YouTube Upload Checklist: Thumbnail, Chapters and Subtitles

Before publishing a video on YouTube it is worth running through a short list: a title of 100 characters at most, a useful description, a custom thumbnail, chapters with the first timestamp at 00:00, subtitles in a compatible file, the AI disclosure if the content is realistic, and the indication of whether the video is made for kids. This checklist covers each point with what YouTube's official help pages say and what is worth checking yourself.

Before uploading: the finished video

The checklist starts before you open YouTube Studio. Watch the whole video one last time, with headphones and at normal speed, and check:

• That the audio sounds equally loud from start to finish, with no cuts or odd silences.
• That the facts in the script have been checked and no claim is left without a source.
• That you hold the licence for every image, piece of music or clip that is not yours.
• That it is the final version and not an earlier preview.

Title and description

According to YouTube's page on video settings, titles have a limit of 100 characters and descriptions a limit of 5000; neither can include invalid characters.

• Title: it should say what the video is about and deliver what it promises. Put the important words first, so it still makes sense if it is shown truncated.
• Description: the first two lines summarise the video; after that, the sources, the links and, if you use them, the chapters.

Custom thumbnail

YouTube lets you choose one of the thumbnails it generates automatically or upload your own if your account has been verified. Custom thumbnails are among the intermediate features, which you can access by verifying your phone number.

For custom video thumbnails, the official page on thumbnails recommends:

• A resolution of 3840x2160 pixels, with a minimum width of 640 pixels.
• JPG or PNG format.
• A 16:9 aspect ratio.
• Staying within the size limit for each device: 2 MB for video thumbnails if you upload from a phone and 50 MB from a computer.

All custom thumbnails must comply with the Community Guidelines, and a channel can upload only a limited number per day. Check for yourself that it reads well when small: look at it at the size it appears on a phone and remove text if it cannot be understood.

Chapters

Chapters divide the video into sections and help viewers go back to a specific part. To add them yourself, YouTube's help page on chapters asks for:

• A list of timestamps and chapter titles added to the description.
• The first timestamp in the list starting at 00:00.
• At least three timestamps in ascending order.
• No chapter shorter than 10 seconds.

If you do not yet have access to chapters, you need to request access to advanced features. And bear in mind that if you add chapters in the description, the automatic chapters are overridden.

Subtitles

Subtitles help your videos reach more people, including people who are deaf or hard of hearing and those who do not speak your language. A subtitle file contains the text of what is said and the timestamps that show when each line appears.

• If you have never created one, YouTube recommends the SubRip (.srt) or SubViewer (.sbv) formats.
• In those formats, style information is not recognised, and the file must be in UTF-8 with no formatting.
• You can add the subtitles during the upload or afterwards, from the subtitles section of YouTube Studio.

YouTube also creates automatic subtitles using speech recognition. If you use the automatic ones, check them before accepting them, especially proper names and figures.

AI disclosure and audience

There are two declarations that should not be left until the end:

• AI use. YouTube requires creators to tell the audience when content that looks realistic has been generated or altered with AI. You indicate it in the “Attributes” section, under “AI use”, choosing Yes or No. According to the page itself, acknowledging that content was generated with AI does not limit the video's audience or affect monetisation. You will find examples in the synthetic content label on YouTube.
• Audience. YouTube asks you to indicate whether your videos are made for kids, a decision worth taking carefully.

The checklist, as a list

1. Final video reviewed in full, with audio and licences in order.
2. Clear title of 100 characters at most.
3. Description with summary, sources and links.
4. Custom thumbnail in 16:9, legible when small.
5. Chapters: the first at 00:00, at least three, none shorter than 10 seconds.
6. Subtitles in .srt, checked.
7. AI disclosure ticked if the content is realistic and has been generated or altered with AI.
8. Audience indicated.
9. After publishing, note down the link and look at the figures again calmly: in how much it costs to make a video with AI we explain how to compare them with what it cost.

What the Estudio de Canales prepares

The Estudio de Canales does not publish for you: it prepares a package for you to upload by hand in YouTube Studio. That package contains the video, three thumbnails, the subtitle file, the title, the description, the chapters, the metadata and a licences file. In addition:

• The subtitles come from the approved script and the real audio duration of each scene, not from estimates.
• The chapters come from the script sections and are validated against YouTube's rules: the first at 00:00, at least three, and at least 10 seconds long. If they are not met, it says why and leaves them out.
• The title is checked so that it does not exceed 100 characters.
• The three thumbnails are composed over the scene visuals, with the text in the studio's own typeface, and their legibility at 168×94 and their contrast are checked. They come out at 1280×720 pixels: 16:9 and above the minimum width of 640 pixels, but below the 3840x2160 pixels YouTube recommends.
• If there is synthetic content, the disclosure comes ticked and the description says so.
• Before preparing the package, the studio decides whether the video is ready to publish: anything mandatory blocks it, while advisable items, such as the description, the chapters or the AI declaration, only trigger a warning.

Once you have uploaded it, you paste the link into the studio; if the channel is linked, it checks with YouTube that the video belongs to that channel and the studio tracks its figures.

Sources consulted

Checked on 9 October 2026. We link to the original source so that you can consult the current text.

• Cambiar la configuración de vídeo. Google · Ayuda de YouTube.
• Añadir miniaturas personalizadas en YouTube. Google · Ayuda de YouTube.
• Acerca del acceso a las funciones por parte de creadores de YouTube. Google · Ayuda de YouTube.
• Capítulos en vídeos. Google · Ayuda de YouTube.
• Añadir subtítulos. Google · Ayuda de YouTube.
• Archivos de subtítulos y subtítulos opcionales compatibles. Google · Ayuda de YouTube.
• Avisar sobre el uso de contenido generado por IA. Google · Ayuda de YouTube.