postfit

Does your post fit? Paste your text and see how it counts on X, Bluesky, Threads, Mastodon, LinkedIn and Instagram. The part that won't fit gets highlighted, and long text can be split into a thread.

Try it → https://idea2tool.github.io/postfit/ · see a demo

中文说明

Why

On X, Chinese, Japanese and Korean characters count as 2, most emoji count as 2, and every link counts as 23 no matter how long it is. If you write in CJK or use a lot of emoji, posts overflow long before you expect. postfit shows you exactly where the limit is.

Features

• Live counts for X, X Premium, Bluesky, Threads, Mastodon, LinkedIn and Instagram
• Highlights the exact part that goes over the limit
• X Premium: shows where the timeline collapses your post behind "Show more" (280)
• Splits long text into a thread, breaking at paragraphs and sentences first, with optional 1/3 numbering
• Stats: characters, CJK characters, words, links, emoji
• English and Chinese UI
• Single page, no dependencies, no tracking

How accurate is it?

Platform	How it counts	Source
X	Exact. Weighted by Unicode range, emoji = 2, links = 23, NFC-normalized	twitter-text config v3
Bluesky	Exact. 300 graphemes	AT Protocol lexicon
Threads, Mastodon, LinkedIn, Instagram	Approximate. Counted by graphemes	No public exact algorithm

A note on emoji: the twitter-text package on npm has an outdated emoji list, so it counts newer emoji such as 🧑‍💻 as 5 and 🫶🏻 as 4. I checked them in the x.com composer, and X itself counts both as 2. postfit follows the website.

Run the tests:

node test/count.test.mjs

Privacy

Everything runs in your browser. Nothing is uploaded. Your draft is saved in localStorage on your device only.

Run locally

The page loads count.js as an ES module, so it needs a local server:

python3 -m http.server 5174

Then open http://127.0.0.1:5174/

Made with AI by @idea2tool. MIT License.

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中文说明

推文字数计算器：把要发的内容粘贴进来，就能看到在 X、Bluesky、Threads、Mastodon、LinkedIn、Instagram 上各算多少字。超出上限的部分会用荧光笔标出来，太长还能一键拆成串推。

在线使用 → https://idea2tool.github.io/postfit/?lang=zh · 看演示

为什么需要它：在 X 上，中日韩文字每个算 2，大部分 emoji 算 2，链接不管多长都算 23。用中文发推，经常写到一半才发现超了。

• 各平台实时计数，超出部分标黄
• X Premium：标出时间线折叠成「显示更多」的位置（280）
• 拆成串推：优先在段落、句子结尾断开，可以加「1/3」编号
• X 和 Bluesky 按官方规则精确计算；其他平台没有公开算法，标「约」
• 全部在浏览器里运行，不上传；草稿只保存在你自己的设备上