How To Convert Inches To Centimeters Calculator
Inches to centimetres is the rare conversion where the factor is exact by definition rather than measured, so the whole skill reduces to applying it in the right direction and reporting no more precision than the measurement earned.
Length in centimeters
177.8
- Same length in meters
- 1.778
- Same length in millimeters
- 1,778
- The inches restated as decimal feet
- 5.8333
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
cm = in x 2.54
- in
- Length measured in inches
- 2.54
- Centimetres per inch — exact by definition, not an approximation
- cm
- The same length in centimetres, always the larger number
- 0.3937007874
- Inches per centimetre, the reciprocal of 2.54, for converting back
How to check the result by hand
- 1
Decide which direction you are travelling
Inches to centimetres multiplies by 2.54; centimetres to inches divides by 2.54, which is the same as multiplying by 0.3937007874. Say the direction out loud before touching the calculator, because reversing it is the most common error and the result still looks plausible. The centimetre figure must be the larger of the two, and that check catches the mistake instantly.
- 2
Collapse feet and inches into a single number of inches
Multiply the feet by 12 and add the leftover inches. Six feet two inches becomes 6 x 12 + 2 = 74, and five feet ten inches becomes 70. Working with one integer removes both the decimal-feet confusion and the temptation to convert the two parts separately.
- 3
Multiply by 2.54
70 x 2.54 = 177.8. The factor is exact by definition, so carry it at full precision rather than shortening it to 2.5. This step introduces no rounding of its own; the only digits that matter are the ones you brought in with the measurement.
- 4
Shift to metres or millimetres if the context wants them
Divide by 100 for metres and multiply by 10 for millimetres. The same 177.8 centimetres is 1.778 metres and 1778 millimetres. Because metric prefixes are powers of ten, these are decimal shifts rather than new multiplications, and they must not change any significant figure.
- 5
Round once, at the end, to what the measurement supports
A height read to the nearest inch justifies 178 centimetres far more than 177.8000. If you also want the decimal-feet form, 70 / 12 = 5.8333333, which is the number standing behind the written 5 feet 10 inches. Round at the very end and quote the rounded value as your answer.
For worked examples, common mistakes and the limits of this formula, read the full How To Convert Inches To Centimeters page.