Ideal Post Length & Reading Time for Social Media
Character limits and realistic read times for the platforms that matter.
Quick answer: most social captions read in under 15 seconds. LinkedIn posts that outperform tend to run 150-300 words (about 40-80 seconds at 238 WPM); X/Twitter and Instagram captions perform best well under 30 seconds.
Platform-by-platform limits and read time
| Platform | Character limit | Engagement-friendly length |
|---|---|---|
| X (Twitter) | 280 (25,000 for Premium) | ~70-100 characters, <10 sec read |
| 3,000 | 150-300 words, ~40-80 sec read | |
| Instagram caption | 2,200 | 125-150 characters visible before "more", ~10 sec |
| Facebook post | 63,206 | 40-80 words performs best, ~15-20 sec |
| Threads | 500 | Under 100 words, ~15-25 sec |
Why shorter usually wins on social
Social feeds are skimmed at a much faster effective rate than articles — readers decide whether to engage within the first line or two, so the "reading time" that matters is really the time to the first hook, not the whole post. LinkedIn is the notable exception: longer, story-format posts (150-300 words) with a strong first two lines often outperform short ones because the algorithm favors dwell time within the post itself.
Using ReadMetric for social copy
Paste a caption draft into the calculator's Reading Time tab with the Skimmer persona (350 WPM) selected — it approximates how fast a scrolling feed reader processes text, closer to real social-reading behavior than the default Casual pace.