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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.
Production reference specifications (2026) for video streaming, vertical short-form, mobile feeds, and social OpenGraph tags.
| Ratio & Decimal | Standard Resolution | Primary Channels | Safe-Zone & Cropping Guardrails |
|---|---|---|---|
| 16:9 (1.778:1) | 1920×1080 (FHD) 3840×2160 (4K) | YouTube Long-Form, TV, PC Monitors, Twitch | Industry master video standard. Keep text and essential graphics within central 80% to avoid edge overscan. |
| 9:16 (0.562:1) | 1080×1920 (FHD) 720×1280 (HD) | TikTok, Instagram Reels, YouTube Shorts, Stories | Strict safe zone: Keep critical text out of top 15% (header UI) and bottom 20% (caption, audio, and CTA buttons). |
| 4:5 (0.800:1) | 1080×1350 | Instagram Feed Portrait, Facebook Mobile | Captures maximum vertical mobile feed screen estate without black bars. Profile grid crops central 1:1 square. |
| 1:1 (1.000:1) | 1080×1080 | Instagram Square, E-Commerce Product, Avatars | Zero crop risk on grid layouts. Universal thumbnail format for products and carousels. |
| 1.91:1 (1.910:1) | 1200×630 | LinkedIn Link Preview, Twitter/X Card, OpenGraph | Strict meta tag preview ratio. Images with smaller dimensions or different ratios get letterboxed or centered-cropped. |
| 21:9 (2.333:1) | 2560×1080 3440×1440 | Ultrawide Monitors, Cinematic 2.39:1 Anamorphic | Widescreen cinematic immersion. Standard 16:9 displays will pillarbox with black bars on left/right. |
| 3:2 (1.500:1) | 6000×4000 3000×2000 | DSLR Photography, 4×6 Prints, Surface Laptop | Golden ratio of 35mm film photography. Direct fit for classic 4×6 photo lab prints without cropping. |
| 4:3 (1.333:1) | 2048×1536 1024×768 | Apple iPad Retina, Micro 4/3 Cameras, Classic TV | Optimal reading and document viewing ratio. Standard camera sensor aspect ratio for smartphones (raw sensor). |
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