Calculate a matching height from a width, compare landscape and portrait ratios, and distinguish proportional resizing from cropping.
A ratio describes shape, not image detail. Keeping the ratio prevents stretching, but it does not guarantee that a small source image will look sharp when enlarged. Decide whether you need the whole picture or a crop for a different shape.
Worked example: Find the height of a 16:9 image
Input
A width of 1,280 pixels and an aspect ratio of 16:9.
Expected result
A height of 720 pixels. For a portrait 9:16 layout at 720 pixels wide, the height is 1,280 pixels.
For 16:9, multiply the width by 9 and divide by 16. Swapping 16:9 to 9:16 changes the orientation; it does not rotate or crop the source image by itself.
Before you use the result
- Check which field is width and which is height.
- Round to whole pixels only when the export format requires it.
- Use a crop or borders when the destination needs a different shape.
If the result is not what you expected
The dimensions are correct but the picture looks blurry.
The calculation preserves proportions, not missing detail. Use a larger source or export at a smaller size.
Step-by-Step Walkthrough
Enter Dimensions
Type your starting width or height in pixels.
Pick a Ratio
Select a preset like 16:9 for landscape video or 9:16 for mobile reels.
Copy Measurements
Copy the resulting dimensions or the CSS aspect-ratio code snippet.
Key Capabilities & Features
Bi-directional dimension calculation
enter width or height to get matching pixels
One-click aspect ratio locking for 16
9, 9:16, 1:1, 4:3, 21:9, and 3:2
Preloaded resolutions for YouTube, TikTok, Instagram, and widescreen monitors
Visual scaling preview box and instant CSS aspect-ratio code generator
Frequently Asked Questions
Ready to try Aspect Ratio & Screen Dimensions Calculator?
Open Aspect Ratio & Screen Dimensions Calculator and try the example from this guide. Check the tool page for supported formats, limits, and access requirements.