TranslateAspect Ratio Calculator
Calculate and convert aspect ratios for videos, images and screen sizes.
Auto-Detect from Image
Drop an image here to detect its ratio instantly
or click to browse - 100% private, nothing is uploaded anywhere
Detect from URL
Enter Dimensions
Visual Preview
1920 × 1080
16:9 · Landscape
Results
Smart Tips
This is the YouTube / HD standard. For thumbnails use 1280 x 720 - same ratio, smaller size.
Modern CSS Generator
Container
.aspect-box {
width: 100%;
aspect-ratio: 16 / 9;
}Image
img {
width: 100%;
aspect-ratio: 16 / 9;
object-fit: cover;
}Video
video {
width: 100%;
aspect-ratio: 16 / 9;
}Resolution Presets
Device Presets
My Custom Presets
Common Ratios
How to Use the Aspect Ratio Calculator
Fastest Workflow
- Drop any image into the Auto-Detect zone - dimensions and ratio fill in instantly.
- Or paste a YouTube / Instagram / TikTok link and hit Detect for that platform's standard size.
- Or type dimensions manually - results update live as you type.
- Export a full report with one click when you need to share the numbers.
Which tab do I need?
- Calculate: See the ratio of any dimensions.
- Find Missing: You know one side and the ratio - get the other side.
- Resize: Shrink or grow while keeping the ratio intact.
- Compare: See which of two sizes has more pixels.
- Screen Size: Turn a TV or monitor diagonal into real pixel dimensions.
About This Tool
The Aspect Ratio Calculator is a free online tool that helps you calculate and convert aspect ratios for images, videos, and screens. Have you ever tried to resize a photo for Instagram or a YouTube thumbnail, only to end up with an image that looks stretched or squished?
This tool fixes that by doing the math for you. It helps you find missing dimensions, resize files without ruining the proportions, and compare different screen sizes. It also comes pre-loaded with presets for popular devices (like iPhones and MacBooks) and social media platforms.
Plus, developers can use the built-in CSS generator to instantly get modern aspect-ratio code. Everything runs locally in your browser.
How to Use
- 1Select the tab you need (Calculate, Find Missing, Resize, Compare, or Screen Size).
- 2Enter your Width and Height into the input boxes.
- 3View the instant results showing your simplified ratio, decimal value, total megapixels, and orientation.
- 4Use the "Quick Ratios" or "Device Presets" buttons to automatically apply standard sizes (like 16:9 or iPhone 15 Pro).
- 5Copy the generated modern CSS code if you are building a website.
Frequently Asked Questions
An aspect ratio is the proportional relationship between the width and height of an image or screen. It is usually written as two numbers separated by a colon (like 16:9 or 1:1). It tells you the shape of the rectangle, but not the actual size.
If you know the width is 1920px and the ratio is 16:9, go to the "Find Missing" tab. Enter 1920 as the width, set the ratio to 16:9, and the tool will instantly calculate that the height must be 1080px.
Yes! When you enter any dimensions in the "Calculate" tab, the tool automatically generates modern CSS code using the aspect-ratio property. You can copy this code to make responsive video containers or image holders that never lose their shape.
16:9 is the standard widescreen ratio used by YouTube, modern TVs, and most computer monitors. 4:3 is the older, squarer shape used by traditional tube TVs and some vintage video formats.
Yes. All calculations happen directly inside your web browser using JavaScript. Your image dimensions and projects are never uploaded to a server or tracked.
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