What to do when a video is too big to send

Why videos are so big

A video's size is almost exactly its bitrate (how much data is used for each second) multiplied by its length. Everything else feeds into the bitrate:

• Resolution — a 4K frame has four times the pixels of a 1080p frame and nine times those of 720p. More pixels need more data to look clean.
• Frame rate — 60 frames per second is twice as many pictures as 30, so phones recording at 60 fps make noticeably heavier files.
• Bitrate settings — phones and cameras record at a generous bitrate so the original keeps as much detail as possible for editing. That's far more than a clip needs to look good on a phone screen.
• Length — double the length and, at the same bitrate, you double the size. This is why a long video is the hardest to fit under a small limit.

Turn that around and you can see what a limit really means. 8 MB is 64 megabits: spread over a 60-second clip, that's about 1 megabit for every second — sound included. Over three minutes it's a third of that.

Know the limit you're aiming for

Limits differ between apps and change over time, so check the app's current limit before you start — it's usually in its help pages or the error message. Two common ones: our 8 MB preset is sized to fit under Discord's free upload limit and most chat apps', and Gmail accepts attachments up to 25 MB. For WhatsApp, other mail services and upload forms, check the number they give you.

Tip: Email attachments grow by roughly a third in transit because of how they're encoded, so a video that is only just under an email limit can still bounce. Aim comfortably below it.

Compress to a target size

1. Open Compress Video and add your video — MP4, MOV (including iPhone videos), WebM, MKV or TS, up to 10 at a time and 4 GB each.
2. Type the limit in Target size, in MB. Leave it at 0 to pick a quality level instead.
3. For phone or 4K footage, set Resolution to 1080p or 720p as well.
4. Click Compress and download the MP4. The result shows its new size.

From the video's length, the tool works out the bitrate that fits your target, keeps 5% headroom and sets aside room for the sound. Encoders don't hit a requested bitrate exactly, so if the first result is still too big it is re-encoded at a lower rate — and, if that stops helping, at a slightly smaller picture size. Quality never drops below a minimum, though, so a very long video can still end up over a small target. If a video is already so efficiently compressed that the result wouldn't be smaller, you're told so instead of being handed a bigger file.

For the two most common limits there are ready-made pages with the target already set: compress a video to 8 MB (which also drops to 720p) and compress a video to 25 MB.

How much quality a size leaves

This is the picture bitrate the target-size calculation leaves after headroom and sound. Higher is cleaner; for comparison, phones often record at many times these rates.

At a fixed size, a smaller resolution looks better, not worse: the same budget is shared by fewer pixels, so each frame comes out cleaner. That's why 720p is the right choice for anything aimed at a phone screen under a tight limit.

Cut what you don't need

Because length matters most, trimming is the most effective step of all. Most clips have a few seconds of setup at the start and fumbling at the end. Trim Video keeps only the part between a start and end time (in seconds). MP4, MOV and MKV come out as MP4; WebM stays WebM. Trim first, then compress the shorter clip — every second removed is bitrate the rest of the video gets to keep.

Lower the resolution or frame rate

If you only need the video to look good on phones, 1080p or 720p is plenty, and the Resolution option in Compress Video does this in the same step. A 60 fps clip can also go down to 30 fps with Change Frame Rate: the video lasts exactly as long, frames are dropped to reach the new rate, and the sound is untouched. Motion still looks normal at 30 fps for everyday clips.

Tip: Every re-encode costs a little quality. Do the steps that change the picture once, and leave compressing to a size target for last.

Split it into parts

When a video must stay long and sharp — a full talk, a lesson, a recording of an event — sending it in pieces can work better than squeezing it. Split Video cuts a video into 2 to 50 equal parts: a three-minute video in six parts gives 30-second pieces. The parts aren't squeezed to a size target, so each one's size is roughly the original's divided by the number of parts. You download them together as a ZIP.

Or send a link

For really long videos, uploading to a cloud storage service you already use and sending the link is often the better choice — the recipient gets the full-quality original. Keep in mind that many chat apps compress videos again when you send them as media, so a clip that looks crisp on your phone may arrive softer even when it fits the limit.