Aspect Ratio Explained (16:9, 4:3, 1:1 and More)

Aspect ratio is the proportion of an image's width to its height, written as two numbers like 16:9. It describes shape, not size — a 1600×900 and an 800×450 image share the 16:9 ratio.

Common ratios and where they appear

• 16:9 — widescreen video, YouTube, most monitors and phones
• 4:3 — older screens, many cameras and presentations
• 1:1 — square, used for profile pictures and many social posts
• 9:16 — vertical video for Stories and Reels

Why keep the ratio

If you resize width and height by different amounts, the image stretches — faces widen, circles turn oval. Locking the aspect ratio scales both dimensions together so the picture stays undistorted.

Fitting a different ratio

To place an image in a frame of another ratio, either crop it to the target shape or add padding (letterboxing). Stretching should be a last resort.

Resize correctly

Change dimensions while keeping proportions with the image resizer. Related: How to resize an image.