Aspect Ratio Calculator

Aspect Ratio Calculator

Calculate simplest integer and decimal aspect ratios, resize image and video dimensions proportionally without distortion, and compute physical screen sizes from diagonal.

Original Dimensions
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px
100 px HD: 1920 px 4000 px
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px
100 px FHD: 1080 px 3000 px
Proportional Resizer (Target Dimensions) Ratio Locked 🔒
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100 px Scale target 4000 px
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px
100 px Scale target 3000 px
aspect-ratio: 16 / 9;
Aspect Ratio Result 16:9 Standard
16:9
Decimal Ratio: 1.78:1 · Landscape · Full HD (1080p)
Dimensions & Scaling Breakdown GCD: 120
Simplest Integer Ratio 16:9
Decimal Ratio (Width / Height) 1.78:1 (1.7778)
Inverse Ratio (Height / Width) 0.5625:1 (9:16)
Original Resolution 1920 × 1080 px (2.07 MP)
Original Diagonal Length 2,202.9 px
Resized Target Dimensions 1280 × 720 px (0.92 MP)
Proportional Scale Factor 66.67% (-33.33% size)
CSS Padding-Top Hack 56.25%
Aspect Ratio Viewport
1920 px 1080 px 16:9 D: 2,203 px
Active Box: 1920 × 1080 (16:9)
Target: 1280 × 720 (66.7%)
Screen Specs (Diagonal & Ratio)
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in
10 in (Tablet) 55 in (Living Room) 100 in (Projector)
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Why Diagonal Matters

A 55-inch 16:9 TV has 1,293 sq in of display area, whereas a 55-inch 21:9 ultrawide has only 1,061 sq in—nearly 18% less total screen real estate!

Physical Screen Dimensions 55" 16:9 Display
47.9" × 27.0"
121.8 cm × 68.5 cm · Area: 1,293.5 sq in (0.83 m²)
Physical Display Metrics
Physical Screen Width 47.94 in (121.76 cm)
Physical Screen Height 26.96 in (68.49 cm)
Screen Surface Area 1,292.5 sq in (8,339 cm² / 0.83 m²)
Selected Aspect Ratio 16:9 (1.78:1)
Screen Diagonal 55.0 in (139.7 cm)

Standard Aspect Ratios & Resolution Directory

Common aspect ratios used across modern cinema, broadcasting, photography, monitors, and social media platforms:

Ratio (W:H) Decimal Common Resolutions Primary Use Cases
16:9 1.78:1 1920×1080 (FHD), 3840×2160 (4K), 1280×720 (HD) Universal standard for HDTV, YouTube, computer monitors, gaming.
9:16 0.56:1 1080×1920, 720×1280, 2160×3840 Vertical video for TikTok, Instagram Reels, YouTube Shorts, Snapchat.
1:1 1.00:1 1080×1080, 2048×2048, 500×500 Instagram grid photos, product carousels, profile avatars.
4:5 0.80:1 1080×1350 Instagram portrait feed posts (maximizes vertical mobile screen space).
4:3 1.33:1 1024×768, 1440×1080, 2048×1536 Classic standard-definition TV, Apple iPad tablets, Micro 4/3 photography.
21:9 2.37:1 2560×1080, 3440×1440, 5120×2160 Ultrawide gaming and productivity monitors, modern theatrical films.
32:9 3.56:1 5120×1440 (Dual QHD), 3840×1080 Super ultrawide curved gaming monitors (equivalent to dual 16:9 screens).
16:10 1.60:1 1920×1200, 2560×1600, 2880×1800 Apple MacBooks, high-productivity office monitors, Android tablets.
3:2 1.50:1 6000×4000, 3000×2000, 2160×1440 35mm film, standard DSLR / mirrorless camera sensors, Microsoft Surface.
2.39:1 2.39:1 2048×858 (2K Scope), 4096×1716 (4K Scope) Anamorphic widescreen cinema (CinemaScope / Panavision).

Aspect Ratio & Resizing Mathematical Formulas

An aspect ratio represents the proportional relationship between width (W) and height (H). It is expressed in reduced whole numbers using the Euclidean Greatest Common Divisor (gcd).

1. Integer Ratio Reduction (Euclidean Algorithm)
g = gcd(W, H) Simplest Ratio = (W / g) : (H / g) Decimal Ratio = W / H : 1

Live Example: gcd(1920, 1080) = 120 → (1920/120) : (1080/120) = 16:9

2. Proportional Resizing (Cross-Multiplication)
New Height (H₂) = W₂ × (H₁ / W₁) New Width (W₂) = H₂ × (W₁ / H₁) Diagonal = √(W² + H²)

Live Example: H₂ = 1280 × (1080 / 1920) = 1280 × 0.5625 = 720 px

Mastering Aspect Ratios in Digital Media

Whether you are editing video for YouTube, formatting vertical reels for social platforms, coding responsive web elements, or purchasing a home theater display, maintaining the correct aspect ratio is essential to prevent awkward letterboxing (black bars on top and bottom), pillarboxing (black bars on left and right), or unnatural image stretching.

Letterboxing vs. Pillarboxing

• Letterboxing: Horizontal black bars appear above and below widescreen content when displayed on a narrower screen (e.g., viewing a 2.39:1 movie on a 16:9 TV).
• Pillarboxing: Vertical black bars appear on the left and right when narrower content is shown on a wider screen (e.g., playing a 4:3 vintage video on a 16:9 monitor).

Modern CSS aspect-ratio Property

Modern web design natively supports the CSS aspect-ratio: 16 / 9; declaration. This replaces legacy percentage padding hacks (padding-top: 56.25%) and prevents Cumulative Layout Shift (CLS) during image and iframe rendering.

Frequently Asked Questions

What is the difference between aspect ratio and resolution?
Aspect ratio is the proportional ratio of width to height (e.g., 16:9), regardless of the actual size. Resolution is the exact physical count of pixels that comprise the image (e.g., 1920×1080 or 3840×2160). Both 1080p and 4K have identical 16:9 aspect ratios, but 4K contains four times as many pixels.
How do I resize an image without distorting or stretching it?
To resize without distortion, maintain the original aspect ratio constant. Divide the new width by the original width to determine the scale factor, then multiply the original height by this exact same factor. Alternatively, enter your desired width into this calculator, and the target height is instantly calculated.
Why does 1366×768 simplify to 683:384 instead of 16:9?
1366 and 768 are only divisible by 2, yielding 683:384 mathematically. However, 1366 / 768 is 1.7786, which is within 0.05% of the exact 16:9 ratio (1.7778). Hardware manufacturers designed 1366×768 laptop panels as a manufacturing optimization while targeting the 16:9 standard.
What is the best aspect ratio for social media?
The ideal aspect ratio depends on the platform: use 9:16 (1080×1920) for full-screen vertical content (TikTok, Instagram Reels, YouTube Shorts); 4:5 (1080×1350) for Instagram portrait feed posts; 1:1 (1080×1080) for square posts; and 16:9 (1920×1080) for standard YouTube videos and horizontal desktop feeds.
How do you calculate physical screen dimensions from the diagonal?
Using the Pythagorean theorem, for a screen with diagonal D and aspect ratio W:H, Width = D × W / √(W² + H²) and Height = D × H / √(W² + H²). For a 55-inch 16:9 display, Width = 55 × 16 / √(256 + 81) = 47.94 inches, and Height = 55 × 9 / √337 = 26.96 inches.