Why the 150-Character YouTube Description Rule Is Wrong... and How to Nail It Every Time

Your YouTube description can hold 5,000 characters. Most viewers will see only a small slice of it.

Everything else sits behind "...more," and many viewers never click it. For them, the first few lines are your description.

So how much space do you actually get? Search for that and you'll keep running into the same answer, often called the 150-character rule: only the first 150 characters or so of your description show before it's cut off, so put everything important there. Some guides say 100 characters, some say 157, but the idea is the same: a fixed number you can write to.

It's simple, memorable advice. It's also wrong. We tested it on desktop and mobile, and the same description showed anywhere from zero to about 521 characters, depending on the screen.

Here's what's really going on, and how to write an opening that works everywhere.

(Looking for what to include in the rest of your description? See What to Put in a YouTube Description.)

Why the first three lines matter

Those few lines above "...more" are the only part of your description viewers see without asking for more.

They're all many viewers ever read. Everything below "...more" only reaches viewers who choose to expand it. For everyone else, your opening lines are the whole description.

They're where your most important links get seen. An affiliate link, a sponsor's link, your product, your newsletter signup, your next video: a viewer can't click a link they never see. If the link matters, put it in the space above "...more."

They tell viewers they're in the right place. Your opening lines sit right under the video while it starts playing. A clear line about what the video covers, or what viewers will get from it, backs up the promise your title and thumbnail made.

Get these lines right and they can do real work for your channel before a viewer ever clicks "...more."

There's no magic number

We published one test description and checked how much of it showed before the cutoff on different screens. Same text every time:

The same description went from nothing at all to more than 500 characters. On desktop alone, just resizing the browser window more than doubled what viewers could see.

That's because the fold isn't a character count. On desktop, YouTube gives your description a box exactly three lines tall. Whatever fits in that box shows, and everything else gets cut off. How much fits depends on two things: how wide the box is, and what you put in it. A heading is taller than regular text and fills the box faster. A blank line uses up a full line.

Even the letters you use change the math. In another test, three lines of the same width held 67 uppercase letters, 85 lowercase letters, or 75 mixed characters. No character rule can account for that.

Browser zoom changes it too. Zooming in fits fewer words on each line, and zooming out fits more, but it's always three lines.

What viewers see on desktop

On a desktop watch page, the collapsed description shows three lines of text, below the view count and upload date.

• The width of those lines depends on the browser window. A wide window fits far more words per line than a narrow one.
• The last line is shorter than the others. "...more" takes up the end of it, and the text fades out just before it.

What viewers see on mobile

The YouTube mobile app works in two steps.

Step 1: the watch screen. Below the video, viewers see your title, a short stats line, and "...more." None of your description shows here. On mobile, your title does the job your opening lines do on desktop.

Step 2: the description panel. If a viewer taps to open it, they see about six lines of your description (on our test iPhone) before it fades into a "See more" button. That's more lines than desktop, but each line is much shorter.

So which should you optimize for? Desktop, and specifically a narrow browser window. There's nothing to optimize on the mobile watch screen, since your description is hidden behind a tap. Once the description is open, the narrow desktop view is the tightest spot your opening has to work in. An opening that works there fits comfortably in the mobile description panel too. It doesn't work the other way: an opening written for the mobile panel's six lines gets cut off on desktop.

What eats into your preview

Blank lines. A blank line between paragraphs counts as one of your lines. On desktop, a single blank line after your first sentence throws away a third of your preview. Adding more doesn't make it worse, since YouTube collapses any run of blank lines down to one, but that one still uses up a full line.

Headings. Headings are larger text, so they use up the preview faster. In our narrow desktop test, a heading at the top filled the entire preview on its own. On mobile, a heading took three of the panel's six lines. Headings are hard enough to predict that even our own formatter warns you when one shows up in your opening lines. The simplest fix is to keep them out of it.

Things that don't cost you preview lines:

• Hashtags. The three hashtags YouTube shows at the top of the description sit on the same line as the view count, so they don't push your text down.
• Blank lines at the very top. YouTube deletes them when you save.

The better rule: think in lines, not characters

Forget character counts. On the narrowest desktop view, you get three lines, and every choice you make spends them:

• A line break ends a line early, even if the sentence before it is short.
• A blank line uses up a whole line.
• A heading uses up more than one line.

So instead of asking "is this under 150 characters?", ask: "does my most important point fit in the first three lines of a narrow browser window?"

Why you can't check this in Studio

The description box in YouTube Studio doesn't show where the fold falls. We tested this: when we widened the browser window, Studio's box went from 18 to 19 words per line, while the watch page jumped from 18 to 43. You're writing in a box that can't show you what viewers will see.

How to nail your opening every time

1. Write for a narrow desktop window. It's where your visible description has the least room to work. Get those three lines right first.
2. Put what matters most in your first sentence, and front-load it. Your first sentence gets the best shot at being seen. Put the most important words at the start, in case the sentence runs past the fold.
3. Don't put blank lines in your opening. Save paragraph breaks for after your first few lines. Every blank line up top costs you a line of preview on desktop.
4. Don't start with a heading. Open with plain text, and use headings for the sections below.
5. Put your most important link on the first or second line. Links are clickable in the collapsed preview, but a link on the third line can get cut off mid-URL. Keep it high up, and keep it short if you can.
6. Don't waste the opening on things viewers already know. Repeating your title, or lines like "Links below!", use up space that could be doing work.
7. On mobile, lean on your title. Mobile viewers won't see any description until they tap, so the title has to hook them first.
8. Check it before your video goes public. Paste your description into the free Description Formatter to see exactly where the fold falls. For a final check, upload the video as unlisted and look at the watch page at different window sizes and on your phone. You'll see exactly what viewers will see before anyone else does.

See where your fold falls before you publish

Studio can't show you where the fold falls, but the free TubeThink Description Formatter can. Paste in your description and see exactly what shows before "...more" in the narrow desktop preview, where your opening has the least room to work. It previews your formatting too, so you'll know your bold, headings, and lists will render the way you expect.

Try the free Description Formatter

(Need help with description formatting? Read YouTube Description Formatting: Hidden Features Most Creators Don't Know About.)