Table of Content
Posting the same idea across Instagram, TikTok, LinkedIn, X, YouTube, Facebook, and Threads sounds like one task. In practice it turns into seven. A graphic gets designed, uploaded to one app, cropped by the feed, fixed, then rebuilt for the next platform until an afternoon disappears.
Most of that work is avoidable. The fix is boring and specific: stop treating “post it everywhere” as a single job and start treating each feed as its own frame with its own rules. Once the numbers are memorized and the export routine is fixed, a task that used to take two hours drops to about twenty minutes. Nothing gets cropped, nothing gets truncated at the worst possible word, and reach on the vertical formats climbs because the content finally fills the screen.
This guide is that routine, written down. Every dimension, character count, and length below reflects what the platforms actually enforce in 2026, not what they enforced two years ago. No filler, just the parts worth checking before a post goes live.
What “platform-ready” actually means
A platform-ready post needs zero fixing after upload. The image fills the frame instead of getting auto-cropped. The first line of the caption says something real before the feed hides the rest behind a tap. The video runs a length the algorithm will actually push. And the file is small enough, in a format the platform accepts without re-compressing it into mush.
Three things break more often than everything else combined: aspect ratio, caption truncation, and video length. Get those right and most of what makes a post look off is already solved. Here is the shape of the whole thing before the numbers.
Fills the frame Right aspect ratio, no auto-crop | Hooks first Line one lands before the fold |
Right length Shortest version that finishes the idea | Clean file sRGB, under the size cap, safe format |
The five master sizes that cover almost everything
This is the part that saves the most time. Fourteen separate image files are not necessary. Five master sizes cover roughly ninety percent of every placement across every network. Design at these, export once, and move on.
| Ratio | Size in pixels | Where it goes |
|---|---|---|
| 4:5 portrait | 1080 x 1350 | Instagram and Facebook feed posts. The 2026 default. |
| 9:16 vertical | 1080 x 1920 | Reels, Stories, TikTok, YouTube Shorts, Snapchat |
| 1:1 square | 1080 x 1080 | X, older feed layouts, carousel consistency |
| 1.91:1 landscape | 1200 x 630 | Link previews on LinkedIn, Facebook, X, Bluesky |
| Square profile | 400 x 400 | Every profile picture, the minimum for a sharp render |
A few things worth burning into memory. Instagram moved its profile grid to a taller 3:4 layout in January 2026 and now favors 4:5 portrait feed posts over squares, because portraits take up more screen and pull more reach. Design at double these numbers, so 2160 wide for a 1080 target, for crisp results on high-density screens, then export down. Keep files under 5 MB, export in sRGB so colors do not shift on upload, and reach for JPEG when in doubt. WebP is accepted on most platforms now, but JPEG remains the safe universal fallback.
Where a caption actually gets cut off
The character limit is not the number that matters. What matters is where the feed truncates the text, because most people never tap “more.” Treat the first line as the whole post, because for the scrolling majority, it is.
| Platform | Hard limit | Visible before the cut | Write for |
|---|---|---|---|
| 2,200 | about 125 characters | Hook in line one, details below | |
| TikTok | 4,000 | first line or two | Front-load searchable keywords |
| 3,000 | about 140 characters | One clear idea, expand under the fold | |
| X (free) | 280 | all of it | Say it once, cleanly |
| X (Premium) | 25,000 | about 280 | Short still beats long here |
| 60,000 plus | about 80 characters | Shorter posts win by a lot | |
| Threads | 500 | most of it | Conversational, one thought |
| Bluesky | 300 | all of it | Tight and direct |
Two details trip people up constantly. On X, every link eats exactly 23 characters of the 280 no matter how long the URL is, so plan around it. And TikTok quietly became a search engine, which is why its caption ceiling jumped to 4,000. Those extra characters are for the keywords the algorithm indexes, not for storytelling.
Video length: the maximum versus what works
Every platform allows longer videos than it rewards. The maximum a platform accepts and the length that actually gets pushed are two different questions, and confusing them is how good footage dies in the feed.
| Format | Maximum | What performs |
|---|---|---|
| Instagram Reels | up to 3 min recommended | 7 to 30 sec for reach, 30 to 60 for how-tos |
| TikTok | up to 10 min in app | 15 to 60 sec, longer only with a real payoff |
| YouTube Shorts | up to 3 min | One clear idea, fast |
| Instagram Stories | 60 sec per segment | Quick beats, keep it moving |
| X video (standard) | 2 min 20 sec | Under 60 sec |
The pattern holds everywhere. The best length is the shortest one that delivers the full idea. Instagram states outright that Reels over three minutes will not be recommended to new audiences, and its own engagement data favors clips under thirty seconds. Stretching a fifteen-second point to ninety seconds because the platform allows it works against reach. Let the retention graph choose future lengths, not a benchmark from a blog.
The one-asset-to-many workflow
This is the routine that turns two hours into twenty minutes. The trick is to build once at the largest safe canvas, then crop down, never up.
| 1 | Start vertical. Design the master at 1080 x 1920, the tallest frame needed. Keep every critical element, logo, text, and faces, inside the center 1080 x 1440 safe zone so nothing lands under the platform’s buttons. |
| 2 | Crop, do not rebuild. Pull a 4:5 at 1080 x 1350 and a 1:1 at 1080 x 1080 from the same master. Because the important content already sits in the center, both crops keep everything that matters. |
| 3 | Write the caption once, then trim per feed. Draft the long version, then cut a 125-character opener for Instagram, a keyword-loaded first line for TikTok, and a single sentence for X. Same message, three lengths. |
| 4 | Export in sRGB, under 5 MB, as JPEG or MP4. One color space, one format habit, no surprises when the platform re-encodes the file. |
| 5 | Check the fold before posting. Preview the first line and the first frame the way a scroller sees them. If the hook is not obvious in that sliver, fix it before anything else. |
Platform notes at a glance
The specs above cover the mechanics. These are the per-platform habits that decide whether a technically correct post actually performs.
Portrait is the whole game now. Post 4:5, land the hook in the first 125 characters, and treat Reels as the discovery engine while the grid holds the brand. Squares still upload but surrender screen space. | TikTok Write for search. The caption is indexed, so the first line should read like something a person would type into the box. The hook has to land in the first second. |
One idea per post, expanded under the “see more” fold. The first 140 characters carry the whole thing in the feed. A long story belongs in an article, not a post. | X Brevity is the format, not a limit to fight. Even Premium accounts see short posts outperform long ones. For anything longer, chain 240 to 280 character posts into a thread. |
YouTube Shorts One point, fast payoff. The first frame is everything, so make it obvious. Keep logos and text inside the safe zone so the interface does not cover them. | Facebook, Threads, Bluesky Facebook rewards the shortest posts, often under 80 characters with one strong image. Threads and Bluesky both reward a single conversational thought, not a formatted mini-essay. |
Mistakes that quietly cost reach
Each of these is easy to make and easy to fix once it is on the radar.
• Designing horizontal first. Building for landscape and cropping down to vertical throws away the safe zone and the engagement that comes with a full screen. Start tall.
• Putting text near the edges. Every vertical format reserves the top and bottom for profile chrome and the call-to-action bar. A logo or headline up there gets covered.
• Writing the caption for the limit instead of the fold. A 2,200 character Instagram caption is legal and mostly invisible. The first line does the work.
• Exporting in the wrong color space. Files saved in CMYK or Adobe RGB look washed out after the platform re-encodes them to sRGB. Set sRGB before exporting.
• Reusing one identical caption everywhere. The 280 character line that sings on X reads as clipped and thin on LinkedIn. Match the length to the room.
• Chasing a magic video length. There is no universal number. The right length is the shortest one that finishes the idea, and retention data tells the story.
The one-minute pre-publish checklist
Run this before every post. It takes about a minute and catches almost everything.
✓ Image fills the frame for the target format, no auto-crop ✓ Critical elements sit inside the center safe zone ✓ First line of the caption hooks before the “more” cut ✓ Caption length matches the platform, not the maximum ✓ Video is the shortest length that delivers the idea ✓ File is sRGB, under 5 MB or the platform cap, JPEG or MP4 ✓ Link accounted for, it costs 23 characters on X ✓ Previewed the first frame and first line the way a scroller sees them |
The final verdict
Platform-ready is a system, not a talent. Stopping the crops and the truncation does not take an eye for design or a feel for the algorithm. It takes five sizes, a handful of character counts, and the discipline to build vertical and crop down instead of rebuilding from scratch seven times. Keeping tables like these open in a second tab during a batch of content is worth the habit, and so is running the checklist before every post, because the platforms move the goalposts often enough that memory is not reliable. Instagram changed its grid in January. TikTok turned its caption into a search field. Something else will shift by next quarter. The numbers here are current for 2026, but the habit is what lasts: treat each feed as its own frame, respect the fold, and let the shortest version of the idea win. Do that, and the twenty-minute version of posting everywhere becomes normal. That is the whole trick, and it is a good deal less glamorous than the advice usually makes it sound. |