What does an aspect ratio tell you?
An aspect ratio describes the relationship between an image or video’s width and height. It is written as two numbers separated by a colon, such as 16:9 for widescreen or 9:16 for vertical video. The ratio describes the shape of the frame, not the number of pixels or the quality of the image.
Use this aspect ratio calculator when you know a frame’s pixel dimensions and want to identify its shape, or when you need a new width or height that keeps the same proportions. The calculator runs in your browser and does not need a video upload.
How to calculate an aspect ratio
Divide the width and height by their greatest common divisor to simplify the ratio. For example, 1920 × 1080 pixels simplifies to 16:9 because both numbers can be divided by 120. A 1080 × 1920 frame simplifies to 9:16.
Matching height = new width ÷ (width ÷ height)
If the dimensions do not reduce to small whole numbers, a calculator can still show the ratio as a decimal or help you select a common target ratio. For a worked explanation, read the aspect ratio formula guide.
Common aspect ratios and dimensions
| Aspect ratio | Example dimensions | Common use |
|---|---|---|
| 9:16 | 1080 × 1920 | Vertical short-form video and portrait stories |
| 16:9 | 1920 × 1080 | Widescreen video and standard landscape players |
| 1:1 | 1080 × 1080 | Square images and social posts |
| 4:5 | 1080 × 1350 | Tall portrait feed images |
| 4:3 | 1440 × 1080 | Classic landscape photos and video |
These are common examples, not universal platform requirements. Check the current export guidance for the service you are publishing to, especially when a platform offers different display placements.
Aspect ratio vs. resolution: what is the difference?
Resolution is the actual pixel width and height. Aspect ratio is the relationship between those numbers. For example, 720 × 1280 and 1080 × 1920 both have a 9:16 ratio, even though the second frame has more pixels. A larger resolution does not automatically make footage look better if the source is low quality or heavily compressed.
Resize, crop, or stretch?
- Resize proportionally when you want a smaller or larger version without changing the image shape.
- Crop when the destination needs a different ratio and you can remove parts of the edges.
- Avoid stretching to force one ratio into another; it distorts people and objects.
To inspect a photo’s real dimensions and preview a crop to a standard shape, try the Image Aspect Ratio Checker.
Frequently asked questions
What is the aspect ratio of 1920 × 1080?
It is 16:9. Divide both dimensions by 120: 1920 ÷ 120 = 16 and 1080 ÷ 120 = 9.
What aspect ratio should I use for vertical video?
9:16 is a common full-height vertical format, often produced at 1080 × 1920 pixels. Confirm the platform’s current recommendations and consider where interface controls or captions may cover the frame.
Can two resolutions have the same aspect ratio?
Yes. Any width and height that preserve the same proportion share an aspect ratio. For example, 720 × 1280 and 1080 × 1920 are both 9:16.
Does changing the aspect ratio reduce quality?
Changing only the ratio does not inherently reduce quality, but cropping removes visible content, stretching distorts the image, and resizing may resample pixels. Export settings and source quality also matter.
Need the ratio from a real image?
Check an image