You can resize one video for every social media platform by exporting a single master clip into each platform's aspect ratio and length in your browser, without uploading anything. Alvseike Social does the whole job on your device: cut the master, reframe it to 9:16, 1:1 and 16:9, burn in subtitles, and export a correctly sized file for each app. The sections below walk through the full workflow in order, from raw recording to published post.
What each platform actually wants
Most wasted effort comes from exporting one file and hoping it fits everywhere. It does not. Reels, TikTok and Shorts crop a 16:9 clip to a thin strip in the middle, YouTube shows a 9:16 clip with black bars on both sides, and feed posts get cropped differently again depending on where the viewer taps.
| Platform | Placement | Aspect ratio | Practical length |
|---|---|---|---|
| TikTok | Feed video | 9:16 | 15-60 seconds |
| Instagram Reels | Reels tab | 9:16 | 15-90 seconds |
| YouTube Shorts | Shorts shelf | 9:16 | under 60 seconds |
| Instagram feed | In-feed video | 4:5 or 1:1 | up to 60 seconds |
| YouTube | Standard video | 16:9 | any |
| X / Twitter | In-timeline | 16:9 or 1:1 | up to 2:20 |
| Feed video | 1:1 or 16:9 | up to 10 minutes |
Write this table down once and you stop guessing. Every export after that is mechanical.
Step 1: Start from one clean master
Edit your video once, at the highest resolution you have, and keep the audio and captions final at this stage. Do not add platform-specific text overlays yet, because a caption sized for a 16:9 frame will sit half off-screen once the clip is reframed to 9:16.
If your master is a screen recording or a phone clip with the subject off-centre, note where the subject sits in the frame. That tells you how much you can crop before a reframe cuts a head or a hand out of shot.
Step 2: Reframe the master for vertical platforms
Open Aspect Resizer and load the master. Choose 9:16 and position the crop so the subject stays inside the safe area — roughly the middle 80 percent of the frame, since TikTok and Reels overlay buttons and captions on the top and bottom edges. Export this as your vertical master.
This one export covers TikTok, Instagram Reels and YouTube Shorts. If you need a square or landscape version as well, run the same file through again at 1:1 and 16:9 rather than re-editing from scratch.
Step 3: Burn in subtitles before you resize further
Most feed video is watched with sound off. Subtitles are not optional, and adding them after you have already exported three aspect ratios means doing the timing work three times.
Run the vertical master through Auto Subtitles. It transcribes the audio and burns the captions into the video, so the text is part of the file and cannot be switched off or lost when a platform re-encodes your upload. Check the line breaks: a two-line caption centred on the frame reads fine, a four-line block covers the subject.
Do this step before any further resizing, so every later export inherits the captions already in place.
Step 4: Export every platform's size at once
This is where the workflow stops being tedious. Open Social Pack Exporter, load your captioned master, and select the platform sizes you need. It produces the full set — vertical, square and landscape — in a single pass instead of one export per app.
A run is one export, however many files that export contains, so a pack of six sizes counts as one run. Free use without an account allows 5 runs per day and up to 3 files per batch; a free account raises that to 15 runs a day and 5 files per batch. If you publish daily across several accounts, the pricing page explains the Pro plan, which removes the daily metering and the batch cap.
Step 5: Make the still images for the same post
The video is only half the post. You usually need a cover frame, a carousel slide or a story graphic that matches. Social Graphics Maker handles a post, story or header at the correct dimensions, so the still and the video look like they came from the same account rather than two different ones.
Keep one template — same font, same corner placement, same colour — and reuse it across every platform. Consistency is what makes a feed look deliberate.
Step 6: Write the caption and split the thread
If the post is text-first, write the full version once and then cut it down. Long captions that exceed a platform's limit get silently truncated, which is how a call to action disappears.
For X or Threads, paste the full text into Thread Splitter. It breaks a long piece into posts that fit the character limit and numbers them, so you are not manually counting characters or guessing where a sentence should break. Keep the first post strong enough to stand alone, since most people never expand the thread.
Step 7: Read your own account data before you plan next week
Numbers beat instinct. Instagram Unfollowers reads your own account export and shows who does not follow you back, which is useful for deciding where to spend effort and which accounts to stop chasing.
Pair that with the platform's own insights: which format got saves rather than likes, which length held attention, which cover frame got tapped. Then adjust the next batch of exports accordingly — for example, if 9:16 clips consistently outperform 1:1, stop producing the square version.
Why doing this in the browser beats upload-based sites
The obvious difference is privacy. Every tool in Alvseike Social runs locally in your browser, so your footage, your captions and your account data never leave your device. Upload-based editors send your unreleased video to a server you do not control, which is a real problem for client work, pre-launch campaigns and anything under an NDA.
The second difference is friction. There is no upload wait, no queue, no re-download of a file you already have, and no file-size caps — a long screen recording processes as fast as your own machine allows. There are also no watermarks stamped on the output, so you are not paying a subscription purely to remove a logo from your own video.
Common mistakes and pro tips
- Cropping after adding text. Text placed for a 16:9 frame gets clipped in 9:16. Reframe first, then add overlays.
- Exporting the vertical master last. Do 9:16 first, because it is the tightest crop and the one most likely to force a reposition.
- Ignoring the safe area. Keep key text and faces out of the top and bottom 10 percent of a vertical frame.
- One caption for every platform. A TikTok caption and a LinkedIn caption should not be identical; the audience and the tone differ.
- Re-encoding repeatedly. Export each aspect ratio once from the highest-quality master rather than resizing an already-compressed file.
- Forgetting the cover frame. On Reels and Shorts the cover is what gets tapped in the grid. Export a deliberate one instead of letting the app pick a random frame.
- Treating the batch as free. Free plans process up to 3 files per batch without an account or 5 with one; plan your export set so you are not re-running the same pack twice.
A realistic weekly routine
Record or edit once. Reframe to 9:16. Burn in subtitles. Export the full size pack in one run. Build one still graphic from the template. Split the text version for the thread platforms. Publish across the week. At the end of the week, check your account data and drop whichever format underperformed.
That loop takes an afternoon the first time and about twenty minutes once the template and the export presets are set. Everything runs on your device, which means the only thing leaving your machine is the finished post you chose to publish.