Get your video attachment under Gmail's limit
Drop a video and FitSize shrinks it to what Gmail will really accept, in your browser. Nothing is uploaded to a server.
Instant client-side compression · Up to 2 GB per file · Zero server upload
- Current limit
- 25 MB
- FitSize aims for
- 18.1 MB (room for email encoding)
- Last checked
- 30 September 2026
- Read on
- support.google.com
Gmail gives you an attachment limit, you attach a file that looks comfortably under it, and it still fails or turns into a Drive link. The number on the box is not the number that matters: what travels is the encoded email, and encoding adds weight. This page explains the gap and aims for the size that actually goes through.
Why Gmail has this limit
Why does Gmail reject large file attachments? Gmail enforces a strict 25 MB limit per message, and MIME base64 encoding adds approximately 33% overhead to raw files. FitSize uses the W3C WebCodecs API to deterministically shrink attachments under safe thresholds with zero-byte server upload privacy.
Gmail's help page does not explain why an attachment that looks under the limit can still be refused. The reason is how email works: attachments are encoded to travel as text, which makes them bigger. Proton documents that encoding makes attached files a bit larger than on your device, and Fastmail says an email under 70 MB usually means an attachment of no more than 50 MB. FitSize applies the same reasoning to Gmail.
Our reasoning, from proton.me , fastmail.help , support.google.com
What FitSize does with your file
FitSize does not aim for the number on the box. It leaves room for the encoding and for the message itself, and shows you the real usable size, so a file it produces is one Gmail will actually send. If the recipient's provider has a smaller limit than yours, check the sibling pages linked below, because the smallest limit in the chain is the one that decides.
Best fit for a 30-second clip at 18.1 MB: 720p at Balanced quality (that resolution holds up to 59 s). Best fit for a 2-minute clip at 18.1 MB: 480p at Balanced quality (that resolution holds up to 2 min 05 s).
Your file never leaves your device. It is read and compressed by your browser, and nothing is uploaded to a server.
Three things to watch on Gmail
- The limit is applied to the encoded message. Gmail does not say whether its limit counts the encoded message. Email attachments travel base64-encoded, about 37% larger once line breaks are counted, so FitSize treats the limit as covering the encoded size and aims for 18.1 MB, not the full limit. Our reasoning, from proton.me , fastmail.help
- Over the limit, Gmail sends a Drive link. When your total attachment size is greater than the limit, Gmail automatically removes the attachment and adds it as a Google Drive link in the email, and Google recommends Drive for particularly large files such as videos. Source: support.google.com
- Work accounts and the recipient can change the answer. For Google Workspace accounts the administrator sets the attachment sending and receiving limits, so the personal-account number may not apply to you. The recipient's provider matters too: iCloud Mail allows 20 MB per message and Yahoo Mail 25 MB of attachments. Source: support.google.com , support.apple.com , help.yahoo.com
FitSize vs traditional cloud converters
| Architecture Feature | FitSize (In-Browser) | Traditional Cloud Converters |
|---|---|---|
| Latency | Instant / 0s queue delay | 15–45s upload queue & network delay |
| Privacy | 0-Byte Server Upload (100% on-device) | Files uploaded & stored on third-party servers |
| Bandwidth | 0 MB upload bandwidth consumed | Full upload and download bandwidth consumed |
| Exact File Size Guarantee | Deterministic bit-budget target | Trial-and-error guesswork re-compression |
Frequently asked questions about Gmail compression
What is the maximum attachment size allowed in Gmail?
Gmail allows up to 25 MB in total message size. However, because email protocols encode binary files into base64, files larger than roughly 18 MB can trip the 25 MB message limit.
How do I send a video via Gmail without Google Drive links?
Use FitSize's Gmail preset to shrink your video or document under 18 MB. This fits comfortably within Gmail's base64-encoded transmission envelope without converting your attachment into a Google Drive link.
Are confidential business attachments safe with FitSize?
Yes. FitSize operates strictly on your local machine using the W3C WebCodecs API. Your documents and attachments are never uploaded to any external server or cloud database.