How to divide a video to fit under email size limits
- Step 1Check the bitrate so you know how big each minute is — File size in MB ≈
(bitrate in Mbps × seconds) ÷ 8. A 6 Mbps 1080p clip is ~45 MB per minute — so even a 30-second part can exceed Gmail's 25 MB. If your bitrate is high, compress to a target byte size with email-compressor before (or instead of) splitting. - Step 2Estimate the part count for your size cap —
parts ≈ ceil(total file MB ÷ target MB), then round up for headroom since parts aren't equal in bytes. A 120 MB clip for a 25 MB Gmail limit needs at leastceil(120 ÷ 25) = 5, but enter 6 so the heaviest part still fits. - Step 3Drop the video and set Number of parts — Accepts MP4, MOV, MKV, WEBM, AVI, M4V, TS. Enter your estimated part count (2–20). The split is by duration, not size — there is no 'under 25 MB' mode in this tool.
- Step 4Run and check the heaviest part — FFmpeg.wasm extracts each part with
-ss START -i input -t SEGLEN -c copy. After it finishes, look at the largest part's size — busy/high-motion sections produce the biggest files. If any part exceeds the limit, run again with one or two more parts. - Step 5Attach the parts in order — Extract
name-parts.zipand attachname-part-1first. Number them in the email so the recipient downloads and plays them in sequence; the parts play independently in any standard player. - Step 6If parts still won't fit, compress instead of splitting more — Past ~10 parts the recipient experience degrades. If a single minute already exceeds the cap, compress to a byte target with email-compressor (Gmail/Outlook presets) or whatsapp-compressor for chat, then split the smaller file only if needed.
Common email attachment limits
Provider caps as commonly documented. Corporate gateways frequently impose lower limits than the consumer service.
| Provider | Attachment cap | Over-limit behaviour |
|---|---|---|
| Gmail | 25 MB | Auto-converts larger files to a Google Drive link |
| Outlook.com / Microsoft 365 | ~20 MB | Blocks send; suggests OneDrive |
| Yahoo Mail | 25 MB | Blocks send over the cap |
| Apple iCloud Mail | 20 MB | Offers Mail Drop (iCloud link) instead |
| Corporate / Exchange | Often 10–20 MB | Gateway rejection, sometimes silent |
Picking a part count for a size cap
Splitting is by time, so size per part depends on bitrate. Always round the count up and check the heaviest part.
| Total file size | Cap 25 MB (Gmail) | Cap 20 MB (Outlook) |
|---|---|---|
| 60 MB | 3 parts (enter 3–4) | 3 parts (enter 4) |
| 120 MB | 5 parts (enter 6) | 6 parts (enter 7) |
| 200 MB | 8 parts (enter 9–10) | 10 parts (enter 11+) |
| 400 MB | 16 parts (or compress first) | 20 parts (compress first) |
Split vs compress for email
When the goal is a byte target, splitting alone may not be enough. Use the right tool for the cause.
| Situation | Best approach | Tool |
|---|---|---|
| File a bit over the cap, low motion | Split into 2–4 parts | This splitter |
| Single minute exceeds the cap | Compress to byte target, then split if needed | email-compressor |
| Need it under a chat limit (16 MB) | Compress for chat | whatsapp-compressor |
| Just want a clean first-half / second-half | Split into 2 parts | This splitter |
Cookbook
Recipes for getting a video into an email without a cloud link. Sizes are illustrative — always check the heaviest part.
120 MB clip under Gmail's 25 MB cap
Five 25 MB parts would be the ideal, but motion-heavy sections weigh more, so add headroom.
Input: demo.mp4 (120 MB, 12:00) Math: ceil(120 / 25) = 5 -> enter 6 for headroom Option: Number of parts = 6 Output: demo-parts.zip demo-part-1.mp4 ... -part-6.mp4 (~2:00 each) Check the busiest part is still < 25 MB before sending.
Outlook's tighter 20 MB limit
A lower cap means more parts. Round up and verify.
Input: screencast.mp4 (96 MB) Math: ceil(96 / 20) = 5 -> enter 6 Option: Number of parts = 6 Result: 6 parts averaging ~16 MB; heaviest ~19 MB -> fits.
When to compress first instead
High-bitrate phone footage can blow the cap in a single minute. Splitting more just makes many oversized fragments.
Input: iphone_4k.mov (60 MB for 0:30, ~16 Mbps) Split 20 parts -> ~3 MB each but 20 fragments, ugly UX. Better: email-compressor -> 24 MB single file -> attach once. (Route: /video-tools/email-compressor)
Two-part split for a slightly oversized file
If the file is only modestly over, two parts is the least-friction option.
Input: meeting.mp4 (38 MB)
Option: Number of parts = 2
Output: meeting-part-1.mp4 (~19 MB),
meeting-part-2.mp4 (~19 MB) -> both under Gmail 25 MBKeep a sensitive recording off cloud hosts
Splitting locally avoids the Drive/OneDrive link an over-limit attachment would otherwise force.
Input: hr_interview.mov (confidential, 88 MB) Option: Number of parts = 5 Processing is in-browser (FFmpeg.wasm) - no upload. Attach the 5 parts directly; nothing touches a server.
Edge cases and what actually happens
Equal time does not mean equal size
By designThe split is by duration, but file size tracks bitrate, so a high-motion segment can be twice the bytes of a static one of the same length. Always check the largest part against your email cap, not the average. Add a part or two for headroom when cutting close to the limit.
A single minute already exceeds the cap
Compress insteadIf bitrate is high (4K phone footage, screen captures at high fps), even short parts can blow past 25 MB. Splitting more just creates many oversized fragments. Compress to a byte target first with email-compressor, then split the smaller file only if still needed.
Part lands just over the limit
Boundary riskBecause boundaries snap to keyframes, a part can run slightly longer than duration ÷ parts and tip over the cap. Re-run with one more part to shorten each segment, or compress first to lower the per-second byte cost.
More than 20 parts needed
ClampedThe part count maxes at 20. A 600 MB file under a 20 MB cap mathematically needs ~30 parts — split into 20 first, then split the heaviest part again, or (better) compress before splitting so the count stays reasonable.
Recipient can't reassemble parts
ExpectedEach part plays independently, but they are separate files — the recipient watches them in order, not as one seamless video. If they need a single file, they can rejoin same-codec parts with video-merger. Number the attachments clearly in the email.
Container preserved, codec unchanged
PreservedSplitting copies streams, so a .mov stays .mov with the original codec. If the recipient's mail client or device can't play that codec, the issue is playback support, not the split — convert with video-transcoder before splitting if compatibility is a concern.
File over your tier's size limit
RejectedFree caps a single input at 1 GB. A multi-gigabyte master needs Pro (10 GB) or higher. The cap is on file bytes, not on how many parts you produce or how long the video runs.
Corporate gateway lower than the consumer cap
Verify locallyExchange and corporate filters often allow far less than Gmail's 25 MB and may strip attachments silently. Confirm your organisation's real limit and size the heaviest part below it; when unsure, compress first to a known small target.
Source duration can't be read
ErrorThe tool probes total duration before computing part length. A truncated or corrupt recording raises 'Could not determine video duration.' Repair or re-export the file, then split.
Frequently asked questions
Can I split a video to a specific MB size like 25 MB?
Not directly — this tool splits by part count, not by bytes, and equal time does not equal equal size because file size depends on bitrate. Estimate the count with ceil(total MB ÷ target MB), round up, then check the heaviest part. To hit an exact byte target, use email-compressor.
How do I send a long video by email without Google Drive?
Split it into parts each under the provider cap, then attach the parts directly. Gmail's limit is 25 MB and Outlook's about 20 MB. Because the split is lossless and runs in your browser, the video stays in the email and never touches a cloud host.
Why are my parts different sizes even though they're equal length?
Because file size follows bitrate, not duration. A high-motion or detail-rich segment encodes to more bytes than a static one of the same length. Always size the heaviest part against your cap and add headroom by choosing one or two extra parts.
What's Gmail's attachment limit?
25 MB. Files larger than that are automatically converted to a Google Drive link rather than attached. Splitting into sub-25 MB parts keeps the video as real attachments instead of a link.
What's Outlook's attachment limit?
About 20 MB for Outlook.com and Microsoft 365 consumer accounts; corporate Exchange gateways are often stricter. Size your parts below 20 MB (and verify the heaviest) for Outlook recipients.
How many parts should I use for email?
Start from ceil(total file MB ÷ cap MB) and round up for headroom, since parts vary in bytes. A 120 MB file for Gmail's 25 MB cap needs at least 5; entering 6 keeps the busiest part safely under the limit.
Is splitting lossless?
Yes. It uses FFmpeg stream-copy (-c copy), so each part is bit-identical to the source — no re-encode and no quality loss. The recipient sees exactly the original quality.
Will my confidential recording be uploaded?
No. The split runs entirely in your browser with FFmpeg.wasm, so the file never reaches a server. That's the main reason to split locally rather than relying on the over-limit Drive/OneDrive links email providers force on you.
Can the recipient rejoin the parts into one file?
Yes, if they want a single file. All parts share the same codec, so they can concatenate them losslessly with video-merger. Otherwise they simply play the parts in order.
What if I need more than 20 parts?
The count maxes at 20. If you'd need more than that, compress to a smaller file first with email-compressor so a reasonable count fits, or split into 20 then split the largest part again.
Which formats can I split for email?
MP4, MOV, MKV, WEBM, AVI, M4V, and TS. The output parts keep the same container as the input. If the recipient's device can't play that codec, transcode first with video-transcoder.
Should I split or compress?
Split when the file is modestly over the cap and you want zero quality loss. Compress when a single minute already exceeds the cap or you'd need a dozen-plus fragments — email-compressor hits a byte target so you can attach one clean file.
Privacy first
Every JAD Video tool runs entirely in your browser via WebCodecs and FFmpeg (WebAssembly). Your video files never leave your device — verified by zero outbound network requests during processing.