Aspect Ratio Calculator
Original Size
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Common Ratios
New Size
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Aspect Ratio Calculator — Resize Proportions Instantly
Aspect Ratio Calculator finds the missing width or height while keeping proportions intact. Enter a ratio (like 16:9) and one dimension, and the tool returns the other dimension plus the new size for your resize task.
Features & Usage Tips
Enter a ratio and one dimension to instantly get the matching width or height — perfect for maintaining proportions when resizing.
How Aspect Ratio Works
An aspect ratio describes the proportional relationship between width and height (e.g. 16:9, 4:3, 1:1). Given any ratio and one known dimension, the unknown dimension can be calculated directly while preserving the proportion.
- Ratio Presets: Common ratios (16:9, 4:3, 3:2, 1:1, etc.) are one click away, or type a custom ratio.
- Any Known Dimension: Enter either width or height; the other is computed automatically.
- New Size Output: See the resulting dimensions together, ready to use in your design or code.
Use Cases
🖥️ Video & Thumbnails: Resize thumbnails or video frames to 16:9 without distortion.
📐 Design & Print: Maintain 4:3 or 3:2 ratios for photos, posters, and social media images.
🎨 UI & Icons: Generate consistent icon or image sizes from a single ratio.
📱 Responsive Layouts: Compute proportional dimensions for responsive images across breakpoints.
Privacy & Security
This tool runs entirely in your browser. All ratio calculations are performed locally — your values never leave your device.