Aspect Ratio Calculator
Calculate aspect ratios, scale image dimensions proportionally, and find missing width or height values.
Results are for general guidance only — not professional advice. Learn more.
How to use this tool
Choose a mode depending on what you need to calculate:
- Scale Dimensions: Enter an original width and height, then enter either a new width or new height — the other dimension is calculated automatically to maintain the aspect ratio.
- Find Ratio: Enter any width and height in pixels to find the simplified aspect ratio, its common name (e.g. 16:9 Widescreen), and the megapixel count.
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Frequently asked questions
What is an aspect ratio?
An aspect ratio is the proportional relationship between the width and height of an image, screen, or frame. It is usually expressed as two numbers separated by a colon, such as 16:9 or 4:3. Maintaining the correct aspect ratio prevents images and videos from appearing stretched or squashed.
What aspect ratio is 1920×1080?
1920×1080 pixels is a 16:9 aspect ratio, also known as Full HD or 1080p. It is the most common display resolution for TVs, monitors, laptops, and online video platforms including YouTube and Vimeo.
How do I resize an image while keeping the aspect ratio?
To resize an image proportionally, divide the new width by the original width to get the scale factor, then multiply the original height by the same factor. For example, if your image is 1200×800 and you want a width of 600, the scale factor is 0.5, so the new height is 800 × 0.5 = 400.
What are common aspect ratios for social media?
Common social media aspect ratios include: 1:1 (square, used by Instagram posts), 4:5 (portrait, Instagram), 9:16 (Stories and Reels, TikTok), 16:9 (landscape video, YouTube, Twitter), and 1.91:1 (Open Graph/link previews). Each platform may have specific pixel dimension requirements within these ratios.