Aspect Ratio Calculator
Calculate exact image dimensions, find aspect ratios from existing images, and use common presets for social media.
*Enter one value, the other is calculated automatically.
Ready to Calculate
Enter a Width OR Height, the other will be calculated automatically based on the ratio.
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Free Aspect Ratio Calculator: Resize & Scale
Whether you are a web designer creating responsive layouts, a videographer editing footage, or a social media manager resizing posts, maintaining the correct Aspect Ratio is critical. A distorted or cropped image can ruin a professional presentation. Our Advanced Aspect Ratio Calculator helps you resize content perfectly and discover the hidden ratios of your existing files.
Key Features
Smart Resizing
Enter one dimension (Width or Height), and we automatically calculate the other to match your ratio.
Social Presets
One-click presets for Instagram Stories (9:16), Posts (4:5), YouTube (16:9), and more.
Image Detection
Drag & drop any image file to instantly detect its true resolution and calculated aspect ratio.
Cinema & HD
Support for standard HD (16:9), SD (4:3), and cinematic UltraWide (21:9) formats.
Visual Preview
See a live visual representation of your selected ratio to understand the shape before you crop.
Find Ratio
Convert any resolution (e.g., 1920x1200) into its simplest form (e.g., 16:10) using GCD logic.
Why Ratios Matter
Social Media Optimization
Platforms like Instagram and TikTok prioritize specific ratios. Posting a 16:9 landscape video to a vertically scrolling Reel results in a tiny, unengaging video.
Standard Sizes:
- Instagram Story: 1080 x 1920 (9:16)
- Instagram Post: 1080 x 1080 (1:1)
- YouTube Video: 1920 x 1080 (16:9)
Responsive Web Design
Designers use aspect ratios to ensure images scale predictably across devices. Maintaining a consistent ratio prevents "Cumulative Layout Shift" (CLS), which is bad for SEO.
Common CSS Ratios:
aspect-ratio: 16 / 9;object-fit: cover;Frequently Asked Questions
What is an Aspect Ratio?
An aspect ratio is the proportional relationship between the width and height of an image or screen. It is usually expressed as two numbers separated by a colon, like 16:9 or 4:3. It doesn't tell you the exact size (inches or pixels), but rather the shape of the image.
How do I calculate the new height for a specific width?
Use our 'Resize Dimensions' mode. Enter your desired Aspect Ratio (e.g., 16:9) and then type your target Width (e.g., 1920). The calculator will automatically determine the matching Height (1080) to maintain that ratio without distortion.
What is the standard aspect ratio for YouTube?
The standard aspect ratio for YouTube videos on desktop is 16:9. If you upload a video with a different ratio (like 4:3 or 1:1), YouTube will add black bars (pillarboxing) to the sides to fill the player. Our tool has a specific 'YouTube' preset to help you check these dimensions.
What are the best aspect ratios for Instagram?
Instagram supports three main ratios: 1:1 (Square) for standard posts, 4:5 (Portrait) for taller posts that take up more screen space, and 9:16 (Story/Reels) for full-screen vertical content. Using the correct ratio prevents your images from being awkwardly cropped.
How does the 'Find Ratio' feature work?
The 'Find Ratio' tool uses a mathematical algorithm called the Greatest Common Divisor (GCD). If you enter a resolution like 1920x1080, it divides both numbers by their largest common divisor (120) to simplify the numbers down to their smallest whole integer relationship (16:9).
Can I upload an image to find its aspect ratio?
Yes! In 'Find Ratio' mode, you can drag and drop an image file directly onto the tool. We will instantly read the pixel dimensions of the file and calculate its exact aspect ratio for you, so you don't have to check the file properties manually.
What is the 21:9 aspect ratio used for?
The 21:9 aspect ratio (often marketed as UltraWide) is used for cinematic films and ultrawide gaming monitors. It offers a wider field of view than standard 16:9 screens, providing a more immersive experience closer to what you see in movie theaters.
Why do my resized images look stretched?
Images look stretched when you change the width and height independently without respecting the original aspect ratio. Always use a calculator like this one to find the correct matching dimension. For example, if you double the width, you must also double the height.
Is this tool free?
Yes, the Aspect Ratio Calculator is 100% free to use for unlimited calculations. It runs entirely in your browser, so your images are processed locally and never uploaded to our servers, ensuring your privacy.
Does this work for video resolutions?
Absolutely. Aspect ratios apply to video just as they do to images. Use this tool to calculate bitrates, cropping dimensions, or scale factors for video editing software like Premiere Pro, Final Cut, or DaVinci Resolve.