Convert Inches to Centimeters

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The Challenge

Inches dominate US product specifications but most of the world uses centimeters. A 65-inch TV needs to fit a 170cm entertainment unit — will it fit? A 32-inch bicycle wheel needs a matching fender in centimeters. US lumber sold as 2×4 inches requires metric drilling templates. Sewing patterns from American brands list seam allowances in inches; European fabric is sold by the centimeter. The exact conversion is 1 inch = 2.54 centimeters. To estimate mentally, multiply inches by 2.5 — result is within 1.6%. A 12-inch ruler is 30.48cm. A 6-foot person (72 inches) is exactly 182.88cm. A 55-inch TV diagonal is 139.7cm.

Inches to Centimeters Conversion Chart

Inches (in)	Centimeters (cm)	Millimeters (mm)
1/8 in	0.318 cm	3.18 mm
1/4 in	0.635 cm	6.35 mm
1/2 in	1.270 cm	12.70 mm
3/4 in	1.905 cm	19.05 mm
1 in	2.540 cm	25.40 mm
2 in	5.080 cm	50.80 mm
3 in	7.620 cm	76.20 mm
4 in	10.160 cm	101.60 mm
5 in	12.700 cm	127.00 mm
6 in	15.240 cm	152.40 mm
7 in	17.780 cm	177.80 mm
8 in	20.320 cm	203.20 mm
9 in	22.860 cm	228.60 mm
10 in	25.400 cm	254.00 mm
12 in (1 ft)	30.480 cm	304.80 mm
18 in	45.720 cm	457.20 mm
24 in (2 ft)	60.960 cm	609.60 mm
30 in	76.200 cm	762.00 mm
36 in (1 yd)	91.440 cm	914.40 mm
48 in (4 ft)	121.920 cm	1219.20 mm
60 in (5 ft)	152.400 cm	1524.00 mm
66 in (5'6")	167.640 cm	1676.40 mm
70 in (5'10")	177.800 cm	1778.00 mm
72 in (6 ft)	182.880 cm	1828.80 mm
74 in (6'2")	187.960 cm	1879.60 mm
76 in (6'4")	193.040 cm	1930.40 mm

Screen Size Conversion: Inches to cm

Screen Size (inches)	Diagonal (cm)	Typical Width (cm)
21 in	53.3 cm	~46.8 cm
24 in	60.9 cm	~53.4 cm
27 in	68.6 cm	~60.2 cm
32 in	81.3 cm	~71.3 cm
43 in	109.2 cm	~95.8 cm
50 in	127.0 cm	~111.3 cm
55 in	139.7 cm	~122.5 cm
65 in	165.1 cm	~144.8 cm
75 in	190.5 cm	~167.1 cm
85 in	215.9 cm	~189.4 cm

Why the Conversion Factor is Exactly 2.54

The value 2.54 is not a measurement or approximation — it is a definition. In 1959, the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa signed the International Yard and Pound Agreement, defining the international yard as exactly 0.9144 meters. This makes 1 foot = 0.3048 meters and 1 inch = 0.0254 meters = 2.54 centimeters exactly. Before this agreement, the US used the survey inch (1/39.37 meters = 2.540005 cm) which differed from the British standard, causing minor discrepancies in land surveys. The 1959 definition eliminated this ambiguity for all practical measurement purposes.

Converting Feet and Inches to Centimeters

Multiply the feet value by 12 to convert to inches — 5 feet × 12 = 60 inches
Add the remaining inches — 60 + 10 = 70 inches total
Multiply total inches by 2.54 — 70 × 2.54 = 177.8 cm
Check: 5 feet 10 inches = 177.8 cm, 6 feet exactly = 182.88 cm

When Inches vs Centimeters Matter

Inches are required when ordering US-standard plumbing fittings, pipe, lumber, or hardware — a 3/4-inch pipe fitting will not match a 19mm metric fitting even though the dimensions are close.

Never mix inches and centimeters within a single technical drawing or CNC machining file — unit mismatches are a leading cause of manufacturing errors, producing parts that are 2.54× too large or small.

Step-by-Step Workflow

Enter your inch value in the input field

Centimeter result appears instantly below

Click swap arrow to reverse — convert cm back to inches

Specifications

Formula: centimeters = inches × 2.54
1 inch equals: 2.54 cm (exact, defined)
1 foot (12 in): 30.48 cm
1 yard (36 in): 91.44 cm
Quick estimate: multiply by 2.5 (1.6% error)
6 ft (72 in): 182.88 cm
55-inch TV diagonal: 139.70 cm

Best Practices

Multiply by 2.54 for exact result — no rounding in the conversion factor
Height reference: 5ft 10in = 177.8cm, 6ft = 182.88cm, 6ft 2in = 187.96cm
Screen sizes: 24in = 60.96cm, 27in = 68.58cm, 32in = 81.28cm, 55in = 139.7cm
US lumber: 2×4 actual size is 1.5×3.5in = 3.81×8.89cm
Shoe size reference: US men's size 10 last length ≈ 27.8cm

Frequently Asked Questions

How many centimeters is 1 inch?

1 inch equals exactly 2.54 centimeters. This is a defined exact value — the 1959 International Yard and Pound Agreement fixed 1 yard as 0.9144 meters, making 1 inch = 25.4 millimeters = 2.54 centimeters with no rounding.

How do I convert inches to cm without a calculator?

Multiply by 2.54 for exact results, or by 2.5 for a quick estimate (1.6% error). Examples: 10 inches × 2.5 = 25cm (exact: 25.4cm). 20 inches × 2.5 = 50cm (exact: 50.8cm). 72 inches × 2.5 = 180cm (exact: 182.88cm). The error compounds at larger values, so use the full 2.54 for precision work.

What is 5 feet 10 inches in centimeters?

5 feet 10 inches = 70 inches total. 70 × 2.54 = 177.8cm. Calculation: 5 feet × 12 = 60 inches, plus 10 = 70 inches, × 2.54 = 177.8cm. This is the average height for adult males in the US.

What is 6 feet in centimeters?

6 feet = 72 inches × 2.54 = 182.88cm. Note that 180cm is often colloquially described as '6 feet' but is actually 5 feet 10.9 inches. True 6 feet is 182.88cm — a difference of nearly 3cm.

How do TV screen sizes in inches convert to cm?

Multiply the screen size in inches by 2.54 to get the diagonal in centimeters. 43in=109.2cm, 50in=127cm, 55in=139.7cm, 65in=165.1cm, 75in=190.5cm, 85in=215.9cm. These are screen diagonal measurements, not the physical TV width. A 65-inch TV is typically about 145cm wide including the bezel.

What are US clothing sizes in centimeters?

Men's chest: 34in=86cm, 36in=92cm, 38in=97cm, 40in=102cm, 42in=107cm, 44in=112cm. Men's waist: 28in=71cm, 30in=76cm, 32in=81cm, 34in=86cm, 36in=91cm. Women's bust: 32in=81cm, 34in=86cm, 36in=92cm, 38in=97cm, 40in=102cm. Inseam: 28in=71cm, 30in=76cm, 32in=81cm, 34in=86cm.

How do I convert fractional inches to cm?

Convert the fraction to decimal first, then multiply by 2.54. Examples: 1/2 inch = 0.5 × 2.54 = 1.27cm. 1/4 inch = 0.25 × 2.54 = 0.635cm. 3/8 inch = 0.375 × 2.54 = 0.9525cm. 5/8 inch = 0.625 × 2.54 = 1.5875cm. 1 3/4 inches = 1.75 × 2.54 = 4.445cm. Fractional inches are common in US carpentry, machining, and sewing patterns.