YouTube SEO guide: titles, descriptions, tags, thumbnails and chapters

YouTube SEO is the work that helps your video meet the right viewer both in YouTube search and in recommendations. There's no magic keyword or trick; in YouTube's own words, search ranking rests on three things: relevance, engagement and quality. In this article we turn each into practice.

How does YouTube rank search results?

According to YouTube's explanation of search, ranking is based on these signals:

• Relevance: how well the title, tags, description and video content match the search query.
• Engagement: overall viewer engagement, such as the watch time of a video for a particular query.
• Quality: signals that help determine which channels show expertise, authoritativeness and trustworthiness.

Results can also differ by a person's search and watch history, so not everyone sees the same ranking for the same query.

1. Choose the keyword in the viewer's language

Find the phrase the viewer really types: the autocomplete suggestions in the YouTube search box, Google Trends and the Research (Trends) section of YouTube Studio are good starting points. After picking a word, look at the results for that query: the format, length and angle of the top videos show what the viewer expects. For detailed methods see how to find video topics.

2. The title

• Limit: up to 100 characters (YouTube API docs); in practice focus on about 60 characters.
• Main keyword first: like "How to make YouTube Shorts: length and size guide".
• Make the promise clear: spark curiosity but don't misrepresent the video; a misleading title loses viewers fast and can turn into a policy violation.
• One video, one promise: don't squeeze five unrelated topics into one title.

3. The description

The description field can be up to 5,000 bytes. Do this:

• Write the topic and the main keyword naturally in the first 2–3 lines; that part is visible in search results and before "show more".
• Add your sources, related videos and links.
• Add chapters with timestamps (see below).
• Don't keyword-stuff.

4. Tags and hashtags

YouTube says it plainly: tags can be useful if your content is commonly misspelled; otherwise they play a minimal role in discovery; title, thumbnail and description matter more (YouTube Help). The total length of tags is limited to 500 characters and stuffing tags into the description violates the spam policy. Be moderate with hashtags: YouTube shows up to three of the most engaging hashtags above the title; excessive use may cause hashtags to be ignored and the content to be removed from search. 3–5 relevant hashtags are enough.

5. The thumbnail

The thumbnail directly affects click-through rate. YouTube's requirements:

• 16:9 aspect ratio for videos, at least 640 pixels wide (up to 3840×2160). 9:16 vertical for Shorts thumbnails.
• JPG or PNG; up to 50 MB from desktop and 2 MB from mobile.
• Your account must be verified for a custom thumbnail.

Design tips: one focal point, few words (3–4), high contrast, legibility at a small size and fit with the video's promise. A misleading thumbnail backfires by raising clicks and lowering watch time.

6. Chapters

If you add timestamps to your video's description YouTube can divide the video into chapters. The rules (YouTube Help): at least three timestamps in ascending order; the first must start at 00:00; each chapter must be at least 10 seconds. Chapters make it easy for viewers to jump to what they want and can increase retention in long videos.

7. Retention: the strongest SEO signal

Relevance alone isn't enough; if viewers don't keep watching you can't stay in the rankings. Focus on: showing the promise in the first seconds, cutting needless intros, keeping visual tempo lively and pointing viewers to a related video at the end. We explain how to read these signals in the analytics guide.

8. What differs for Shorts

Shorts are mostly discovered through the recommendation feed rather than search, so the first second and retention are decisive. Still, putting the main keyword naturally in the title and description helps search visibility (Shorts guide).

Pre-publish SEO checklist

• [ ] Is the main keyword a phrase viewers really search?
• [ ] Is the main keyword at the start of the title, and is the promise clear and honest?
• [ ] Do the first lines of the description explain the topic?
• [ ] Is the thumbnail 16:9, legible and true to the promise?
• [ ] Are chapters (in long videos) entered correctly?
• [ ] Are tags and hashtags moderate?
• [ ] Does the first 10 seconds of the video deliver the promise?

Automating SEO

Generating titles, descriptions and tags can be handed to AI, but reading the result stays with you. Mecra produces a title and description that fit the topic for each video, creates a thumbnail and enters them into YouTube at upload. Still, review the output yourself on the first videos and adjust it to your brand's tone.

Sources

• How YouTube ranks search results (YouTube Help)
• Video details and tags (YouTube Help)
• Custom thumbnails (YouTube Help)
• Video chapters (YouTube Help)
• Videos: resource properties (YouTube Data API)