Aspect Ratio Calculator
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Aspect Ratio
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16:9
Ratio
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Common Name
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Width
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Height
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Decimal Ratio
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Diagonal (same units)
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Common Aspect Ratios
16:9 — HD video, YouTube, monitors | 4:3 — older TVs, presentations | 1:1 — Instagram posts | 9:16 — TikTok, Reels, Stories | 4:5 — Instagram portrait | 3:2 — DSLR photos | 21:9 — ultrawide cinema
How Ratios Are Simplified
Divide both numbers by their greatest common divisor (GCD). 1920 × 1080 → GCD is 120 → 16:9. 1280 × 960 → GCD is 320 → 4:3. If the ratio has decimals, it cannot be simplified to whole numbers (e.g., 2.35:1).
Why It Matters for Creators
Using the wrong aspect ratio causes black bars (letterboxing), cropping, or stretched content. Always export video and images at the native aspect ratio of your target platform before resizing.