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Aspect Ratio Calculator

Calculate aspect ratios, resize images proportionally, and find the right dimensions for any platform.

Quick Presets

Enter Dimensions

Width

Height

Aspect Ratio

16:9

Decimal

1.7778

Megapixels

2.07 MP

Visual Preview

16:9

1920 x 1080 px

Resize Proportionally

Enter a new width or height and the other dimension will be calculated to maintain the 16:9 aspect ratio.

New Width

New Height

Common Resolutions

When Aspect Ratio Matters

Video editing — use 16:9 for YouTube, 9:16 for TikTok/Reels, 1:1 for square posts
Photography — 3:2 for DSLR, 4:3 for phones, 1:1 for Instagram
Web design — maintain ratios when resizing images to avoid distortion
Print — match your canvas ratio to the paper size for full-bleed printing
Social media — each platform has preferred sizes; wrong ratios get cropped

About Aspect Ratio Calculator

Free aspect ratio calculator that determines the aspect ratio of any width and height, lets you resize proportionally while maintaining the ratio, and provides instant presets for YouTube (16:9), Instagram (1:1, 4:5), TikTok (9:16), and more. Enter pixel dimensions to see the simplified ratio, decimal value, and megapixel count. Use the proportional resize tool to scale images without distortion. Includes a visual preview and a reference table of common screen resolutions and social media sizes. Essential for video editors, photographers, designers, and content creators.

Frequently Asked Questions

How is aspect ratio calculated?▾

Aspect ratio is calculated by dividing both the width and height by their greatest common divisor (GCD). For example, 1920÷120 = 16 and 1080÷120 = 9, giving a 16:9 ratio. This tool does the math automatically — just enter any width and height to get the simplified ratio.

What aspect ratio should I use for YouTube?▾

YouTube videos use 16:9 (1920×1080 for Full HD, 3840×2160 for 4K). YouTube Shorts use 9:16 (1080×1920). Thumbnails are also 16:9 at 1280×720 pixels. Using the wrong ratio causes black bars or cropping.

What ratio does Instagram use?▾

Instagram supports multiple ratios: 1:1 (1080×1080) for square posts, 4:5 (1080×1350) for portrait posts (gets the most screen space in the feed), and 9:16 (1080×1920) for Stories and Reels. Profile pictures are displayed as 1:1 circles.

How do I resize without distortion?▾

To resize without distortion, you must maintain the same aspect ratio. Use the 'Resize Proportionally' section: enter a new width and the height is automatically calculated (or vice versa) to maintain the current ratio. This prevents the image from looking stretched or squished.

What does megapixels mean?▾

Megapixels (MP) is the total number of pixels in an image, calculated as width × height ÷ 1,000,000. For example, 1920×1080 = 2.07 MP. Higher megapixels mean more detail, but also larger file sizes. A 12 MP smartphone camera produces 4000×3000 pixel images.