Every platform has two numbers that matter: the maximum length you are allowed and the much shorter length that actually performs. This guide gives the current character limits and practical sweet spots for Instagram, Facebook, X, LinkedIn, TikTok, YouTube, Pinterest, and Threads — captions, titles, descriptions, and video runtimes — plus the truncation cutoff on each platform (the "see more" line that decides whether anyone reads past your hook), why the limit is a ceiling and not a goal, and the resizing-for-text tax that hits the moment you post one idea to eight feeds at once.
There is no one ideal length for a social media post, and any page that gives you a single number is selling a simplification. What is true is that every platform has two numbers worth knowing: the maximum it will let you post, and the much shorter length that actually performs. The gap between them is large — Instagram allows a 2,200-character caption and rewards one closer to 125, X allows 280 characters (or 25,000 for Premium subscribers) and engagement tends to peak around 70–100 — and the single most useful habit you can build is to treat the limit as a ceiling, never as a target.
This guide gives the current limits and the practical sweet spots for the platforms Kompozy publishes to — Instagram, Facebook, X, LinkedIn, TikTok, YouTube, Pinterest, and Threads — for captions, titles, descriptions, and video runtimes. But the numbers are the easy part. The two things that actually change your results are understanding where each platform truncates your post (the "see more" line that decides whether anyone reads past your first sentence) and matching length to intent rather than to the size of the box. The figures below are drawn from Hootsuite's 2026 length guide, cross-checked against platform specs and other published guidance; where studies disagree on an exact engagement number, this page generalizes rather than pretends to a precision the data does not support. It is the text companion to the social media image sizes guide, which covers the visual dimensions for the same platforms.
Almost every mistake with post length comes from confusing the maximum with the target. The character limit is the point at which the platform stops accepting text; it says nothing about the length that gets read, watched, or acted on. Those are almost always far apart, and they are apart for a reason: feeds are scrolled on phones by people deciding in a fraction of a second whether to stop. A wall of text is a signal to keep scrolling. A tight, single-idea post that makes its point before the reader has to work for it is what earns the stop.
So the working rule is simple. Use the limit only to know what you cannot exceed, and write to the intent instead — shorter for a feed caption whose job is to earn a tap, longer only where the platform actively rewards dwell time and the substance justifies it. The platforms that reward length are the exception (LinkedIn, a YouTube description, a blog-style article), not the rule, and even there the opening still has to do the work of a short post. Length is a lever; it is a weaker one than most people think, and the stronger lever sits inside the first line.
Behind every platform sit two numbers, and the second one gets ignored far too often. The first is the hard character limit. The second — the one that actually shapes how you write — is the truncation cutoff: the number of characters or lines a platform shows before it collapses the rest behind a "see more," "more," or "…" link. On a feed, most people never tap that link. Whatever sits after it is effectively invisible to the majority of your audience, which means the truncation cutoff, not the character limit, is the real constraint on a caption.
This is why front-loading beats everything. The hook, the payoff, the call to action, the reason to care — all of it has to live before the cutoff, because that is the only part guaranteed to be seen. A brilliant final line under a two-line Instagram preview is a brilliant line almost no one reads. Practically, this reframes the whole question of length: you are not writing to a total, you are writing a first sentence strong enough that the length after it becomes optional. The craft of that opening line is a bigger determinant of performance than any character count on this page.
The caption limit is 2,200 characters, but Instagram collapses a caption after roughly 125 characters — about two lines — behind a "more" link. That cutoff is the number that matters. Widely cited guidance puts the best-performing organic caption around 125–150 characters and sponsored captions under 125, so in practice you are writing to the preview line and treating anything longer as a bonus most people will not expand. Keep hashtags to a focused 3–5 rather than a block of thirty; the era of hashtag stuffing is over. Reels and Stories are their own format, covered under video below.
Facebook has the most generous limit on this list — 63,206 characters — and one of the shortest ideal lengths. The commonly cited sweet spot for organic posts is around 40–80 characters, and ad copy tends to perform tightest at roughly 5–19 words. The reason short wins on Facebook is that for link posts the status text matters less than the linked article's own title and preview, so a brief framing line plus a strong link beats a paragraph. When you do post longer, the same truncation logic applies: a "see more" collapses the post after a few lines, so the point goes first.
Standard accounts still get 280 characters; Premium subscribers can post up to 25,000. But the performing length is far below either — commonly cited figures put the engagement sweet spot around 71–100 characters, and even the studies that disagree on the exact peak agree that posts well short of 280 outperform ones that fill the box. Treat the directional takeaway as the reliable one: one tight idea beats a crammed tweet. Attached media, polls, and quote-posts do not count against the character limit, so a short line plus an image is a strong default.
LinkedIn is the clearest case where longer can work — the platform rewards dwell time, so posts in the roughly 1,200–1,600 character range can outperform short ones when the substance holds attention. The post limit is 3,000 characters. But the truncation cutoff is brutal and early: LinkedIn collapses a post after about 140–210 characters (two to three lines) behind a "see more," so even a long post lives or dies on whether the first two lines earn the click to expand. Native articles and newsletters are a different unit entirely, running comfortably to 1,900–2,000 words. Front-load the post; let the depth pay off after the tap.
TikTok raised its caption limit to 2,200 characters, which tempted a lot of creators into writing essays under their videos. Resist it. The caption's job is to support the video and feed TikTok's search — a short, keyword-aware line (commonly cited as strongest around 50–150 characters) does that without burying the video under text. On TikTok the length that matters is the video's, not the caption's: the caption is a supporting label, and the runtime is the content. See the video section below for the runtime sweet spots.
YouTube is a metadata platform as much as a video one, and three lengths matter. Titles perform best around 60–70 characters against a 100-character limit — long enough to be descriptive, short enough not to get truncated in search and suggested feeds. Descriptions run to 5,000 characters, but only the first 100–150 show above the "show more" fold, so the hook, links, and keywords go there. Runtime is covered below. The discipline is the same as everywhere else: write the front of every field as if the back will be hidden, because it usually is.
Pinterest pin descriptions can run to 500 characters, but around 300 is the practical target — enough to describe the pin and carry the keywords Pinterest search runs on, without padding. Pinterest is a search engine wearing a feed, so descriptions lean more useful and keyword-rich than clever. Threads inherits Instagram's brevity: a 500-character limit, but posts under about 200 characters fit the fast, conversational cadence of the feed. On both, the same front-loading rule holds — the opening carries the weight.
For the video-first platforms, runtime is the real "length," and the numbers cluster tighter than caption lengths do. Instagram Reels and Stories perform best in the 15–60 second range (Reels now run up to about 3 minutes, but longer is rarely better). TikTok's organic sweet spot is similar — roughly 15–60 seconds, even though the ceiling is 10 minutes — with ads tightest around 21–34 seconds. YouTube splits in two: Shorts live in the 30–60 second band (up to 3 minutes), while long-form typically performs in the 7–15 minute range depending on the topic. LinkedIn video does best short, around 30–90 seconds. Facebook video sits around 30–60 seconds for feed posts.
The through-line is that short-form is the default frame across almost every platform, and the winning runtimes are far below the maximums the platforms allow — the same ceiling-not-goal rule that governs captions. The strategic version of this, and why vertical short-form became the baseline unit of distribution, is covered in the short-form content strategy guide; the format itself is defined in the short-form video glossary entry.
Knowing the numbers is the easy half — this page just handed you the whole table. The work is that you are almost never posting to one platform. You are taking one idea and sending it to Instagram, Facebook, X, LinkedIn, TikTok, YouTube, Pinterest, and Threads, and each of those wants a different length, a different first line before a different truncation cutoff, and in several cases a different video runtime. A caption that is perfect for Instagram is too long for X, too short to earn LinkedIn's dwell-time payoff, and mis-keyworded for Pinterest search.
The naive fix — write one caption and paste it everywhere — is exactly what the truncation cutoffs punish. A 300-character caption dumped onto X gets hard-truncated at 280 mid-sentence; the same caption on Facebook buries a link that should have led; on LinkedIn it wastes the two lines that decide whether anyone expands it. Doing it right by hand means rewriting the same idea to a different target length and a different opening for each destination, every time you post. That per-platform rewrite is a real, recurring tax, and it is the reason most cross-posting is done badly — the same way the cross-posting guide describes the resizing tax on images.
The social media image sizes guide makes the point that Kompozy generates each visual natively at its destination's dimensions instead of resizing one master afterward. The text side works the same way, and it is the more overlooked half. Kompozy is an AI content generation and publishing engine, and when it fans one idea across platforms it does not write a single caption and truncate it — it generates the copy per destination, so each platform gets a post shaped to its own length and cadence rather than a one-size caption that reads wrong on seven of them.
Two things make that concrete rather than a claim. First, voice: the Persona Brief governs tone, phrasing, and banned words on every generation, so an X post that lands in 90 characters and a LinkedIn post that earns its 1,400 both still sound like you — the length changes, the identity does not. Second, the guardrail: Kompozy carries a per-platform length model into publishing, so text is fitted to each platform's limit before it ships (an X post held under 280, a Threads post under 500) rather than being blindly truncated mid-word at the API. That means the front-loading discipline this whole page is about — hook first, point before the cutoff — is baked into how the copy is generated, not something you re-apply eight times by hand.
From there the same engine produces the matching assets in 18 output formats — a Reel-length Persona Short with captions in the 9:16 frame, a Carousel, Quote Graphics, a Blog Article for the long-form surface, an Email Newsletter — and publishes the whole set across nine social platforms plus blog and email from one queue, on Autopilot behind a per-post review gate, with brand-exact styling handled by HyperFrames. The point of this page is the numbers; the point of an engine is never having to write one idea to nine different lengths by hand again. Get the first line right, keep the important part before the cutoff, treat every limit as a ceiling — and let the per-platform shaping be the machine's job, not yours.
There is no single number — it depends on the platform, and the honest rule is to treat the character limit as a ceiling, not a target. Practical 2026 sweet spots: Instagram captions land best around 125–150 characters, Facebook posts around 40–80, X posts around 71–100 (against a 280-character limit), LinkedIn posts front-loaded before the roughly 140-character "see more" cutoff, TikTok captions short but keyword-rich, and Threads under about 200. In almost every case the performing length is far shorter than the maximum, and getting the first line right matters more than length.
The maximums, which are much larger than the ideal lengths: Instagram captions 2,200 characters, Facebook posts 63,206, X 280 for standard accounts and up to 25,000 for Premium, LinkedIn posts 3,000, TikTok captions 2,200, YouTube titles 100 and descriptions 5,000, Pinterest descriptions 500, and Threads 500. These are the ceilings the platforms enforce, not what you should aim for — most posts perform best at a fraction of them.
Short, with the important part first. The limit is 2,200 characters, but Instagram truncates a caption after roughly the first 125 characters (about two lines) with a "more" link, so the hook, the point, or the call to action has to live before that cutoff. Widely cited guidance puts the strongest-performing caption length around 125–150 characters for organic posts and under 125 for sponsored ones. You can write longer when the story earns it, but front-load it either way.
Well under the limit. Standard accounts get 280 characters (Premium subscribers can post up to 25,000), but posts perform best far shorter — commonly cited figures put the sweet spot around 71–100 characters. The data on exactly where engagement peaks is mixed across studies, so the reliable takeaway is directional: a tight, single-idea post beats one that fills the box. Media, polls, and quote-posts do not count against the character limit.
Length itself is a weaker lever than what you do with the first line. Every text platform truncates a post after a line or two and hides the rest behind a "see more" tap, so the opening — not the total length — decides whether anyone reads on or scrolls past. Matching length to intent helps (shorter for feed captions, longer where the platform rewards dwell time like LinkedIn), but the highest-leverage move is putting the hook and the point before the truncation cutoff, on every platform.
There is no single ideal social media post length — each platform has a maximum you are allowed and a much shorter length that actually performs, so the rule is to treat the limit as a ceiling, not a goal. Practical 2026 sweet spots: Instagram captions around 125–150 characters, Facebook posts 40–80, X posts 71–100 (limit 280, or 25,000 for Premium), LinkedIn posts front-loaded before the ~140-character "see more" cutoff, TikTok captions short but keyword-rich, and Threads under 200. Getting the first line right matters more than total length.
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