How to Post AI Videos to X (Twitter) Automatically, Within the 280 Limit

To post AI videos to X (Twitter) automatically, connect your X account to ReelMint once, open any video in your Library, press Share, tick X, and publish now or set a time. Each X post costs 2 credits, the caption is measured the way X measures it (a weighted 280), and the video must be 140 seconds or shorter and under 512 MB.

We build ReelMint, an AI video studio that also publishes to TikTok, YouTube, Instagram, Facebook and X. X is the one platform with a price on each post and the strictest caption rule, so this guide spends most of its time on those two.

Step 1: connect your X account

1. Open Channels, then Connections.
2. Press Connect on X. You sign in on X's own page and approve the posting permission.
3. You return to ReelMint with the account listed. A filled dot in the Channels menu means the connection is live.

ReelMint never sees your X password; it keeps an encrypted token. X access tokens last about two hours and X replaces the refresh token every time it is used, so ReelMint renews the connection in the background and stores each new token before the old one stops working. Connecting needs no subscription. More than one X account is fine. The connect-your-channels guide covers every platform.

Step 2: write the X post

Open the video, press Share and tick the X account. The X tab has its own caption box, separate from the TikTok, Instagram, Facebook and YouTube tabs, because an X post and an Instagram caption are different pieces of writing. The AI caption button (1 credit) writes it from the video: one sharp line of at most about 240 characters including the hashtags, a hook rather than a summary, with 1 to 3 hashtags and your own tags first.

Why 280 is not 280 characters

X does not count characters. It counts weight:

• Latin letters, digits and common punctuation count 1.
• Every emoji counts 2, and so do Chinese, Japanese, Korean and most other scripts.
• Any link counts 23, however long or short it is, because X wraps it.

The limit is 280 of those units. A caption with a dozen emojis and a link can pass a plain character count and still be far over. When that happens X does not say "too long"; it answers with a generic "You are not permitted to perform this action", because posts over 280 are a paid X feature. ReelMint avoids that in two places. The counter on the X tab shows the weighted count, not the character count. And at publish time the caption is measured the same way X measures it and trimmed on a word boundary if needed, dropping hashtags before it cuts words and never cutting a link in half.

Step 3: check the video fits X

• Length: 140 seconds at most. Longer videos are refused by X.
• Size: under 512 MB.
• Shape: 16:9, 1:1 or 9:16.

Short AI clips, 30-second cuts and bot reels are well inside this. If you made a longer film, cut an X version in the video editor first. Oversized renders such as an 8K upscale are swapped for a 1080p H.264 copy for publishing, so the upload does not fail on the file itself.

Step 4: publish or schedule

Publish sends it now. A date and time on the X tab schedules it. Each destination has its own time, the scheduler checks every minute, and scheduled posts appear on the dashboard where you can open the post to change or cancel it before it goes out. The scheduling guide has the full flow.

What an X post costs

Publishing to TikTok, YouTube, Instagram and Facebook costs no credits. An X post is the exception: 2 credits per post, which is $0.008 at one credit = $0.004. The Share screen shows "2 per post" next to every X destination so it is never a surprise. The 2 credits apply on every path that posts to X: a manual Share, a scheduled post, a Bot Studio bot, or an AI client over MCP.

How the charge works:

• The 2 credits are reserved just before the post is sent.
• If X accepts it, the reservation is settled.
• If the post fails, the credits are returned. A failed post costs nothing.
• If your balance cannot cover 2 credits, the post fails with "not enough credits: posting to X costs 2 credits" rather than going out unpaid.

Generating the video is what spends most credits, and its price is on the Generate button before you click. Plans start at Lite, $9.99 a month for 800 credits, and every plan runs every AI model.

Posting to X every day without touching it

Bot Studio is a standing recipe: what to make, how long, when, and where. Every firing generates a new video, writes a separate X post alongside the TikTok, Instagram, Facebook and YouTube copy, and publishes. The bot's quote adds a "Post to X" line for each X destination, so the monthly figure you see before saving already includes it. See the autopilot page or the bot guide.

What happens when a post fails

A failed attempt is retried quietly up to three times (after 30 seconds, then 2 minutes). After the third failure you get a notification and an email with X's reason. A rate limit (HTTP 429) is never retried; the destination is paused for six hours so re-posting does not prolong the block, and the pause shows on the dashboard and lifts on its own.

Does posting to X cost credits on ReelMint?

Yes, 2 credits per post, reserved before the post and returned if it fails. Every other platform posts at no credit cost.

Why did X refuse a caption that looked short enough?

Emojis, CJK text and links weigh more than one each in X's count, so the caption was over 280 weighted units. The X tab's counter shows the weighted number, and ReelMint trims to it at publish.

How long can a video on X be?

140 seconds and under 512 MB, in 16:9, 1:1 or 9:16. Longer videos are refused by X.

Can I schedule X posts?

Yes, to the minute, per destination, with its own caption. Scheduled posts are listed on the dashboard and can be cancelled before they go out.