Aspect Ratios Explained: 16:9, 4:3, 1:1 and Resizing

An aspect ratio is the relationship between an image's width and its height. A ratio of 16:9 means that for every 16 units of width, there are 9 units of height. It describes the shape, not the size, so a tiny and a huge picture can share the same ratio.

Common ratios and where they are used

• 16:9: widescreen video, YouTube, most monitors and TVs. For example, 1920 by 1080 or 1280 by 720.
• 4:3: older TVs and monitors, and many tablets and compact cameras. For example, 1024 by 768.
• 3:2: most digital SLR photos and 35 mm film.
• 1:1: square posts and profile pictures.
• 9:16: vertical video for stories and short clips.
• 21:9: ultrawide monitors and cinema-style video.

How to resize without stretching

Pick the new width, then work out the height using the ratio:

new height = new width * (old height / old width)

Example: 1920x1080 resized to 1280 wide
1280 * (1080 / 1920) = 720

If you set both the width and the height yourself and they don't match the ratio, the picture will look squashed or stretched. The Aspect Ratio Calculator does this maths for you, and the Image Resizer keeps the ratio locked while you change the size.

When you need a different ratio

Changing the shape means cropping, which removes part of the picture. Decide what matters most, then crop around it. The Image Cropper has presets for common ratios and lets you drag the box to choose what stays in the frame.

Tips

• Check the platform's recommended size before you export. Each network crops differently.
• Keep important content near the center, so a different crop doesn't cut it off.
• Start from the largest original you have. Cropping and then enlarging makes images blurry.