One shape, many resolutions
An aspect ratio is width compared with height. It has no unit and says nothing about sharpness: 1280×720, 1920×1080 and 3840×2160 are all 16:9. They fit the same frame without cropping, even though their pixel counts differ by a factor of nine from the smallest to the largest.
The calculator reports two answers when they differ. The common ratio is the name people use for a format family, such as 21:9 ultrawide. The exact ratio is the dimensions reduced by their greatest common divisor. That is why 3440×1440 appears as 21:9 and 43:18 at the same time: one is the useful label, the other is the exact arithmetic.
Common aspect ratios
| Ratio | Typical size | Where it is used |
|---|---|---|
| 1:1 | 1080×1080 | Square images and social posts |
| 4:3 | 1600×1200 | Older monitors, tablets and classic video |
| 3:2 | 1500×1000 | Cameras, laptops and photo prints |
| 16:10 | 1920×1200 | Productivity monitors and laptops |
| 16:9 | 1920×1080 | TV, video, gaming and most monitors |
| 21:9 | 3440×1440 | Ultrawide monitors and cinematic frames |
| 32:9 | 5120×1440 | Super-ultrawide monitors |
Scale without stretching
To preserve shape, multiply both dimensions by the same factor. The scale fields above lock the current ratio: change the new width and the height follows, or change the height and the width follows. Rounding to the nearest whole pixel is correct for ordinary images and video.
If your target frame has a different ratio, only three honest choices exist: crop the edges, add empty bars, or distort the image. Stretching may fill the frame, but circles become ovals and people become wider or thinner. For screen-specific measurements, open the screen resolution checker; for the full panel workflow, use the monitor test index.