File size limits for email and messengers
Attachment and upload limits of Gmail, Outlook, Yahoo, iCloud, WhatsApp, Telegram, Discord, Slack and others, checked against their help pages.
Attachment and upload limits at a glance
The table lists the limits that the services themselves publish in their help pages. We checked every entry on October 22, 2026. Services change these numbers from time to time, so the source for each one is linked below the table.
| Service | Limit | What it applies to |
|---|---|---|
| Gmail (personal account) | 25 MB | All attachments of one email; above that, Gmail inserts a Google Drive link instead |
| Gmail (Google Workspace) | Set by the administrator | Work and school accounts |
| Outlook.com | 25 MB | The whole email, including text and inserted images; OneDrive links to files up to 2 GB do not count |
| Outlook desktop app with IMAP or POP accounts | 20 MB | Default limit for all attachments together |
| Microsoft 365 work or school mail | 35 MB to send, 36 MB to receive (default) | Administrators can set 1–150 MB; Outlook on the web allows about 25 % less than the setting |
| Yahoo Mail | 25 MB | All attachments of one message, sent or received |
| iCloud Mail | 20 MB (up to 5 GB with Mail Drop) | The whole message; Mail Drop links stay available for 30 days |
| Proton Mail | 25 MB to send, 50 MB to receive | All attachments of one message, up to 100 files |
| 2 GB for documents; videos 100 MB at 720p by default | On slower connections the default video limit is 64 MB at 480p | |
| Telegram | 2 GB per file (4 GB with Premium) | Any file type |
| Discord | 20 MB without Nitro; 50 MB with Nitro Basic; up to 1 GB with Nitro | Per file; the free limit was raised from 10 MB in August 2026 |
| Slack | 1 GB | Per file, for members and guests on all plans |
Sources
- Gmail: https://support.google.com/mail/answer/6584 (opens in a new tab)
- Outlook.com: https://support.microsoft.com/en-us/outlook/sending-limits-in-outlook-com (opens in a new tab)
- Outlook desktop app: https://learn.microsoft.com/en-us/outlook/troubleshoot/message-body/attachment-size-exceeds-the-allowable-limit-error (opens in a new tab)
- Microsoft 365: https://learn.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits (opens in a new tab)
- Yahoo Mail: https://help.yahoo.com/kb/SLN5673.html (opens in a new tab)
- iCloud Mail: https://support.apple.com/en-us/102198 (opens in a new tab) and Mail Drop: https://support.apple.com/en-us/108329 (opens in a new tab)
- Proton Mail: https://proton.me/support/attaching-multiple-documents-to-a-message (opens in a new tab)
- WhatsApp: https://faq.whatsapp.com/453914586839706 (opens in a new tab)
- Telegram: https://telegram.org/faq (opens in a new tab)
- Discord: https://support.discord.com/hc/en-us/articles/25444343291031-File-Attachments-FAQ (opens in a new tab)
- Slack: https://slack.com/help/articles/201330736-Add-files-to-Slack (opens in a new tab)
Why a file is rejected even though it is below the limit
Email was designed for text, so attachments are converted to text (Base64 encoding) before they are sent. That makes them about a third larger in transit. Microsoft states the increase as 33 %, and Proton warns that encoded files are slightly larger than on your device. As a result, a 24 MB attachment can be too big for a 25 MB limit. A few more things to keep in mind:
- The limit is usually per message, not per file. Five 6 MB photos together exceed a 25 MB limit.
- The recipient's limit counts too. You may be allowed to send 25 MB, but the receiving company server may accept only 10 or 20 MB and bounce the message.
- Work accounts differ. In companies, schools and universities, the administrator decides, and the limit can be lower than the public number.
A practical rule for email: keep the total of all attachments at roughly three quarters of the official limit. For a 25 MB service, aim for 18 MB or less.
Which tool to use to get under a limit
- Photos too big for email: the image compressor resized to 1920 px on the longest side at quality 75 usually brings phone photos to a fraction of their size, so many fit into one message.
- A video for email or Discord: the video compressor with a target size, for example 18 MB for email or 19 MB for the free Discord limit, and 720p for longer clips.
- A scanned document for an online application: the PDF compressor with the Recommended preset, or Strong if the portal allows only a few megabytes.
- A presentation for a course platform: the PowerPoint compressor, which recompresses the photos inside the slides.
- A long voice recording: the audio compressor in mono at 64 kbps, about 29 MB per hour.
Upload forms on websites
Job portals, university applications, government services, insurance claims and online shops set their own limits, often much lower than email: a few megabytes per file is common, and some forms accept only certain formats such as PDF or JPG. The form or its help text usually states the limit. Compress to clearly below it, because some forms measure in mebibytes (1 MiB is 1,048,576 bytes) and others in decimal megabytes, and the two differ by almost 5 %.
If a form asks for a single PDF and you have several scanned pages, combine them first in your scanner app or PDF reader, then compress the combined file.
When a link is the better choice
Some files should not be squeezed into an attachment at all: a full-length video in good quality, a photo collection for printing, raw recordings for an editor. For these, the built-in cloud links of the services in the table are designed for exactly this: Google Drive in Gmail, OneDrive in Outlook, Mail Drop in iCloud Mail. Messengers such as Telegram and WhatsApp also accept files up to 2 GB as documents, without recompressing them. Compressing is the right choice when the recipient needs the file itself in their inbox or the platform simply has a size limit.