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Convert Feet and Inches to Centimeters – Length Converter

This tool converts a length entered as feet and inches into centimetres using the international definition that 1 inch equals exactly 25.4 millimetres (2.54 centimetres). Enter whole or fractional inches; the converter treats feet and inches as a single linear measure before converting.

The result is appropriate for everyday use, engineering approximations, and documentation where a simple numeric centimetre value is required. For legal, calibration, or safety-critical measurements follow laboratory procedures and the referenced standards for measurement uncertainty and reporting.

Updated Nov 16, 2025

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Methodology

The converter applies the fixed, exact relationship defined by international standards: 1 inch = 25.4 mm exactly. Therefore all conversions are exact arithmetical operations based on that constant. This approach is consistent with guidance from national metrology institutes and SI conventions.

When high accuracy is required, account for measurement uncertainty (device resolution, operator error, environmental effects). For traceable or regulated measurements consult NIST, ISO, or the appropriate industry standard and document the measurement uncertainty and calibration status of instruments.

Worked examples

5 ft 10 in → (5*12 + 10) = 70 in → 70 * 2.54 = 177.80 cm

6 ft 0 in → (6*12 + 0) = 72 in → 72 * 2.54 = 182.88 cm

0 ft 11.5 in → (0*12 + 11.5) = 11.5 in → 11.5 * 2.54 = 29.21 cm

Key takeaways

Use the formula cm = (feet * 12 + inches) * 2.54 for exact arithmetic conversion.

For high-stakes or regulated measurements, combine this arithmetic conversion with calibrated instruments and documented uncertainty per NIST/ISO guidance.

Further resources

Expert Q&A

Why does the converter use 2.54 as the inch-to-centimetre factor?

By international agreement and SI convention, 1 inch is defined as exactly 25.4 millimetres, which equals exactly 2.54 centimetres. This exact definition is used in metrology and standards publications.

Can I enter fractional inches (for example 5 ft 7 3/8 in)?

Yes. Enter fractional inches as a decimal (for example 7.375 for 7 3/8). The calculation uses the decimal value and applies the exact conversion factor.

What rounding or precision should I use for the result?

For general use two decimal places (0.01 cm) is common. For technical or regulatory work, follow the precision and uncertainty reporting required by your industry or laboratory, and retain extra significant figures internally until final reporting.

Is this suitable for legal measurements or medical records?

This converter provides arithmetic conversion only. For legal, medical, or regulated measurements, use calibrated instruments, follow documented measurement procedures, and record measurement uncertainty and instrument calibration status as required by governing standards.

How do I convert centimetres back to feet and inches?

To convert back, divide centimetres by 2.54 to get total inches, then integer-divide by 12 to get feet and take the remainder as inches. For example: total_inches = cm / 2.54; feet = floor(total_inches / 12); inches = total_inches - feet*12.

Sources & citations