What is aspect ratio?

Aspect ratio is the proportional relationship between width and height, expressed as width:height. A 16:9 ratio means for every 16 units of width, there are 9 units of height.

What is the most common aspect ratio for video?

16:9 (1.78:1) is the standard widescreen ratio used for HDTV, YouTube, and most modern video content. 4:3 was standard for older TV and photography.

How do I maintain aspect ratio when resizing?

If the original is W×H and you want to resize to a new width W2, calculate new height as H2 = H × (W2/W). This calculator does that math automatically.

What aspect ratio should I use for Instagram?

1:1 (square) is the original Instagram format. 4:5 portrait (1080×1350) shows more of your image. 1.91:1 landscape works for feed posts. Stories use 9:16.

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Aspect Ratio Calculator

Calculate image and video aspect ratios — find dimensions for any ratio, scale images proportionally.

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About this tool

Calculate dimensions that maintain a specific aspect ratio. Enter width and height to get the ratio (16:9, 4:3, etc.), or enter a ratio and one dimension to calculate the other. Includes preset ratios for common screen sizes, social media, and video formats.

How to use

1 Enter width and height to calculate the aspect ratio.
2 Or select a preset ratio (16:9, 4:3, etc.) and enter one dimension.
3 The missing dimension is calculated automatically.
4 Use the Ratio display to verify the simplified ratio.

Frequently Asked Questions

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