dive Guide
Inches to CM: Complete Conversion Guide for US Measurements
Convert inches to cm with the exact 2.54 factor. Our guide covers screen sizes, furniture, and product specs for US shoppers.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 inch (in) = 25.4 millimetres (exact)
- EXACT1 foot (ft) = 0.3048 metres (exact, 12 in)
- EXACT1 yard (yd) = 0.9144 metres (exact, 3 ft)
- EXACT1 mile (mi) = 1609.344 metres (exact, 5280 ft)
- EXACT1 centimetre (cm) = 0.01 metre (definition)
Common Pitfalls & How to Avoid Them
US survey foot is deprecated
The old US survey foot (0.304800609601 m) was retired in 2023 in favor of the international foot (0.3048 m). Modern conversions use the international foot; mixing them drifts over long distances.
Inches vs. centimetres for screens
Display and wheel sizes are often rounded to the nearest convenient number; a "27-inch" monitor is nominal, not a precise 68.58 cm panel.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy