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
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.