Aspect ratio calculator finds the simplified ratio for any width and height — 1920×1080 becomes 16:9, 1280×720 is also 16:9, 1024×768 is 4:3.
About this calculator
Aspect ratio calculator finds the simplified ratio for any width and height — 1920×1080 becomes 16:9, 1280×720 is also 16:9, 1024×768 is 4:3. You can also fix a target ratio and compute the missing dimension when scaling video or thumbnails.
YouTubers export at 16:9 (1920×1080 or 3840×2160). Instagram Reels use 9:16 vertical. Old CRT monitors were 4:3. Wrong aspect ratio causes black bars or stretched images.
For display sharpness check [[ppi]] on your monitor. Photographers resizing prints can pair with [[percentage]] for scale factors. Video editors cross-check frame dimensions against [[average]] bitrate planning tools.
Common uses
- YouTuber confirming export is 16:9 before upload
- Web designer scaling hero image from 1920px width to 16:9 height
- Checking if phone screenshot matches 9:16 Reels format
- Comparing two monitor resolutions for same aspect ratio
- Student learning GCD simplification with pixel dimensions
Frequently asked questions
What aspect ratio is 1920×1080?
16:9. Both 1920/1080 and 1280/720 reduce to the same ratio. Full HD, HD, and 4K UHD (3840×2160) all use 16:9 — the most common video and TV standard today.
How do I convert 4:3 photo to 16:9 without stretching?
Crop or add letterbox bars. Calculate target height as width × 9/16 (or width as height × 16/9). Select
What is the aspect ratio of Instagram Reels?
9:16 vertical — height is 16 units for every 9 units of width. A 1080×1920 export is standard. Enter 1080 and 1920 here to verify.
Why do two different resolutions share the same aspect ratio?
Aspect ratio is the proportional relationship, not absolute pixels. 640×360, 1280×720, and 1920×1080 are all 16:9 — they differ in resolution (sharpness), not shape.