How to make a video smaller for WhatsApp, email or Discord

A minute of phone video is somewhere between 60 and 400 MB, and almost everywhere you might want to send it has a limit between 10 and 25 MB. This guide puts the limits in one table, explains why the files are so large, and shows the three ways to get under a limit, with the arithmetic so you can see what each one costs.

The limits, in one table

These are the published limits for the common free tiers, read from each platform’s own help pages on the date shown. They change, and they mean slightly different things (per file, per message, with or without a preview), so the notes matter as much as the numbers.

Two things stand out. First, the chat limits (WhatsApp 16 MB, Discord 10 MB) are far below the email limits, which are themselves far below what the file-sharing-style services allow. Second, the limit is almost never the whole story: WhatsApp will take a 2 GB video as a document, and Gmail will quietly turn a 100 MB attachment into a Drive link. Getting under the limit is about making the video play inline, where people actually watch it.

Why phone video is so big

A video’s size is its bitrate multiplied by its length. Phones record at high bitrates because they are optimising for quality in the moment, not for sending: an iPhone shooting 4K at 30 frames per second writes roughly 50 to 60 megabits every second, which is about 7 MB per second or 400 MB per minute. Even 1080p at 30 fps is typically 8 to 16 Mbps, or 60 to 120 MB per minute. Audio adds another 1 MB per minute at the usual 128 kbps.

Compare that with what a chat app needs. A 1080p clip looks perfectly good at 2 to 4 Mbps on a phone screen, and 720p looks fine at about 1 to 2 Mbps. So there is usually a factor of four to twenty between what the camera wrote and what the viewer can tell apart, and that gap is what compression recovers.

Three ways to get under a limit

1. Cut what you do not need. Trimming is the only method that loses nothing. If the moment you want to send is twenty seconds of a three-minute recording, a lossless trim removes 89% of the file before any compression is considered, in seconds, with the frames exactly as the camera wrote them. Use the trimmer first, always.

2. Lower the bitrate. Re-encoding at a lower bitrate is what people mean by compressing. The encoder keeps the resolution and frame rate and spends fewer bits per second, which costs fine detail first and sharp edges later. Down to about a third of the camera’s bitrate the difference is hard to see on a phone; below that it becomes visible in textures such as grass, water and hair.

3. Lower the resolution or frame rate. Halving the width and height quarters the pixels, which lets the encoder keep each remaining pixel looking good at a much lower bitrate. Going from 4K to 1080p for a video that will be watched on a phone is close to free in visible quality. Dropping 60 fps to 30 fps halves the frames and is noticeable only on fast motion.

A target-size compressor combines the last two automatically: it works out the bitrate that fits the size you asked for, and if that bitrate is too low for the original resolution to look acceptable, it steps the resolution down and says so. That is what the ClipHeron compressor does with its prediction line before anything is encoded.

Worked example: a 1.4 GB phone video to 16 MB

Take a 3 minute 12 second (192 s) 4K clip at 1.42 GB with 128 kbps audio, and a WhatsApp target of 16 MB.

Now trim first. Suppose the part worth sending is 40 seconds. The same 16 MB budget over 40 s gives 2.9 Mbps for video, which keeps 1080p comfortably and looks close to the original on a phone. Trimming turned a soft 720p result into a sharp 1080p one at the same file size. That is why the order matters: cut, then compress.

Platform by platform

WhatsApp. Use the 16 MB preset for a video that plays inline. WhatsApp applies its own compression on top, so very high quality is wasted anyway. For anything longer than a couple of minutes, consider sending it as a document instead; it will not preview, but the recipient gets the full file.

Discord. 10 MB without Nitro is tight. Short clips at 720p and 20 to 30 seconds fit; longer clips need trimming. If a server is boosted, the limit rises for everyone in it, which is worth checking before you compress hard. For a few silent seconds of reaction, a GIF under 8 MB is the native format and loops automatically.

Email. Gmail allows 25 MB and Outlook.com 20 MB per message, counting all attachments together, and both offer a cloud link automatically for larger files. For a video you want the recipient to download and keep, the link is often better than a compressed attachment.

iMessage. Apple does not publish a figure; around 100 MB is the practical limit, and Messages re-compresses videos aggressively unless you share the original from Photos as a file.

Slack and Telegram. Their limits (1 GB and 2 GB) are rarely the problem; the recipient’s connection and the preview behaviour are. Telegram shows an inline preview only up to a certain size, so a compressed 1080p version is friendlier than the camera original.

Keeping the quality

• Trim first. Every second you remove is a second of budget for the rest.
• Prefer dropping resolution to starving the bitrate. 720p at 1.5 Mbps looks better than 1080p at 0.6 Mbps.
• Check before you send. The before/after view in the compressor shows the same frame from both files at any point in the video.
• Keep the original. Compression is one-way. Send the compressed copy and keep the camera file.
• Mind the margin. Platforms count bytes their own way, so a file at 15.9 MB can read as 16.1 MB on the other side. The 4% margin in the budget exists for that reason.

Compress a video to a size limit Trim it first

This guide explains how things work in general terms. Platform limits and codec support change; the figures were checked on the date shown above. Spotted something out of date? Email errors@clipheron.com and we will check it against the source.