Compress video for email (Gmail 25 MB / Outlook 20 MB).
Gmail's own attachment figure, Outlook's message size, and the Exchange default are three different numbers. Make the sharing copy on this device.
Compress video for email (Gmail 25 MB / Outlook 20 MB)?
Gmail's own attachment figure, Outlook's message size, and the Exchange default are three different numbers. Make the sharing copy on this device. ✓ Gmail (consumer accounts): 25 MB maximum total attachment size before switching to Google Drive links ✓ Outlook.com and internet accounts: 20 MB message size, including the attachment and the message
Gmail Help: Send attachments with your Gmail message; Microsoft Support: reduce attachment size in Outlook
Last updated
Official email attachment limits and compression target
Official platform attachment constraints:
- Gmail (consumer accounts): 25 MB maximum total attachment size before switching to Google Drive links
- Outlook.com and internet accounts: 20 MB message size, including the attachment and the message
- Exchange default: 10 MB. A tenant administrator can change it
- RFC 2045 section 6.8 encodes every 3 bytes as 4 characters. Gmail Help does not publish a Base64 budget. The measured table on this page compares one file with 26214400, 20971520, 25000000, and 20000000 bytes.
Quality & local processing behavior:
- High-performance WebCodecs hardware encoding when supported by your browser
- Adaptive resolution ladder (1080p, 720p, 480p) maintains visual motion smoothness
- Your private video stays on your device and is never uploaded to CreatorPrivacyKit servers
How to compress and verify for email
Select your video
Drop your camera recording, presentation, or phone clip.
Preset applied
Choose Gmail at 25 MB or Outlook at 20 MB. The Outlook figure is a message size, so the file itself should sit under it.
Compress locally
Encode on-device using your GPU/CPU hardware acceleration.
Attach and send
Check the downloaded file against the mailbox you are actually using, then attach that copy.
Platform Facts & Email Field Notes
Gmail's help describes about 25 MB of attachments, then a Drive link. Microsoft's reduce-attachment article describes a 20 MB message size for Outlook.com and internet accounts, and a 10 MB Exchange default. Read the email field note for the same split.
Read Email Video Attachment GuideOne 20-second file against 20 MB and 25 MB, 27 October 2026
On 27 October 2026 this site built a 20-second MP4 with ffmpeg 6.1.1. Video is lavfi testsrc2, 1280 by 720, 30 fps, libx264 ultrafast, pix_fmt yuv420p, constant bitrate 12000k. Audio is a 440 Hz sine at 48000 Hz, AAC, requested 128k, with -shortest. The file is 28970764 bytes, SHA-256 3f0e6b046e55ddb06b822cef6d98a397225ca8296bf2f31c4506de05589ec6ce. ffprobe reported duration 20.000000, format bit_rate 11588305, H.264 video bit_rate 11452793, avg_frame_rate 30/1, and AAC bit_rate 127903. ExifTool listed CompressorName Lavc60.31.102 libx264, Encoder Lavf60.16.100, CreateDate 0000:00:00 00:00:00, and no GPS. The machine is a 13th Gen Intel Core i9-13900K running Linux 7.0.0-38-generic. The button on this page was not clicked. These files are ffmpeg encodes, not output from the in-browser compressor.
On this site a display megabyte is 1024 times 1024 bytes, from BYTES_PER_DISPLAY_MB in src/video-compressor/logic/targets.js. The email preset targetMb is 25. The outlook preset targetMb is 20. bitrateFromTargetSize takes targetBytes times (1 minus 0.02) times 8, subtracts the audio bits, and divides by the duration. CONTAINER_OVERHEAD is 0.02. AUDIO_BITRATE_AAC is 160000. For 20 seconds with audio, that function returns videoBps 8060836 and estimateOutputBytes 20963132 at 20971520 bytes, and videoBps 10116045 and estimateOutputBytes 26203915 at 26214400 bytes.
Two encodes used libx264 veryfast, with -b:v, -maxrate, and -bufsize set to those video bitrates, -c:a aac -b:a 160k, -pix_fmt yuv420p, and -movflags +faststart. ffprobe read the audio stream at 128073 bps on both outputs. A separate one-second mono sine encoded with the same ffmpeg and -b:a 160k reported 160 kb/s, Lavc60.31.102 aac. The 128073 figure is what these two files contain. Both outputs have duration 20.010000. The 20 MiB request is 19792403 bytes, SHA-256 8ee157a4717d737c71d25d09c18cd616315442c55e81d2dd725878383118ccde, format bit_rate 7913004, video bit_rate 7779620. The 25 MiB request is 24681475 bytes, SHA-256 65ed1824181dfe91dfeb9934ec5807694a9c9a933b444bcc5345e1f821c06955, format bit_rate 9867656, video bit_rate 9735249. Base64 character counts use 4 times ceil(n/3): 38627688, 26389872, and 32908636.
Gmail Help at https://support.google.com/mail/answer/6584, read on 27 October 2026, says the personal-account attachment limit is 25 MB, that a total over the limit becomes a Google Drive link, and that a Workspace administrator sets work and school limits. The same page says attachments count toward Google storage. It does not define MB as 1000 squared or 1024 squared, and it does not publish a Base64 budget. Microsoft’s reduce-attachment page says that for internet email accounts such as Outlook.com or Gmail the message size limit is 20 MB, that the Exchange default is 10 MB, and that the limit includes the attachment and the message. Microsoft’s Outlook.com sending-limits page says the attachment size limit is 25 MB and that a OneDrive link can go up to 2 GB. The two Microsoft pages disagree. This page keeps the lower published 20 MB figure for the Outlook preset. RFC 2045 section 6.8 encodes 3 bytes as 4 characters. In this table the 19792403-byte file is under both 20 MB definitions and both 25 MB definitions. The 24681475-byte file is under both 25 MB definitions and over both 20 MB definitions. The 28970764-byte source is over all four.
The signed columns are bytes over or under 20971520 (20 times 1024 times 1024), 26214400 (25 times 1024 times 1024), 20000000, and 25000000. The function estimates were 20963132 and 26203915. The files are smaller than those estimates. That comparison is the measurement. Pages that only restate the 25 MB and 20 MB help-center lines do not publish this file, these two requested video bitrates, or the probed audio rate of 128073.
Does Gmail’s 25 MB limit include a Base64 budget?
Gmail Help, read on 27 October 2026, says the personal-account attachment limit is 25 MB and does not publish a Base64 budget. RFC 2045 section 6.8 encodes 3 bytes as 4 characters. The 28970764-byte source is 38627688 characters in that encoding. The 19792403-byte encode is under both 20971520 and 20000000. The 24681475-byte encode is under both 26214400 and 25000000, and over both 20 MB figures in this table.
Frequently Asked Questions
What is the maximum video size for Gmail and Outlook?
Gmail personal accounts allow about 25 MB of attachments, and a larger total can become a Drive link. Outlook.com and internet accounts use a 20 MB message size that includes the attachment and the message. Exchange's default is 10 MB, and an administrator can change it. These are not one shared 25 MB cap.
Why should I compress before attaching instead of using cloud links?
Direct attachments do not require managing cloud file permissions, expiration dates, or third-party storage accounts, and can be viewed immediately by recipients.
Does compressing video for email upload my video?
No. The video is decoded and re-encoded locally inside your web browser using WebCodecs.