Aspect Ratio Calculator
Find the aspect ratio from width and height, or derive missing pixel dimensions from a ratio. Includes 16:9, 4:3, 21:9, and more.
Width / height or ratio
Aspect ratio
16:9
Dimensions: 1920 x 1080 px
Frequently Asked Questions about the Aspect Ratio Calculator
What is an aspect ratio?
The proportional relationship between width and height. A 16:9 image is 16 units wide for every 9 units tall. The ratio stays constant regardless of pixel dimensions.
Which aspect ratio should I use for video?
16:9 is the standard for YouTube, TV, and most monitors. Use 9:16 for vertical mobile content (Reels, Shorts, TikTok), 1:1 for Instagram feed posts, and 21:9 for cinematic ultrawide footage.
How do I resize an image without distortion?
Enter the original width and height to read the ratio, then enter your new width. The calculator returns the matching height that preserves the original proportions.
What aspect ratio is best for photography?
3:2 matches most DSLR and mirrorless sensors and standard photo prints. 4:3 matches Micro Four Thirds cameras and older point-and-shoots. 1:1 works well for social posts and album covers.
Why is my ratio simplified to odd numbers?
The calculator divides width and height by their greatest common divisor. A 1920x1080 image simplifies to 16:9, but 1366x768 simplifies to 683:384 since it is not exactly 16:9.