Aspect Ratio Cheat Sheet
An aspect ratio is the proportional relationship between an image's width and height — 1:1 is square, 4:5 is portrait, 9:16 is vertical, 16:9 is widescreen landscape.
The seven ratios below cover every image size used across the major social, ad, web, email, and print platforms. Each row shows what the ratio looks like, one representative pixel size, and where it's used.
The seven ratios that cover everything
| Ratio | Shape | Example | Used for |
|---|---|---|---|
| 1:1 | Square | 1080 × 1080 | |
| 4:5 | Portrait | 1080 × 1350 | |
| 2:3 | Tall portrait | 1000 × 1500 | |
| 3:4 | Portrait | 1080 × 1440 | |
| 9:16 | Full-screen vertical | 1080 × 1920 | |
| 16:9 | Widescreen landscape | 1920 × 1080 | |
| 1.91:1 | Landscape (Open Graph) | 1200 × 630 |
How to calculate aspect ratio from pixel dimensions
- Divide the width in pixels by the height in pixels.
- The result is the ratio expressed as a decimal — 1.777 for 16:9, 0.5625 for 9:16, 1.0 for 1:1.
- To express as width:height, find the greatest common divisor and divide both. 1920 and 1080 share a GCD of 120 → 16:9.
Frequently asked questions
What is an aspect ratio?
An aspect ratio is the proportional relationship between an image's width and height, expressed as width:height. A 1:1 image is square; a 16:9 image is widescreen; a 9:16 image is vertical.
How do I calculate aspect ratio from pixel dimensions?
Divide the width by the height, then simplify. A 1920 × 1080 image is 1920 ÷ 1080 = 1.777…, which is the 16:9 ratio. To simplify manually, find the greatest common divisor of the two dimensions.
What's the difference between 4:5 and 3:4?
Both are portrait ratios, but 4:5 is taller relative to its width than 3:4. A 4:5 image at 1080 wide is 1350 tall; a 3:4 image at 1080 wide is 1440 tall. Instagram uses 4:5 for its portrait post size.
Which aspect ratio is best for social media?
It depends on the platform. Instagram and Facebook prefer 4:5 (portrait) for reach; TikTok, Stories and Reels are 9:16 (vertical); YouTube is 16:9 (landscape); Pinterest is 2:3 (portrait).
Does aspect ratio affect image quality?
No — aspect ratio only describes shape. Quality is controlled by pixel dimensions and compression. However, uploading the wrong ratio to a platform forces a crop, which effectively removes part of the image.
Can I convert an image from one aspect ratio to another?
Yes, by either cropping (removes content) or padding (adds bars). Both change what the viewer sees — there is no way to change ratio without losing content or adding empty space.