Find aspect ratio from width and height
Calculate missing width or height
Enter either width or height (not both), then calculate the missing dimension.
Why a video ratio calculator matters
A video ratio calculator helps you size your content correctly for any screen, platform, or player. If your dimensions are wrong, your video may appear stretched, squashed, cropped, or letterboxed. This tool solves that by quickly finding the correct aspect ratio and the exact missing width or height.
Whether you create YouTube tutorials, social media shorts, online courses, or ad creatives, getting aspect ratio right is one of the easiest ways to look more professional.
What is aspect ratio in video?
Aspect ratio is the relationship between a video’s width and height, written as W:H. For example, 1920×1080 simplifies to 16:9. This does not describe quality by itself; it describes shape.
- 16:9 = standard widescreen (most modern video)
- 9:16 = vertical full-screen phone format
- 1:1 = square format
- 4:3 = older TV and presentation format
- 21:9 = cinematic ultrawide
How to use this video ratio calculator
1) Find ratio from dimensions
Enter your width and height in pixels, then click Calculate ratio. The calculator returns:
- Simplified ratio (like 16:9)
- Decimal ratio (like 1.7778:1)
- Closest common format name
2) Calculate missing width or height
Select a preset or enter a custom ratio. Then provide either width or height. Click Calculate dimension and the tool gives you the missing value plus practical rounded suggestions.
Resolution vs aspect ratio (quick clarification)
Resolution is the actual pixel count (for example, 1280×720). Aspect ratio is the shape of that resolution (16:9). Two videos can share the same ratio while having very different resolutions and quality levels.
- 640×360 and 1920×1080 are both 16:9
- Both are the same shape, but one has many more pixels
Common platform targets
YouTube (standard videos)
Use 16:9. Typical sizes: 1920×1080, 1280×720.
Short-form vertical video
Use 9:16. Typical size: 1080×1920.
Instagram feed square posts
Use 1:1. Typical size: 1080×1080.
Cinematic trailers
Use 21:9 when your workflow and delivery platform support ultrawide output.
Practical tips for clean exports
- Match timeline ratio to delivery ratio before editing.
- Prefer even-number dimensions for cleaner encoding compatibility.
- Upscaling changes size, not original detail quality.
- Use safe zones for text, especially on vertical formats.
- When repurposing content, create separate compositions for each ratio.
FAQ
Can I convert 16:9 to 9:16 automatically?
You can resize, but you usually need to reframe to keep subjects centered. A direct convert often crops important parts.
Why does my video have black bars?
Black bars appear when player ratio and video ratio do not match. To avoid this, export in the target platform ratio.
Is 1920×1080 always better than 1280×720?
It has more pixels, but “better” depends on source quality, bitrate, and device. Ratio and resolution should both fit your use case.
What ratio should I use for most projects?
If you only publish one version, 16:9 remains the most universally compatible. For mobile-first social channels, 9:16 is often better.