What this tool does
Aspect Ratio Calculator converts between width, height, and ratio while preserving proportions.
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▭ Aspect Ratio Calculator
Calculate simplified ratios, missing dimensions, orientation, and copyable JSON summaries without sending dimensions anywhere.
Aspect ratio checks
Validates positive dimensions, reduces the ratio with a greatest-common-divisor pass, and reports rounding choices so resized pixel values are reproducible.
Why it is useful
It helps resize videos, images, thumbnails, embeds, slides, and responsive layouts without stretching content.
How it works
The browser reduces the source dimensions to a simplified ratio, then applies that ratio to any target width or height you provide.
Best input
Enter two known dimensions and one target dimension when you need an exact resized result.
Design tip
Round final pixel values carefully when exporting assets for exact platforms.
Privacy note
Aspect-ratio math runs locally in your browser.
Important limitation
Rounding can produce one-pixel differences, and some platforms crop or pad assets even when the ratio is correct.
Quick answers
What ratio is widescreen?
16:9 is the common widescreen video ratio.
Will this crop my image?
No. It calculates dimensions; cropping depends on your editor or platform.
Common Use Cases
Resize images without distortion
Calculate the matching height when changing a thumbnail, product image, or blog hero width.
Prepare social/video assets
Check common 16:9, 1:1, 4:5, and Open Graph dimensions before exporting.
Document layout specs for agents
Copy a deterministic report or JSON summary into an issue, script, or design handoff.