How small should a video be? Sizes that work

"Make the video smaller" hides two completely different dials: resolution and bitrate. Understand what each one does and you can hit the right file size on the first attempt.

The division of labour

Resolution decides whether it looks sharp. 1920×1080 looks crisp on a phone; 480×270 looks blurred. This is the difference the eye catches first.
Bitrate decides how much data per second describes the picture. Starve it and you get blocky artefacts and smearing, especially in fast-moving shots.

The conclusion that matters: drop the resolution to just enough, then give the bitrate room. That beats keeping a high resolution and squeezing the bitrate. 1080p at 3 Mbps looks perfectly clean. 1080p at 0.8 Mbps is a mosaic. The second file is smaller, but nobody wants to watch it.

Targets for three situations

Messaging apps — short side 720, bitrate 1.5–2.5 Mbps. About 12–18 MB per minute, perfectly watchable on a phone. Most messaging apps re-compress anyway, so pushing harder gains you nothing.
Email attachments — short side 480–720, bitrate 1–1.5 Mbps. About 8–11 MB per minute. Remember that MIME encoding inflates an attachment by roughly a third, so budget for it.
Web page background video — short side 480–720, bitrate 0.8–1.5 Mbps, and strip the audio track. Background video is almost always autoplayed muted; keeping audio is pure waste.
Archive for later editing — keep the original resolution, bitrate no lower than 6 Mbps. This is not really a compression job; just remux it.

Why phone video is so large

A phone recording 1080p at 30 fps typically runs 8–17 Mbps; 4K goes past 40 Mbps. Manufacturers set it that way so playback looks right on a large television and so you have headroom for editing. If the clip is going into a group chat or onto a web page, most of that bitrate is wasted.

The other lever people forget is frame rate. A 60 fps video is roughly twice the size of the same clip at 30 fps. If nothing in the shot moves quickly — a talking head, a product turning, a landscape — dropping to 30 fps costs you almost nothing and halves the file.

A real comparison

One minute of 1080p phone footage, 118 MB to start with:

Keep 1080p at 4 Mbps → about 30 MB, essentially indistinguishable to the eye.
Drop to 720p at 2 Mbps → about 15 MB, entirely fine on a phone.
Drop to 480p at 1 Mbps → about 7.5 MB, ideal for email, visibly soft full-screen on a monitor.

There is no universal answer to "how small", because it depends entirely on where it will be watched. Decide that first, then pick the numbers.

Doing it

The video compressor takes a resolution cap and a compression level and handles the rest. Encoding happens inside your browser, so the video is never uploaded — better for privacy, and you avoid the classic "upload failed at 80%" problem entirely. The trade-off is speed: browser encoding runs close to real time, so a 3-minute clip takes about 3 minutes. Keep the tab in the foreground.

If the result is still too large, cut the resolution before you cut the quality. That is the highest-value move available.