Signal Specifications

Shared Image

Max File Size	200 MB
File Formats	JPG, PNG, GIF, WEBP
Notes	Images shared in chats are compressed by default; original quality option available

Profile Photo

Dimensions	Scaled to max 640 × 640 px
Aspect Ratio	1:1
Max File Size	5 MB
File Formats	JPG, PNG
Notes	Displayed as a circle; visible only to your contacts

Sticker Pack

Dimensions	512 × 512 px per sticker
Max File Size	300 KB per sticker
File Formats	PNG, WebP, APNG
Notes	Custom sticker packs can be created and shared; max 200 stickers per pack

Shared Video

Max File Size	200 MB
File Formats	MP4, MOV, AVI
Notes	Videos are end-to-end encrypted; compressed for delivery; attachment limit doubled from 100 MB to 200 MB in September 2025

Voice Message

File Formats	AAC, MP3
Max Duration	Up to 5 minutes per clip
Notes	In-app recorded voice note; plays directly in chat

Video Call

Resolution	Up to 720p
Notes	End-to-end encrypted 1:1 and group video calls; up to 75 participants

Message

Character Limit

No practical limit

Notes

Signal supports very long text messages; no documented hard cap. Re-verified this pass by inspecting Signal-Android's current open-source code directly (github.com/signalapp/Signal-Android, main branch): the main chat compose box (ComposeText.java) has no InputFilter/length cap applied to message text — confirms no client-enforced hard limit on ordinary messages today. Other text-entry surfaces in the same codebase DO have explicit caps, for context: MAX_BODY_DISPLAY_LENGTH = 1000 (just a 'read more' truncation point in the conversation list UI, not a send limit), MAX_CAPTION_SIZE = 1500 (media/attachment captions), MAX_TEXT_STORY_SIZE = 700 (Stories text posts) — none of these apply to regular 1:1/group chat messages. Historical note: a 2018 Signal-Desktop GitHub issue (#2004) was confirmed by then-Signal engineer Scott Nonnenberg as a real limitation in the Signal Android client of that era (~2000 characters, with Desktop warning the sender), but this predates Signal's later removal of SMS/MMS interop and is not reflected in the current source. Conclusion: still no documented/enforced hard cap, now backed by direct source inspection rather than absence of evidence

Profile Name

Character Limit	26 characters per field
Notes	First name and last name are separate fields, 26 characters each

Profile About

Character Limit	140 characters

Group Name

Character Limit	32 characters

Profile Photo

Dimensions	Scaled to max 640 × 640 px
Max File Size	5 MB
File Formats	JPG, PNG
Notes	Visible to contacts; displayed as a circle