Resizing an image or video without distorting it means keeping its aspect ratio — the relationship between width and height. This calculator simplifies any pair of dimensions into ratio form, works out the missing side when you know one dimension and the ratio, and lists common presets such as 16:9 for video, 4:3 for older screens, 1:1 for social posts and 9:16 for phone stories. A pixel table shows standard sizes at your ratio.
How Ratios Simplify
A ratio is reduced by dividing both numbers by their greatest common divisor, so 1920 by 1080 becomes 16:9 — the same shape in the smallest whole numbers. When you supply a target width or height instead, the tool scales proportionally and rounds to whole pixels, noting that heavy rounding on tiny images can wobble the ratio slightly. The preset buttons let you compare your media against the shapes platforms expect before you export.
How to Use the Calculator
- Enter the original width and height to see the simplified ratio.
- Or click a preset such as 16:9 or 9:16 to start from a standard shape.
- Enter a new width or a new height — the other dimension is calculated.
- Check the pixel table for ready-made sizes at this ratio.
- Use those dimensions in your editor or export settings.
Where Ratios Matter
Video editors match sequence settings to footage. Designers crop photos for banners and thumbnails without squashing faces. Web developers reserve space for images with CSS aspect-ratio so pages do not jump while loading. Presenters check that slides match the projector. One quick calculation up front prevents the stretched logos and letterboxed embeds that come from guessing.
Frequently Asked Questions
What ratio is a phone screen?
Most modern phones are around 9:19.5 in portrait, but the story and reels format is standardised at 9:16, which is the preset to use for vertical video.
Why is my calculated height a decimal?
Not every width divides neatly. The tool rounds to the nearest whole pixel; a difference of one pixel is invisible at normal sizes.
Is aspect ratio the same as resolution?
No. Resolution is the actual pixel count; the ratio is only the shape. A 16:9 video can be 1280 by 720 or 3840 by 2160.