Social platforms each have their own dominant capitalization style. Posts that match the platform's native rhythm tend to perform better — both because they look right and because they signal that the writer understands the medium.
If you're managing brand presence across LinkedIn, X (Twitter), Instagram, TikTok, and Threads, you're effectively writing in five different dialects of capitalization. Here's how to think about each.
LinkedIn: title case for headlines, sentence case for posts
LinkedIn maintains a peculiar split: official profile sections use title case (job titles, company names, school names), but the body of posts and comments has shifted heavily toward sentence case.
Where to use title case on LinkedIn:
- Profile headline: "Senior Engineering Manager at Stripe" not "senior engineering manager at stripe"
- Job titles in experience: "Director of Product Marketing"
- Article headlines (the long-form publishing feature): "How I Built a Remote Team That Doesn't Burn Out"
- Newsletter titles: title case is the norm
Where to use sentence case on LinkedIn:
- Regular posts: "thinking about the future of work today..."
- Comments: sentence case is universal
- Most marketing copy: the modern LinkedIn tone is conversational
The mismatch — title case in your profile, sentence case in your posts — is the LinkedIn norm. Trying to enforce title case throughout reads as overly formal.
X (formerly Twitter): mixed, with a lowercase trend
X has the most varied capitalization conventions of any major platform because the post format is so short and the culture is so personality-driven. Three patterns are common:
Sentence case is the safe default. Most journalistic, business, and corporate accounts use sentence case. The Fed signaled rate cuts in 2026. This is also what Twitter's own UI text uses.
All lowercase is the dominant indie/personal-account style. thinking about how much the early internet was just personal websites. This style has become signal of authenticity in some communities — startup founders, designers, writers. It reads as intimate and unpolished, in a good way.
Title case is rare for original posts but common when quoting or referencing titled work. Just read "The Power Broker" by Robert Caro. Worth the 1200 pages. Title case in the original tweet text itself reads as old-fashioned or corporate.
For brand accounts on X, sentence case is the default and lowercase is a stylistic choice that requires commitment across the whole feed. Don't mix lowercase posts with title-case posts — pick one.
Instagram captions: sentence case with title-case taglines
Instagram captions are essentially short blog posts. Sentence case dominates:
- just got back from a week in Lisbon and I have thoughts.
- Three new arrivals this week — see them all in our latest drop.
- Sunday morning. Coffee and a slow start.
Hashtags break the rules — they have no spaces, so they form their own typographic system. Most use lowercase (#summer, #travel), but #PascalCase is also common (#WomenInTech) because it makes multi-word hashtags more readable.
Instagram's "branded" content — Reels titles, Story stickers, ad headlines — sometimes uses title case for the title-like elements while keeping the rest in sentence case. 5 Things I Learned as a Reel cover; Long-form thoughts below as the caption.
TikTok captions: lowercase or sentence case, never title case
TikTok's audience is younger and the platform culture leans heavily informal. Title case in a TikTok caption reads as out-of-touch or like a corporate account being run by someone over 50.
What works:
- tried the new recipe and it actually slaps (lowercase)
- POV: you're a software engineer in 2026 (sentence case)
- 3 things i wish i knew at 22 (lowercase with numerals)
What doesn't:
- Three Things I Wish I Knew at 22 (title case reads as wrong here)
For brand accounts on TikTok, lowercase is often the right call even if your other social channels use sentence case. It's the price of fitting in.
Threads: matches Twitter's sentence-case default
Threads (Meta's X competitor) has settled on a sentence-case norm similar to corporate X usage. Lowercase exists but is less prevalent than on X — the platform demographics skew slightly older and more brand-conscious.
Sentence case is the safest default for Threads.
Facebook: sentence case for posts, title case for events
Facebook posts use sentence case for body content. The exception is structured content like Events, which still use title case in the Event Name field. The platform has been around long enough that older conventions persist in the structured fields while the post body has drifted toward casual.
Pinterest: title case for pin titles, sentence case for descriptions
Pinterest is one of the few platforms where title case in original content is still the dominant style. Pin titles read like article titles, and SEO research suggests title case in Pin titles improves clickthroughs (this matches expectations on a platform that functions as a visual search engine).
- Pin title: 30 Easy Weeknight Dinners Your Family Will Love
- Pin description: Looking for quick dinner ideas? These 30 recipes are family-tested and take less than 30 minutes.
If you're producing Pinterest content, your Pin titles should look like blog-post titles. Title case is the norm.
YouTube video titles: title case dominant, but sentence case for casual creators
YouTube splits along channel type:
- News and publication channels: title case (looks like newspaper headlines)
- Educational and how-to channels: title case (looks like article titles)
- Personal vlogs and casual content: sentence case or all-lowercase
- Documentary-style longform: title case
For brands publishing on YouTube, title case is the default unless your brand voice is explicitly casual. How to Build a Garden Bed in One Weekend reads more authoritative than How to build a garden bed in one weekend.
Reddit: lowercase or sentence case depending on subreddit
Reddit's culture varies dramatically by subreddit. r/AskHistorians uses title case in post titles because it reads as scholarly. r/casualconversation uses sentence case. Some subreddits enforce title-case post titles via automod; most don't.
The safest default is sentence case for Reddit unless the subreddit you're posting in has visible title-case patterns in its top posts.
The platform-by-platform summary
| Platform | Default | Exceptions |
|---|---|---|
| Sentence case (posts) | Title case for headlines, articles, profile fields | |
| X / Twitter | Sentence case | Lowercase common for personal voice |
| Sentence case | Lowercase common; #PascalCase for hashtags | |
| TikTok | Lowercase | Sentence case acceptable; title case feels wrong |
| Threads | Sentence case | Less lowercase than X |
| Sentence case | Title case for Events | |
| Title case (pins) | Sentence case for descriptions | |
| YouTube | Title case (titles) | Sentence case for casual channels |
| Sentence case | Per-subreddit; some use title case |
The common mistake to avoid
The most visible social-media capitalization mistake is using the same style across all platforms when the platforms have different norms. If your brand publishes title-case posts on LinkedIn, sentence case on Threads, and lowercase on TikTok, that's right. If your brand publishes title case across everything, you'll look out of touch on TikTok and over-formal on Instagram.
The other mistake: applying English-language title-case rules to non-English content. German, French, Spanish, and most other European languages don't capitalize the same words English title case does. Don't translate your English title-case rules onto translated posts.
Tools that help
If you're managing posts across platforms, our case converter can quickly switch a piece of copy between title case and sentence case so you can see what it looks like under each. The bulk converter handles batches if you're scheduling many posts at once.
For hashtag generation, the slug or kebab-case modes produce platform-friendly tag candidates (though hashtags use no separators — strip them after conversion).