What is Aspect Ratio Calculator?
Aspect ratio calculator for computing and verifying image, video, and screen proportions. Common presets: 16:9 (HD video), 4:3 (traditional TV), 1:1 (social media square), 21:9 (ultrawide), 9:16 (vertical video). Enter either width or height and the other dimension is calculated automatically. Perfect for video editing, image cropping, responsive design, and print size calculation. All computation runs locally in your browser.
Use Cases
- ◆Video editing resolution setup
- ◆Image cropping ratio control
- ◆Responsive web design
- ◆Print size calculation
- ◆Screen ratio verification
How to Use
- 1Pick a preset ratio or enter custom values
- 2Enter width or height
- 3Other dimension auto-calculates
- 4See the result
Features
- ✓Common presets
- ✓Custom ratios
- ✓Proportional scaling
- ✓Real-time calculation
- ✓Integer/decimal toggle
FAQ
What is the difference between 16:9 and 4:3?
16:9 is widescreen (1.78:1) — used for HD video (1920×1080, 3840×2160). 4:3 is traditional (1.33:1) — used for old TVs and iPads. 16:9 is wider, better for movies and video.
How do I calculate the aspect ratio of 1920×1080?
1920 ÷ 1080 = 1.778 ≈ 16/9. Divide both by the GCD: GCD(1920,1080)=120, so 1920÷120=16, 1080÷120=9. Ratio is 16:9.
What is 21:9 used for?
21:9 (2.39:1) is the cinematic widescreen ratio for theatrical video. Also common on ultrawide monitors (3440×1440). Great for film editing and multi-window workflows.
What aspect ratio does Instagram recommend?
Square posts: 1:1 (1080×1080). Portrait posts: 4:5 (1080×1350). Stories/Reels: 9:16 (1080×1920). Landscape posts: 1.91:1 (1080×566).
Does flipping width and height change the ratio?
Yes. 16:9 flipped becomes 9:16. 16:9 is landscape, 9:16 is portrait. Phone video typically uses 9:16.
How do I calculate scaled dimensions?
Keep the ratio: new width = original width × (new height / original height). E.g., 1920×1080 scaled to height 720: new width = 1920 × (720/1080) = 1280. Result: 1280×720.