18 inches in cm

45.72 cm

18 in = 45.72 cm = 457.2 mm = 0.4572 m

Working: 18 × 2.54 = 45.72

18 inches is 45.72 centimetres, or 457.2 millimetres.

The conversion is exact rather than approximate: since 1959 the international inch has been defined as precisely 2.54 centimetres, so multiplying by 2.54 gives an exact answer with no rounding error. 18 × 2.54 = 45.72 cm. To go back the other way, divide by 2.54; for millimetres, multiply the inches by 25.4 instead.

Metric trades work in millimetres rather than centimetres, and 18 inches is 457.2 mm — the figure a drawing or a parts list would actually carry. The nearest whole centimetre is 46, 0.28 cm away. In feet that is 1.5.

Eighteen inches is a standard cabinet depth and a common nominal spacing in framing. It converts to 45.72 cm, which European kitchen systems round to 45 — one of many places where a nominal imperial size and its metric counterpart are near neighbours rather than equivalents.

Nearby lengths

Inches	Centimetres
5 in	12.7 cm
6 in	15.24 cm
8 in	20.32 cm
10 in	25.4 cm
12 in	30.48 cm
15 in	38.1 cm
24 in	60.96 cm
27 in	68.58 cm

Try another value

From

3.2808ft

All units

Millimeters1,000 mm

Centimeters100 cm

Meters1 m

Kilometers0.001 km

Inches39.3701 in

Feet3.2808 ft

Yards1.0936 yd

Miles0.00062137 mi

Nautical miles0.00053996 nmi

Frequently asked questions

How many cm is 18 inches?

18 inches is 45.72 cm. Multiply the number of inches by 2.54 to convert to centimetres.

Is the inch to cm conversion exact?

Yes. The international inch has been defined as exactly 2.54 centimetres since 1959, so the conversion introduces no rounding error.

For any other value, use the full Length Converter on BrainVert.