Reference

File size limits for every major platform

Every limit on this page was checked against the platform's own documentation. Each entry also explains the trap that actually makes an upload fail — which is usually not the headline number.

Last verified September 2026 · 18 platforms

Email attachment limits

Email is where size limits bite hardest, because the file is encoded before it is sent and that re-encoding inflates it by roughly a third.

Gmail

25 MB total per message

The 25 MB is the encoded message, not your file. Base64 encoding adds about 33%, so a 24 MB file can bounce off a 25 MB limit. Stay under about 18 MB raw for safety.

Source: Google Workspace support · Fix it: Compress files under 18MB

Outlook.com

25 MB attachment, 20 MB for internet email

Microsoft documents two different figures. The 20 MB figure applies to messages sent to external (non-Exchange) addresses, which is the one most people hit.

Source: Microsoft Support · Fix it: Shrink a document before sending

Yahoo Mail

25 MB per message

Same encoding inflation applies: a 20 MB file is the practical ceiling.

Source: Yahoo Help

Exchange / Microsoft 365 (default)

36 MB message size

Admins can change this, and many do. If a limit on your work account differs, your IT policy is the authority, not this table.

Source: Microsoft Learn

Messaging app limits

These vary enormously between the same app's photo, video and document modes — which is why the same file sends on one path and fails on another.

WhatsApp video (as media)

16 MB

Sending the same clip as a Document bypasses this almost entirely. WhatsApp also reduces video to 720p on the media path.

Source: WhatsApp Help Center · Fix it: Compress video under 16MB

WhatsApp document

2 GB

Documents are not re-compressed, so quality is preserved but the limit is far higher.

Source: WhatsApp Help Center

Telegram (free)

2 GB per file

Uploads are not re-compressed, so a sent file arrives byte-identical.

Source: Telegram FAQ

Telegram Premium

4 GB per file

Telegram documents the doubled upload limit as a Premium feature.

Source: Telegram Premium FAQ

Discord (free)

10 MB, recently raised toward 20-25 MB

This one is genuinely inconsistent right now: Discord's own support page says 20 MB, while many accounts still enforce 10 MB. Treat 10 MB as the safe figure.

Source: Discord Support · Fix it: Compress an image under 10MB

Discord Nitro (full)

500 MB

Nitro Basic sits at 50 MB. Verify against your current plan before relying on it.

Source: Discord Nitro FAQ

AI tool upload limits

These changed fast through 2025 and 2026, and they are the limits people most often get wrong when they try to hand a large document to a model.

ChatGPT

512 MB per file

Text documents are additionally capped around 2 million tokens, so a large PDF can fail on content rather than on bytes.

Source: OpenAI Help Center · Fix it: Reduce a PDF before uploading

Claude

30 MB per file

Roughly 17 times smaller than ChatGPT's ceiling, which is the single most common surprise when switching between the two.

Source: Anthropic Support

Gemini

Varies by surface

Limits differ between the web app, the API and Workspace, and they change frequently. Check the current figure in-product rather than trusting a third-party table.

Source: Google Gemini Help

The limits that are not officially documented

These are not written down by any vendor, but they are real and they break uploads more often than the documented caps do.

Web form upload fields

Often 2 MB, sometimes as low as 100 KB

Set by whoever built the form, not by a platform. Government and university portals are the most restrictive, and they rarely state the number until your upload fails.

Source: MDN: HTML file input (no default limit exists) · Fix it: Compress an image under 200KB

Passport and visa photo uploads

Typically 20 KB to 240 KB by country

Every country sets its own dimensions and byte range. Compressing to the byte target is only half the job; the pixel dimensions and aspect ratio must match too.

Source: US State Department (one example; check your own country) · Fix it: Compress a photo to an exact size

Why an upload fails even when you are under the limit

Most failed uploads are not caused by the number in the table. The three usual causes:

Encoding inflation. Email encodes attachments before sending, which adds about a third to the size. A 24 MB file becomes roughly 32 MB on the wire and bounces off a 25 MB limit.
The limit belongs to the form, not the platform. Web forms set their own cap, often 2 MB and sometimes 100 KB. Nothing in the page tells you the number until your file is rejected.
Dimensions and duration trip first. A photo can be under the byte limit and still fail because its pixel dimensions or aspect ratio do not match the requirement.

If your file keeps getting rejected, compress it to a byte target rather than a quality setting — compress an image, compress a PDF, or compress a video and check the result against the limit above.

Limits change without notice, and vendors rarely announce it. Every figure above was checked against the linked source when this page was last verified. If you find one that has moved, the source link is the authority — and we would rather be corrected than keep publishing a stale number.