Aspect Ratio Calculator
Calculate aspect ratios from pixel dimensions, or find the right dimensions for any ratio. Free, instant, with a visual preview.
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What Is an Aspect Ratio?
An aspect ratio describes the proportional relationship between the width and height of an image or screen. It's expressed as two numbers separated by a colon, like 16:9 or 4:3. The first number represents the width, and the second represents the height.
Aspect ratios are essential for video production, photography, web design, and social media content creation. Using the correct aspect ratio ensures your content displays properly without unwanted cropping or black bars.
Common Aspect Ratios
| Ratio | Decimal | Common Use | Example Resolution |
|---|---|---|---|
| 16:9 | 1.778 | HD video, YouTube, TV | 1920 x 1080 |
| 4:3 | 1.333 | Standard TV, presentations | 1024 x 768 |
| 3:2 | 1.500 | DSLR photography | 1080 x 720 |
| 1:1 | 1.000 | Instagram post, square | 1080 x 1080 |
| 21:9 | 2.333 | Ultrawide monitors, cinema | 2560 x 1080 |
| 9:16 | 0.563 | Stories, TikTok, Reels | 1080 x 1920 |
| 4:5 | 0.800 | Instagram portrait | 1080 x 1350 |
| 2.39:1 | 2.390 | Anamorphic cinema | 2048 x 858 |
How to Calculate Aspect Ratio
To find the aspect ratio of an image or screen, divide both the width and height by their greatest common divisor (GCD). For example, a 1920 x 1080 display: the GCD of 1920 and 1080 is 120, so 1920/120 = 16 and 1080/120 = 9, giving a 16:9 aspect ratio.
To calculate dimensions from a known ratio, multiply the ratio by a scaling factor. If you need a 16:9 image that is 1280 pixels wide: 1280 / 16 = 80, then 80 x 9 = 720. The result is 1280 x 720.