Your brand
Previews are approximate. Each network changes its layout by device and over time.
Runs in your browser. Your text stays on this device until you click Schedule this.
Use this tool from code
The same tool is a free API call, no account needed. It also works with our 9 SDKs and the MCP server.
curl -X POST https://postboost.co/app/api/tools/social-media-post-preview -H 'Content-Type: application/json' -d '{"text":"New feature: schedule a month of posts in one sitting."}'
Last verified:
Sources:
- X: counting characters
- LinkedIn (Microsoft Learn): UGC Post API, maximum length of post text
- Sprout Social, social media image sizes guide (updated 2026-05-11)
- LinkedIn Help: image specifications for single-image posts
- Social Media Today (2021): standard-ratio single images on X (then Twitter) show uncropped, very tall or wide ones are centre-cropped
- Hootsuite caption preview: Instagram shows about the first 125 characters (LinkedIn about 140 on desktop, Facebook about 280)
- AuthoredUp: LinkedIn shows about 210 characters on desktop and 140 on mobile before see more
- LetterCounter: Facebook posts truncate after about 477 characters on desktop, 150 to 200 on mobile
Why preview a post before you schedule it
Most people read a post in the feed, not on its own page. What they see there is a cut version: the first lines of the caption, a cropped image and a more link. A post that reads well in a text editor can lose its point at the fold or its headline at the crop. Seeing the feed card first lets you fix that before the post goes out.
What each card shows
Each card counts the caption against that network's limit, with the same counting rules as the character counter, and turns red when the text is too long. It cuts the text where the feed usually folds and keeps your line breaks. Instagram crops the image to the ratio you choose. X, LinkedIn and Facebook show it at its own shape within a range and crop only very tall or very wide images, from the centre.
The networks do not publish their fold positions. The folds here are approximations from published measurements, which differ by device and layout, so leave some room around them.
Write for the fold
Put the hook in the first line, before the fold, and keep the first lines short. Hashtags and links belong after it. On Instagram the name comes first in the caption line, so the first words of the caption have even less room.
Mockups for approval
Download PNG saves a card as an image you can send to a client or teammate for approval. To publish the post to every network at once, schedule it with PostBoost.
How to use
- Type or paste your caption. Line breaks are kept.
- Optionally set the display name and pick an image from your device.
- Choose the Instagram ratio: square, portrait or landscape.
- Check each card: the fold, the crop and the count against the limit.
- Click more to read the full text, or Download PNG to save a mockup.
FAQ
Are these previews exact?
No. Previews are approximate. Each network changes its layout by device and over time, so use the fold and the crop as a guide, not a pixel-perfect copy.
Where does Instagram cut a caption?
The feed shows about the first 125 characters or 2 lines of a caption, then more. The rest is one tap away, so put the hook first.
Where do LinkedIn and Facebook show see more?
LinkedIn folds after about 3 lines or 210 characters. Facebook shows about 480 characters before See more. Folds are approximate: published figures range from about 140 to 210 characters on LinkedIn and from about 150 to 480 on Facebook, depending on device and layout.
Why is my X card red?
The caption is over X's 280-character limit, counted the way X does: links count as 23 characters and emoji and CJK characters as 2. X Premium accounts can post longer texts.
How is my image cropped?
Instagram crops the image from the centre to the ratio you choose: 1:1, 4:5 or 1.91:1. Facebook and LinkedIn show it whole from 4:5 (portrait) to 1.91:1 (landscape) and crop taller or wider images from the centre to the nearest end of that range. X does not publish its cutoff; we use 4:5 to 2:1, the range most guides give. Keep important parts away from the edges.
Is my caption or image uploaded?
Your image never is. The preview runs in your browser: the image is read on your device and the PNG export is drawn there too. Your caption is sent to PostBoost only when you click Schedule this, which opens it as a draft in your account.
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