ganak.appScreen Size Calculator
Calculate the physical width, height, and area of any screen from its diagonal size and aspect ratio. Add resolution for PPI, dot pitch, and megapixel count. Auto-detect your screen resolution, get SMPTE and THX viewing distance recommendations, and check Retina quality. Supports all aspect ratios including 16:9, 21:9, 4:3, and custom.
Physical Dimensions
Width, height, diagonal, and viewable area of your screen
23.53 inches
59.8 cm
13.24 inches
33.6 cm
27.00 inches
68.6 cm
311.5 sq in
2010 sq cm
Pixel Density
PPI, dot pitch, resolution, and Retina assessment for your display
Pixels Per Inch
109
PPI
Dot Pitch
0.233
mm
Resolution
2560x1440
Megapixels
3.7
3,686,400 px
Recommended Viewing Distance
SMPTE and THX industry standards based on your screen width
SMPTE Standard
30° viewing angle
3 ft 8 in
112 cm
THX Immersive
36° viewing angle
3 ft 0 in
92 cm
THX Back Row
26° viewing angle
4 ft 3 in
129 cm
SMPTE recommends 30° for home theater. THX standards range from 26° (back row) to 36° (immersive).
What Is Screen Size?
Understanding diagonal measurement and physical dimensions
Screen size refers to the diagonal measurement of a display, measured from one corner to the opposite corner. While the diagonal is the standard way screens are marketed, the actual width and height depend on the screen's aspect ratio.
Two screens with the same diagonal but different aspect ratios will have different physical dimensions. For example, a 27-inch 16:9 monitor is 23.53 x 13.24 inches, while a 27-inch 16:10 monitor is 22.90 x 14.31 inches — narrower but taller.
16:9
Widescreen
TVs, monitors, laptops
21:9
Ultrawide
Gaming & productivity
4:3
Standard
Classic & iPads
How Are Screen Dimensions Calculated?
The Pythagorean theorem relates the diagonal, width, and height. Combined with the aspect ratio, we can derive exact physical dimensions from just the diagonal measurement.
Example — 27" 16:9 Display
Width
23.53"
27 × 16/√(16²+9²)
Height
13.24"
27 × 9/√(16²+9²)
Area
311.5 sq in
23.53 × 13.24
How to Use This Calculator
Follow these steps to find your screen dimensions
1. Enter Diagonal
Type the diagonal measurement in inches or centimeters. This is the number advertised for your TV, monitor, or laptop.
2. Pick Aspect Ratio
Select from 11 presets (16:9, 21:9, 4:3, etc.) or enter a custom ratio. The calculator filters matching resolutions automatically.
3. Read Dimensions
Instantly see physical width, height, area, and orientation. Toggle between inches and centimeters with one click.
4. Add Resolution (Optional)
Select a resolution to unlock PPI, dot pitch, megapixels, Retina assessment, and viewing distance recommendations.
Common Screen Sizes at a Glance
Popular diagonal sizes and their physical dimensions (16:9 aspect ratio)
| Diagonal | Width | Height | Area |
|---|---|---|---|
| 24" | 20.92" | 11.77" | 246.1 sq in |
| 27" | 23.53" | 13.24" | 311.5 sq in |
| 32" | 27.89" | 15.69" | 437.5 sq in |
| 40" | 34.86" | 19.61" | 683.6 sq in |
| 43" | 37.48" | 21.08" | 790.3 sq in |
| 50" | 43.58" | 24.51" | 1068.2 sq in |
| 55" | 47.94" | 26.96" | 1292.4 sq in |
| 65" | 56.65" | 31.87" | 1804.8 sq in |
| 75" | 65.37" | 36.77" | 2403.7 sq in |
| 85" | 74.09" | 41.67" | 3087.0 sq in |
Viewing Distance Explained
Optimal viewing distance depends on screen size and resolution. Sitting too close causes eye strain, while sitting too far reduces immersion. Industry standards provide guidelines:
SMPTE (30°)
The Society of Motion Picture and Television Engineers recommends a 30° horizontal viewing angle. This is the most widely cited home theater standard.
THX Immersive (36°)
THX recommends a 36° viewing angle for an immersive cinema-like experience at home. This puts you closer to the screen.
THX Back Row (26°)
The minimum acceptable viewing angle per THX standards. Beyond this distance, the screen may feel too small.
About Screen Size Calculator
How screen dimensions are calculated from diagonal and aspect ratio
A screen size calculator converts the diagonal measurement of a display into its actual physical width, height, and viewable area. Since screens are marketed by diagonal size, the real dimensions depend on the aspect ratio. This tool uses the Pythagorean theorem to compute exact dimensions, and optionally calculates pixel density (PPI), dot pitch, and recommended viewing distances using SMPTE and THX industry standards. It also supports auto-detecting your screen resolution.
Frequently Asked Questions
Common questions about screen size, dimensions, and display specifications