Cross-Posting TikTok and Instagram Reels with Publlish
Learn how to repurpose short-form video content across TikTok and Instagram Reels using Publlish. Schedule the same video to both platforms at once, customise captions per platform, and maximise reach without doubling your workload.
If you're producing short-form vertical video for one platform, you're leaving reach on the table by not publishing it to the other. TikTok and Instagram Reels use the same format — 9:16 vertical video — and Publlish lets you schedule a single video to both platforms simultaneously, with separate captions optimised for each.
This is one of the highest-leverage workflows for any marketing team or agency managing short-form video content.
Why Cross-Post TikTok and Instagram Reels?
The same video can reach two completely different audiences:
- TikTok has a discovery-first algorithm — even accounts with zero followers can go viral. It's the best platform for reaching new audiences who've never heard of your brand.
- Instagram Reels reaches your existing Instagram followers first, then extends to new audiences through the Explore and Reels tabs. It reinforces your brand with people already in your ecosystem.
The content format is identical — both platforms prefer 9:16 vertical video, under 60–90 seconds. The only thing that needs to change is the caption strategy and hashtags.
What Publlish Handles vs. What You Need to Prepare
Publlish handles:
- Publishing the video to both TikTok and Instagram at your scheduled time
- Letting you write separate captions for each platform in one composer window
- Scheduling both in a single action — no need to post separately
You need to handle:
- Producing the video in 9:16 format (1080 x 1920px recommended)
- Removing TikTok watermarks before posting to Instagram (Instagram's algorithm deprioritises videos with visible TikTok logos — export the original file, not the TikTok-downloaded version)
- Writing platform-appropriate captions for each
How to Cross-Post a Video to TikTok and Instagram Reels in Publlish
- In your Publlish dashboard, click New Post
- In the channel selector, select both your TikTok account and your Instagram account
- Upload your video file (MP4, 9:16, 1080 x 1920px recommended)
- Write your caption — Publlish will show a tab for each platform so you can customise per channel
- Add TikTok-specific elements: trending sounds (from Commercial Music Library for Business accounts), hashtags, and a hook-first caption
- Switch to the Instagram tab: write a slightly more polished caption, add your hashtags (3–10 relevant ones), and add a location tag if relevant
- Set your publishing time
- Click Schedule
Both posts will go live simultaneously at your chosen time.
Writing Captions for Each Platform
The same video, two different caption styles:
TikTok caption formula:
- Open with a hook in the first line — make it a question, a bold claim, or a pattern interrupt
- Keep the main body short and conversational
- Add 3–6 trending + niche hashtags
- End with a CTA or open question to drive comments
Example: "Nobody talks about this LinkedIn hack 👀 Here's how we got 3x reach with one simple change. Save this for later. #linkedintips #socialmediatips #marketingtips"
Instagram Reels caption formula:
- First 125 characters are what show before "more" — make them count
- Slightly more polished tone than TikTok
- Add relevant hashtags (can go at the end or in a comment)
- CTA that fits Instagram culture (save, share, follow)
Example: "The LinkedIn reach hack your competitors don't know about. Swipe to see the before & after results. Drop a comment if you want the full breakdown 👇 #LinkedInMarketing #SocialMediaStrategy #ContentMarketing"
Video Spec Comparison: TikTok vs. Instagram Reels
| Spec | TikTok | Instagram Reels |
|---|---|---|
| Aspect ratio | 9:16 (preferred) | 9:16 (required for Reels) |
| Resolution | 1080 x 1920px recommended | 1080 x 1920px recommended |
| Duration | 3 sec – 10 min | 3 sec – 90 sec |
| Format | MP4 (H.264) | MP4 (H.264) |
| File size | Up to 1GB | Up to 1GB |
| Music | Commercial Music Library (Business) | Instagram audio library |
| Watermarks | Remove TikTok watermarks before posting to Instagram |
The TikTok Watermark Problem
If you download a video from TikTok and upload it directly to Instagram, it will have the TikTok logo watermarked on it. Instagram's algorithm deliberately deprioritises videos with TikTok watermarks in the Reels feed.
How to avoid this:
- Always save the original video file from your phone's camera roll or editing software — before uploading to TikTok
- Upload that original file to both TikTok and Instagram through Publlish
- Never download from TikTok and re-upload to Instagram
This is why cross-posting through Publlish from the original file is the right workflow — you post the clean version to both platforms simultaneously.
Adding YouTube Shorts to the Mix
If you're already cross-posting to TikTok and Instagram, adding YouTube Shorts takes less than a minute and gives you a third platform for the same video.
In the Publlish composer, simply select TikTok, Instagram, and YouTube at the same time. YouTube Shorts uses the same 9:16 format and will auto-classify as a Short if the video is under 60 seconds.
YouTube Shorts benefits from keyword-rich titles for search discoverability — add a clear, specific title in the YouTube tab of the composer.
Cross-Posting Checklist
Before scheduling a cross-post to TikTok and Instagram Reels:
- [ ] Video is in 9:16 format (1080 x 1920px)
- [ ] Video is under 90 seconds (Instagram Reels limit)
- [ ] Using original file — no TikTok watermark
- [ ] TikTok caption has hook, hashtags, and CTA
- [ ] Instagram caption has polished hook, hashtags, and CTA
- [ ] Music selected from Commercial Music Library (for Business TikTok accounts)
- [ ] Location tag added to Instagram post if relevant
- [ ] Both channels selected in Publlish composer
Frequently Asked Questions
Can I post the same video to TikTok and Instagram at the same time using Publlish? Yes. Select both channels in the Publlish composer, upload your video, write separate captions for each, and schedule once. Publlish will publish to both simultaneously.
Does the same video work on both TikTok and Instagram Reels? Yes — both platforms use 9:16 vertical video. Videos under 60 seconds work perfectly for both. Videos between 60–90 seconds will work on Instagram Reels but are slightly long for peak TikTok performance.
Will Instagram penalise my Reel for being the same content as my TikTok? Instagram doesn't penalise duplicate video content — but it does deprioritise videos with TikTok watermarks. As long as you're uploading the original file (not downloading from TikTok), you're fine.
Should I post to TikTok and Instagram at exactly the same time? It doesn't need to be simultaneous. Some teams prefer to test on TikTok first, then post to Instagram a day later if the TikTok performs well. Publlish lets you schedule each platform independently if you prefer this approach — just deselect one platform and schedule separately.
Can I add different music to the TikTok and Instagram versions? Yes. Music selection is platform-specific in the Publlish composer. Add a TikTok sound for TikTok and an Instagram audio for the Reel — they're independent.