The short version
Fit the complete source inside the new frame and fill the unused area with a color, blur, pattern or extended background. This preserves every source pixel and avoids stretching.
What matters most
- Unmatched ratios always leave unused space when nothing is cropped.
- Bars are a geometry result, not an export error.
- A purpose-designed background usually looks better than automatic blur behind text-heavy content.
How to apply it
- Create a canvas at the target ratio and resolution.
- Scale the source proportionally until it fits entirely inside.
- Center or deliberately align the source.
- Fill remaining space and verify text contrast and safe areas.
Reference table
| Fill choice | Advantage | Watch for |
|---|---|---|
| Solid color | Small and predictable | May look visually detached |
| Blurred duplicate | Uses source colors | Can distract behind text |
| Extended design | Most intentional | Requires manual work |
| Transparent canvas | Flexible downstream | Not supported by every video format |
Use exact dimensions and units in production notes; familiar labels can describe more than one standard.
Common mistakes to avoid
- Zooming until the bars disappear, which silently crops the source.
- Stretching to fill the frame.
- Using black bars when the publishing platform will add a different background.
Continue with the right tool
Use a calculator to check the numbers against your own source and destination instead of relying on a generic preset.
Related guides
What Is Aspect Ratio? A Practical Guide to Image and Video Shape
Understand aspect ratio, how width and height form a ratio, why it differs from resolution, and how to choose the right shape for images and video.
Aspect ratio basicsHow to Find an Aspect Ratio from Width and Height
Find and simplify any aspect ratio from pixel dimensions, with worked examples, decimal ratios and guidance for non-standard sizes.
Aspect ratio basicsHow to Change Aspect Ratio Without Ruining the Composition
Choose between crop, padding and reframing when changing an image or video aspect ratio, with a practical decision process.
Frequently asked questions
Why do black bars appear?
The source and destination shapes differ, so fitting the whole source leaves unused space on two sides.
Are bars always black?
No. You can use any suitable background, although some players add their own neutral bars.
Can AI expansion avoid bars?
It can generate new edge content, but the generated area should be reviewed for artifacts and factual changes.