Matemática

Convert Inches to Centimeters — TV, Monitor & Phone Screen Sizes

Q: How many cm is 55 inches (TV size)?

55 × 2.54 = **139.70 cm** diagonal. For a 16:9 TV: width ≈ 121.8 cm, height ≈ 68.5 cm. Your TV unit should be at least 125–127 cm wide to accommodate the physical frame.

Q: How many cm is 65 inches?

65 × 2.54 = **165.10 cm** diagonal. Width of a 16:9 65-inch TV ≈ 143.9 cm; height ≈ 81 cm. The physical chassis adds 3–5 cm per side.

Convert any screen size from inches to cm or cm to inches instantly. Exact factor: 1" = 2.54 cm. Includes reference table for the most common TV and monitor sizes (32", 43", 55", 65", 75").

🗓️ Updated June 2026 Reviewed by Martín Rodríguez

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Reviewed by: Martín Rodríguez (editorial policy ) · Last reviewed: Jun 16, 2026

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This converter instantly switches between inches and centimeters for screen sizes — TVs, monitors, tablets, smartphones, and laptops. Screen size is always measured diagonally, corner to corner across the active display area. The exact formula is: inches × 2.54 = centimeters (1 inch = 2.54 cm exactly, per the 1959 International Yard and Pound Agreement). Use this when buying a TV and checking if it fits your furniture, comparing products listed in different unit systems, or verifying spec sheet measurements.

When to use this calculator

Checking whether a 65-inch TV (165.1 cm diagonal) fits on a 150 cm wide TV unit — it doesn't, you need at least 158 cm of clearance.
Comparing a US-listed 55-inch TV with a European listing showing 139 cm to confirm they're the same panel before purchasing.
Converting a smartphone screen from 6.7 inches to 17.02 cm to match the spec sheet format required by a carrier or retailer.
Verifying that a 15.6-inch laptop display (39.62 cm) meets the minimum screen size requirement for a graphics-intensive software license.
Determining the physical diagonal of a 32-inch (81.28 cm) TV to choose the correct VESA wall-mount bracket reach and arm length.

Common screen sizes: diagonal inches to cm (16:9)

Diagonal converts at 1 inch = 2.54 cm. Width and height assume a 16:9 aspect ratio (most monitors and TVs).

Size	Diagonal (cm)	Width (16:9)	Height (16:9)
13.3"	33.8 cm	29.4 cm	16.6 cm
15.6"	39.6 cm	34.5 cm	19.4 cm
24"	61.0 cm	53.1 cm	29.9 cm
27"	68.6 cm	59.8 cm	33.6 cm
32"	81.3 cm	70.8 cm	39.8 cm
55"	139.7 cm	121.8 cm	68.5 cm
65"	165.1 cm	143.9 cm	80.9 cm
75"	190.5 cm	166.0 cm	93.4 cm

How it works

How It's Calculated

The inch-to-centimeter relationship is exact — not an approximation — established by international agreement and codified by NIST:

inches → centimeters:  cm  = inches × 2.54
centimeters → inches:  in  = cm ÷ 2.54

Example 1:  55 in × 2.54 = 139.70 cm
Example 2:  165.10 cm ÷ 2.54 = 65.00 in

Screen size always refers to the diagonal measurement of the active display area, not the width or height, and does not include the bezel (frame).

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Inches to CM — Screen Size Reference Table

Screen Size (in)	Screen Size (cm)	Width 16:9 (cm)	Height 16:9 (cm)	Common Device
4.7	11.94	10.4	5.9	Smartphone (small)
6.1	15.49	13.5	7.6	iPhone 15
6.7	17.02	14.8	8.3	Large smartphone
10.9	27.69	24.1	13.6	iPad Air
13.3	33.78	29.5	16.6	Laptop (common)
15.6	39.62	34.5	19.4	Standard laptop
24.0	60.96	53.1	29.9	Office monitor
27.0	68.58	59.8	33.6	Popular monitor
32.0	81.28	70.8	39.8	Large monitor / small TV
40.0	101.60	88.6	49.8	Mid-size TV
43.0	109.22	95.2	53.6	43-inch TV
50.0	127.00	110.7	62.3	50-inch TV
55.0	139.70	121.8	68.5	55-inch TV
65.0	165.10	143.9	81.0	65-inch TV
75.0	190.50	166.1	93.4	75-inch TV
85.0	215.90	188.3	105.9	85-inch TV

16:9 formulas: width = diagonal × 0.872; height = diagonal × 0.490.

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Common Errors

1. Confusing diagonal with width. A '55-inch' TV is 139.7 cm diagonally — not in width. The actual width of a 55-inch 16:9 TV is about 121.8 cm. Your TV stand needs at least 125–127 cm of clearance.

2. Measuring bezel-to-bezel instead of screen-to-screen. The advertised size is the active display area only. The physical chassis adds 2–5 cm per side.

3. Using an approximate factor. The exact factor is 2.54, not 2.53 or 2.55. Over a 75-inch screen, using 2.55 introduces a 0.75 cm error — enough to matter for tight installations.

4. Assuming advertised size equals exact size. A '55-inch' TV may actually measure 54.5 inches diagonally — manufacturers use nominal class labels. Always check the spec sheet for exact viewable diagonal when precision matters.

5. Applying 16:9 formulas to phones. Modern smartphones use 20:9 or 19.5:9 aspect ratios. A 6.1-inch phone is narrower than a 6.1-inch 16:9 device would be.

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55-inch TV → centimeters

Enter 55 in the screen size field and select 'Inches to Centimeters'.

The formula applies: 55 × 2.54 = 139.70 cm.

The 'Converted Result' field shows 139.7 cm (this is the diagonal of the TV).

For a 16:9 TV: width ≈ 139.7 × 0.872 = 121.8 cm; height ≈ 139.7 × 0.490 = 68.5 cm.

55 in = 139.7 cm diagonal

Frequently asked questions

Why is 1 inch exactly 2.54 centimeters?

The 1959 International Yard and Pound Agreement, adopted by the US, UK, Canada, Australia, and others, defined the international inch as exactly 2.54 cm. NIST confirms this as an exact, invariant definition — not a measured or rounded value. There is zero rounding error in this conversion.

How many cm is 55 inches (TV size)?

55 × 2.54 = 139.70 cm diagonal. For a 16:9 TV: width ≈ 121.8 cm, height ≈ 68.5 cm. Your TV unit should be at least 125–127 cm wide to accommodate the physical frame.

How many cm is 65 inches?

65 × 2.54 = 165.10 cm diagonal. Width of a 16:9 65-inch TV ≈ 143.9 cm; height ≈ 81 cm. The physical chassis adds 3–5 cm per side.

Is screen size always measured diagonally?

Yes. The consumer electronics industry universally measures display size as the diagonal of the active screen area, following convention established in the early CRT television era. Width and height are not used for the advertised size. For a 16:9 aspect ratio, width ≈ diagonal × 0.872 and height ≈ diagonal × 0.490.

How do I convert cm back to inches for screen size?

Divide by 2.54: inches = cm ÷ 2.54. Example: a European retailer lists a TV as 164 cm → 164 ÷ 2.54 = 64.57 inches, which rounds to the 65-inch class. A 139 cm TV = 139 ÷ 2.54 = 54.72 inches, which is the 55-inch class.

Why do European retailers list TV sizes in cm while US retailers use inches?

The metric system is the official measurement standard throughout the European Union (mandated by EU Directive 80/181/EEC), so consumer products are labeled in centimeters. The US predominantly uses the US customary system, where inches are conventional for screen sizes. Both values describe the same diagonal; only the unit differs.

What is PPI and how does screen size in inches affect it?

PPI = √(horizontal_pixels² + vertical_pixels²) ÷ diagonal_inches. For a 27-inch 1920×1080 monitor: √(1920²+1080²) = 2202.9 pixels ÷ 27 = 81.6 PPI. The same resolution on a 24-inch screen = 91.8 PPI — sharper because the same pixels are packed into a smaller area.

Does the bezel affect the advertised screen size?

No. The advertised screen size refers only to the active display area (the lit panel), measured diagonally corner to corner. The bezel adds several centimeters to the physical device footprint but is never included in the screen size specification. A 27-inch (68.58 cm) monitor's full chassis width is typically 63–65 cm.

Are there any screens where the nominal size doesn't match the actual diagonal?

Yes — manufacturers use 'size class' labeling, where a '55-inch TV' may actually measure 54.5 to 54.9 inches diagonally. The FTC does not require exact match between the label and measured diagonal as long as the specification sheet discloses the actual viewable size. Always check the product spec sheet's 'viewable area' field for precise measurements when installation clearance is critical.

Sources & references

Methodology & trust

Editorial

Calculadora de matemática revisada por el equipo editorial de Hacé Cuentas, contrastada con NIST – Unit of Length: The Inch (International), según nuestra política editorial y metodología.

Updates

Última revisión: June 16, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). Convert Inches to Centimeters — TV, Monitor & Phone Screen Sizes. Hacé Cuentas. https://hacecuentas.com/inches-to-cm-screen-converter

Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.

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