What this tool does
Create social-ready video dimensions without uploading the source to ToolsDiary. Choose a common platform preset or custom width and height, decide whether to fit the whole frame or fill it with a centered crop, preview the target framing, and export a new browser-encoded video.
Social platforms support several aspect ratios and can change their publishing rules over time. The presets here are practical starting sizes, not a guarantee that every placement will display identically. The tool keeps the source video on your device, uses the browser codecs available on your system, and reports the actual output format after encoding.
Useful for
- Turn landscape clips into vertical 9:16 videos for short-form feeds.
- Create 4:5 portrait or 1:1 square versions for social feed posts.
- Resize one source video into several platform-friendly versions without installing a desktop editor.
- Create an exact custom canvas when a publisher, ad platform or CMS requests specific dimensions.
How to use it
- Choose a video and wait for its dimensions and duration to appear.
- Select a social preset or choose Custom and enter the target width and height.
- Choose Fit to keep the complete frame with a background, or Fill / crop to cover the target canvas edge to edge.
- Check the framing preview, select output quality, then start the local resize.
- Preview the generated video and download it if the dimensions and framing look right.
Practical tips
- Use 9:16 for full-screen vertical short-form video, 1:1 for square layouts, and 4:5 when you want a taller feed post without going fully vertical.
- Fit never cuts off the source frame, but it can add bars around the video. Pick a background color that suits the content.
- Fill / crop removes empty bars by cropping the left and right or top and bottom edges. Keep important text and faces away from the extreme edges.
- Browser encoding runs in real time and can be demanding on long or high-resolution files. Keep the tab open until export finishes.
- Always keep the original video. Re-encoding can reduce quality and may remove source metadata.
Frequently asked questions
Are videos uploaded to ToolsDiary?
No. Supported source videos are decoded, resized and re-encoded locally in your browser. ToolsDiary does not receive the source or generated video.
What is the difference between Fit and Fill / crop?
Fit keeps the complete source visible and adds background space when the aspect ratios differ. Fill / crop enlarges the source until the target canvas is covered, so some edges can be cropped.
Why is the output sometimes WebM instead of MP4?
Browser encoding support differs. The tool detects formats the current browser can create and uses a compatible option, then labels the actual result.
Do these presets guarantee acceptance on every social platform?
No. They are useful publishing presets based on common aspect ratios and dimensions. Platforms can change technical requirements, recompress uploads or crop previews differently, so check the destination platform when a placement has strict rules.
Can I use custom dimensions?
Yes. Choose Custom and enter an even width and height. For browser stability, this version limits custom output to 2160 pixels per side and roughly 4.2 million pixels total.