On Mastodon, you can attach up to four images, or one video file, or one audio file when making a post. Click on the paperclip 📎 or landscape 🌄 icon to attach something to your post.
- Images can be PNG, JPG or GIF (including animations). The maximum file size is usually 8mb per image.
- Video clips can be MP4, M4V, MOV or WebM files. The maximum file size is usually 40mb, but there is no limit on running time.
- Audio clips can be MP3, OGG, WAV, FLAC, OPUS, AAC, M4A or 3GP files. The maximum file size is usually 40mb, but there is no limit on running time.
File size limits may vary on different servers, but these are the defaults. Ask your server admin if you have problems with uploads. Note that if your server is unusually busy (for example if there are unprecedented numbers of new users signing up all at once) then file uploads may slow down or stop for a while.
Remember to add text descriptions to attached files before posting, so that they can be accessible to people with disabilities. You can do this by clicking Edit on the file before posting, or writing on top of the file itself on the official apps. For video clips, remember to describe both the audio and video, so that both deaf and blind people are able to find out what’s going on.
There is no GIF picker on Mastodon due to the federated nature of the Fediverse. However, if you post a link to GIF it will automatically be embedded when you post it, as if the GIF had been chosen from a picker. Alternatively, if you have the actual GIF file stored on your computer or phone, you can upload it as an image.