How to shrink a video for email and messaging apps

If a video won’t go through by email or a messaging app, first check the size limit where you’re sending it. Then save the video again one resolution step lower so it fits. That works because file size comes from bitrate and length, and a lower resolution lets you lower the bitrate too. This guide covers how to check limits, how to pick a quality level, and what to try if the file is still too big.

Check the limit where you’re sending it

Limits differ between services and can change. Check the service’s official help right before you send.

Sending to	Where to check	What it says
Gmail (personal account)	Gmail Help, “Send attachments with your Gmail message”	The limit is 25 MB. If the attachments add up to more, Gmail removes them and adds a Google Drive link instead (checked 2026-09-30)
Work or school email	Your administrator	Gmail Help says administrators set sending and receiving limits for work and school accounts
Messaging apps	The app’s official help center	Search for “send video” or “file size” to see the current rules
Other email services	Each service’s help pages	Search for “attachment size limit”

Some email services swap an oversized attachment for a link. If the recipient needs the file itself as an attachment, you have to get under the limit. And if the recipient uses a work account, remember there may be a separate limit on their side.

What sets the size: resolution, bitrate and length

Bitrate is the amount of data used per second. So a video’s size is roughly (video bitrate + audio bitrate) × length. Compress Video sets the bitrate from the resolution, so a lower resolution means a lower bitrate too. Here are the rules for its three Quality levels:

Quality	Resolution	Frame rate	Video bitrate factor	Audio
High	Kept as is	Kept as is	0.10	AAC 128kbps
Normal (default)	Long side up to 1280px	Up to 30	0.07	AAC 128kbps
Small	Long side up to 854px	Up to 30	0.05	AAC 96kbps

The video bitrate is width × height × fps × the factor. If that’s higher than the original’s, 80% of the original bitrate is used instead. The aspect ratio is kept, and videos smaller than the limit aren’t enlarged. For example, a 1920×1080 video becomes 1280×720 at Normal and 854×480 at Small. A portrait 1080×1920 video becomes 720×1280 at Normal.

A 30-second 1080p MP4 (H.264 + AAC, 5.8 MB) compressed at Normal came out at 1280×720 and 4.6 MB (−21%). (Measured in desktop Chrome; results vary by device and browser.) This test file already had a low bitrate, about 1.6 Mbps, so it only shrank a little. The higher the original bitrate, the more a video shrinks. At High, the same file stayed 1920×1080 and didn’t get smaller. The tool showed “This file is already optimized. We recommend keeping the original.” along with [Download original].

How to do it with ZEKILO Studio

Compress Video works inside this browser, and your file never leaves your device.

1. Drag and drop one video or pick it with [Choose files]. A preview appears along with the length, resolution and codecs.
2. Leave Quality at Normal (the default) for your first try, and press [Start]. The estimate below the options shows the resolution and approximate size, but the actual size may differ.
3. Compare the actual size on the result card with your limit, then save with [Download]. If it’s still over, try again with Small.

The result is always saved as an H.264 + AAC MP4, whatever the original format. It keeps the original name with -compressed added, as in clip.mov → clip-compressed.mp4. You can add one video at a time. We recommend up to 1 GB on desktop and 100 MB on mobile. Going over shows a warning, but you can still continue.

Still too big?

If the file is over the limit even at Small, try one of these:

• Make it shorter. Size grows almost in step with length, so keeping only the part you need makes it smaller. If your phone’s photo app can trim videos, cut the start and end first, then compress.
• Send a link. Some email services, like Gmail, turn an oversized attachment into a Google Drive link.
• Turn a short moment into a GIF. For a few seconds that don’t need sound, Video to GIF is an option. Clips can be up to 30 seconds, and there’s no sound. Making a GIF from the first 10 seconds of a 30-second 1080p MP4 at 10fps and 480px wide gave 480×270, 100 frames and 1.1 MB. (Measured in desktop Chrome; results vary by device and browser.) A GIF gets much larger as the clip gets longer, so keep it to short moments. For settings tips, see GIF settings that keep the file small.

If the video won’t play on the recipient’s device, the problem may be the codec rather than the size. MDN shows that browser support for HEVC depends on the operating system and hardware. Convert to MP4 can turn it into an H.264 MP4, and Compress Video always outputs H.264 as well. For more on this, see MOV vs MP4: what’s the difference.

Summary

• Check the limit in the service’s official help first. A personal Gmail account allows 25 MB, and anything bigger becomes a Google Drive link (checked 2026-09-30).
• Start Compress Video at Normal (long side 1280px). If that’s not enough, choose Small (long side 854px).
• A video with a low original bitrate won’t shrink much, so go by the actual size on the result card.
• If it’s still too big, shorten it, send a link, or turn a short moment into a GIF.