How many inches is 1 centimeter?

1 centimeter equals 0.3937 inches. To convert cm to inches, divide the centimeters by 2.54.

How tall is 170 cm in feet and inches?

170 cm is 66.93 inches, which is about 5 feet 7 inches.

Why is 1 inch exactly 2.54 cm?

Since 1959, the inch has been defined internationally as exactly 2.54 centimeters — so this conversion is exact, not approximate.

Centimeters to Inches (cm → in)

1 inch = 2.54 cm, exactly. Type in either box — the other converts instantly, in both directions.

Centimeters (cm)

Inches (in)

📐The formula

inches = centimeters ÷ 2.54 · centimeters = inches × 2.54

🧠The mental-math trick

Multiply the centimeters by 4, then knock off a zero. For 30 cm: 30 × 4 = 120 → 12 inches (exact: 11.81). That's because 1 cm ≈ 0.4 in. Going the other way, an inch is about two and a half centimeters.

📋Quick reference table

Centimeters	Inches	Good to know
1 cm	0.39 in	Width of a pencil
2.54 cm	1 in	The exact definition
10 cm	3.94 in	A smartphone's width
30 cm	11.81 in	A school ruler ≈ 1 foot
100 cm	39.37 in	1 meter
150 cm	59.06 in	≈ 4 ft 11 in
160 cm	62.99 in	≈ 5 ft 3 in
170 cm	66.93 in	≈ 5 ft 7 in
180 cm	70.87 in	≈ 5 ft 11 in

💡Where you'll need this

Heights on forms and dating profiles, TV and monitor sizes (always sold in inches), clothing and shoe measurements, furniture shopping, and DIY projects with plans from another country. Since 1959 the inch is defined as exactly 2.54 cm — one of the few conversions with no rounding at all.

🔗Related conversions

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