Social media crops
Check whether an image fits a square, vertical, or widescreen crop before you publish it.
Developer Tool
Aspect Ratio Calculator
Upload an image and calculate its aspect ratio instantly in your browser. See the exact width, height, reduced ratio, decimal ratio, and orientation without sending the file to a server.
Input
Upload an image to read its proportions
Choose a local image or drop one into the upload area. The tool reads the image dimensions in your browser and shows the simplest width-to-height ratio.
Drag and drop
Drop an image here
JPG, PNG, WebP, GIF, and most other browser-supported image formats work here. The preview appears as soon as the file is loaded.
Waiting for an image upload.
Original Dimensions
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Reduced Ratio
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Decimal Ratio
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Preview
Image preview and ratio result
Upload an image to see the preview
The preview appears here after the file loads.
Upload an image to calculate its aspect ratio.
Orientation
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Ratio Value
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Quick read
This tool reads the image dimensions in your browser and converts them into a clean ratio, which is useful when you need a fast answer for crops, design handoff, or layout planning.
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TL;DR
What this aspect ratio calculator does
Upload an image, and the tool tells you the exact width, height, reduced ratio, decimal ratio, and orientation. It is fast, private, and fully browser-based.
Summary
Calculate image proportions without leaving the browser
Aspect ratio describes the relationship between width and height. It is one of the quickest ways to understand how an image will crop or fit inside a layout. This calculator reads the image metadata and reduces the dimensions to the simplest possible ratio.
How It Works
How the calculator reads your image
The page loads your file locally, creates an in-browser preview, and reads the image's natural width and height. It then computes the greatest common divisor so the final ratio is shown in its simplest form.
- Upload an image and inspect the original dimensions.
- See the ratio reduced to the smallest whole-number form.
- Check the decimal value for a more precise comparison.
- Keep the workflow fast and private because it runs locally.
How To Use It
How do you use the Aspect Ratio Calculator?
- 1
Choose an image from your device or drop it into the upload area.
- 2
Wait for the tool to read the image dimensions and reduce them to the simplest ratio.
- 3
Review the ratio, decimal value, and orientation to confirm the image proportion.
- 4
Copy the ratio if you need to share it with a designer, editor, or developer.
Use Cases
Where aspect ratio checks are useful
Thumbnail planning
Match preview images to the platform ratio you need for YouTube, app stores, or marketing pages.
Responsive layouts
Keep banners and hero images aligned with a consistent proportion across different screen sizes.
Design handoff
Share exact image proportions with designers and developers so crops and exports stay aligned.
FAQ
Common questions
These answers are written for fast scanning and direct answer extraction, which makes them useful for search snippets and AI answer surfaces.
What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height. It is usually written as two numbers separated by a colon, such as 16:9 or 4:3.
How does this aspect ratio calculator work?
Upload an image and the tool reads its natural width and height in your browser. It then reduces those numbers to the simplest ratio and shows the decimal proportion too.
Does the tool change my image?
No. The image is only read locally so the tool can inspect its dimensions. Nothing is resized or compressed, and the file is not sent to a server by this page.
Can I use it for social media and web design?
Yes. Aspect ratio is useful when you are planning crops for social media, thumbnails, landing pages, banners, and responsive layouts. It helps you keep visual composition consistent.
What are common aspect ratios?
Common ratios include 1:1 for square images, 4:3 for classic photo framing, 16:9 for widescreen layouts, and 9:16 for vertical video and mobile-first content.
Is this calculator browser-only?
Yes. The calculation runs in your browser session, which makes it fast and privacy-friendly for local image checks.
References
Sources behind the tool
- MDN File API : Reference for reading local files in the browser.
- MDN naturalWidth : Browser image metadata used to read the loaded image width.
- MDN naturalHeight : Browser image metadata used to read the loaded image height.
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Last reviewed: May 2026