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Direct answer
The UseCOS Aspect Ratio Calculator computes the simplified proportional ratio between width and height using the Euclidean Greatest Common Divisor (GCD) algorithm, and allows real-time proportional scaling for video (16:9, 21:9), vertical social content (9:16, 4:5), and photography (3:2, 4:3).
Find the exact aspect ratio from pixel dimensions or resize width and height with a locked ratio.
16:9 is standard for modern monitors, YouTube videos, and TV screens (1080p, 4K). 21:9 is ultrawide cinema format.
9:16 vertical format powers TikTok, Instagram Reels, and YouTube Shorts. 1:1 and 4:5 are standard feed posts.
3:2 is the native sensor ratio of 35mm DSLR and mirrorless cameras. 4:3 is standard on Micro Four Thirds and medium formats.
An aspect ratio represents the proportional relationship between the width and height of an image, video frame, or display screen. Rather than describing absolute size in inches or pixels, it defines the shape of the rectangle.
| Aspect Ratio | Decimal | Common Dimensions | Typical Uses |
|---|---|---|---|
| 16:9 | 1.777:1 | 1920×1080, 3840×2160 | YouTube videos, HD/4K TV, PC Monitors |
| 9:16 | 0.562:1 | 1080×1920, 720×1280 | TikTok, Instagram Reels, YouTube Shorts, Stories |
| 1:1 | 1.000:1 | 1080×1080, 500×500 | Instagram Square, Profile Avatars, App Icons |
| 4:3 | 1.333:1 | 1024×768, 1600×1200 | Classic SD TV, iPad screens, Micro Four Thirds |
| 21:9 | 2.333:1 | 2560×1080, 3440×1440 | Ultrawide Gaming Monitors, Cinematic Widescreen |
| 3:2 | 1.500:1 | 6000×4000, 3000×2000 | Full-frame 35mm DSLR & Mirrorless Photography |
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