How It Works
An aspect ratio describes the proportional relationship between width and height. The calculator uses the Greatest Common Divisor (GCD) algorithm to simplify dimensions to their smallest whole-number ratio.
For example, 1920 and 1080 share a GCD of 120. Dividing both by 120 gives 16 and 9 — so the ratio is 16:9. The algorithm works by repeatedly dividing the larger number by the smaller until the remainder is zero. The last non-zero remainder is the GCD.
In the ratio-to-dimensions modes, the tool uses simple cross-multiplication. If you want a 16:9 image that is 1280px wide, the height is 1280 × 9 / 16 = 720px.
Common Aspect Ratios
| Ratio | Decimal | Common Use |
|---|---|---|
| 16:9 | 1.7778 | YouTube, TV, most video content, desktop wallpapers |
| 1:1 | 1.0000 | Instagram posts, profile pictures, album art |
| 9:16 | 0.5625 | Instagram Stories, TikTok, YouTube Shorts, Reels |
| 4:3 | 1.3333 | Classic TV, iPad, presentations, older monitors |
| 3:2 | 1.5000 | DSLR photos, 35mm film, MacBook displays |
| 2:3 | 0.6667 | Pinterest pins, portrait photography, book covers |
| 21:9 | 2.3333 | Ultrawide monitors, cinematic video |
| ~1.91:1 | 1.9048 | Facebook and LinkedIn link previews |
| 5:4 | 1.2500 | 8×10 prints, some older monitors |
| 2.39:1 | 2.3900 | Anamorphic widescreen cinema |
Social Media Image Sizes
| Platform | Dimensions | Ratio | Use Case |
|---|---|---|---|
| YouTube | 1920×1080 | 16:9 | Video upload, thumbnail |
| YouTube Shorts | 1080×1920 | 9:16 | Short-form vertical video |
| Instagram Post | 1080×1080 | 1:1 | Feed post (square) |
| Instagram Story | 1080×1920 | 9:16 | Story, Reel |
| TikTok | 1080×1920 | 9:16 | Video upload |
| Twitter / X Post | 1600×900 | 16:9 | Shared image |
| Facebook Post | 1200×630 | ~1.91:1 | Link preview, shared image |
| LinkedIn Post | 1200×627 | ~1.91:1 | Link preview, shared image |
| Pinterest Pin | 1000×1500 | 2:3 | Standard pin |
| Standard Photo | 3000×2000 | 3:2 | DSLR landscape photo |
FAQ
What aspect ratio is 1920x1080?
1920×1080 has an aspect ratio of 16:9. This is the standard widescreen ratio used by YouTube, most TVs, and computer monitors. The GCD of 1920 and 1080 is 120, so 1920/120 = 16 and 1080/120 = 9.
What is the best aspect ratio for social media?
It depends on the platform. For feed posts on Instagram, use 1:1(1080×1080). For Stories, Reels, TikTok, and YouTube Shorts, use 9:16(1080×1920). For YouTube videos and Twitter images, use 16:9. For Pinterest, use 2:3(1000×1500).
How do I resize an image without cropping?
You have two options. First, add padding (letterboxing or pillarboxing) to fill the extra space without losing content. Second, use the same aspect ratio as the original when resizing — the calculator above helps you find dimensions that maintain the ratio. If your source is 4:3 and you need 16:9, cropping or padding is unavoidable.
What aspect ratio is widescreen?
The standard widescreen ratio is 16:9 (1.78:1). Ultra- widescreen monitors use 21:9 (2.33:1). Cinematic widescreen is typically 2.39:1. The older fullscreen ratio is 4:3 (1.33:1), which you may still see on legacy content and some tablets.
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