The fastest way to shrink an MP4 is to re-encode it at a lower bitrate

An MP4 file shrinks when you compress the video data inside it — usually by lowering the bitrate, which controls how much information the video stores per second. A typical 1080p video at 5000 kbps (kilobits per second) takes up far more space than the same video at 2000 kbps. The trade-off is visible: lower bitrate means softer details and more compression artifacts, but for many uses — social media, email, or playback on phones — the difference is acceptable.

The most practical tool for this is HandBrake, which is free and runs on Windows, Mac, and Linux. You load your MP4, choose a target bitrate or file size, and let it re-encode. The process takes time (usually 30 minutes to several hours depending on length and your computer's speed), but you end up with a genuinely smaller file that plays on any device that plays MP4s.

If you need the file smaller but do not want to wait for re-encoding, you can also trim unused footage, remove audio tracks you do not need, or change the resolution — but these are smaller wins than bitrate reduction.

Key Takeaways

  • Lowering the bitrate shrinks the file most effectively, but takes 30 minutes to several hours depending on video length and your computer speed.
  • HandBrake is free software that handles bitrate reduction and works on Windows, Mac, and Linux without requiring technical knowledge.
  • Removing audio tracks, trimming footage, or lowering resolution also reduces file size, but bitrate change has the biggest impact.
  • A 1080p video at 2000 kbps is noticeably smaller than the same video at 5000 kbps, with visible quality loss that may or may not matter for your use.

Using HandBrake to re-encode at a lower bitrate

read HandBrake from handbrake.fr and install it. Open the program, click the folder icon in the top left, and select your MP4 file. HandBrake will load it and show you the current video properties — resolution, frame rate, and bitrate.

On the right side under "Video", you will see a bitrate field. If your original file is 5000 kbps, try 2500 or 3000 kbps as a starting point. Lower numbers mean smaller files but more visible quality loss. For video you are uploading to social media or sending via email, 2000–2500 kbps usually looks acceptable. For archival or playback on a large screen, stay closer to 4000 kbps.

Click "Start Encode" at the top right. HandBrake will process the video and save the new MP4 to your chosen folder. The original file stays untouched. When encoding finishes, compare the file sizes — you should see a reduction of 30 to 70 percent depending on how much you lowered the bitrate.

Trimming and removing audio tracks for smaller files

If you do not need the entire video, trimming unused sections saves space without re-encoding. In HandBrake, click the "Chapters" tab and use the start and end time fields to select only the portion you want to keep. This is much faster than re-encoding because HandBrake copies the video data as-is instead of recalculating it.

You can also remove audio tracks you do not need. If your MP4 has multiple language tracks or commentary you do not use, click the "Audio" tab and delete the extra tracks before encoding. A stereo audio track takes up roughly 128–192 kbps, so removing one saves noticeable space if your file has several.

These changes alone will not shrink the file as much as lowering bitrate, but they are useful if you want to keep the original video quality and only remove content you do not need.

Changing resolution to reduce file size

Lowering the resolution — from 1080p to 720p, for example — also shrinks the file. In HandBrake, click the "Dimensions" tab and change the width and height. A 1080p video (1920 × 1080) re-encoded at 720p (1280 × 720) will be noticeably smaller, especially if you also lower the bitrate.

Resolution change is useful if you are creating video for phones or small screens, where the difference between 1080p and 720p is barely visible. For anything larger — a monitor or TV — the quality loss becomes obvious. Combine resolution reduction with bitrate reduction only if you need the file very small and do not mind the visible quality drop.

Understanding bitrate and how it affects file size

Bitrate is the amount of data the video uses per second, measured in kilobits per second (kbps). A 10-minute video at 5000 kbps uses roughly 3.75 gigabytes of data (5000 kbps × 600 seconds ÷ 8000 to convert to megabytes). The same video at 2000 kbps uses only 1.5 gigabytes. The math is straightforward: lower bitrate equals smaller file.

The catch is that bitrate controls quality. High bitrate preserves fine details — skin texture, text on screen, fast motion. Low bitrate saves space by discarding detail the compression algorithm decides is less important. At 2000 kbps, you might see "blocking" (square artifacts) during fast scenes or soft edges on text. At 5000 kbps, these problems largely disappear.

The right bitrate depends on what you are doing with the video. Social media platforms compress video anyway, so uploading at 3000 kbps is usually enough. Archival or professional use might demand 6000–8000 kbps. Personal playback on a phone works fine at 2000 kbps.

Other tools if HandBrake does not fit your workflow

FFmpeg is a command-line tool that does the same job as HandBrake but requires typing commands instead of clicking buttons. If you are comfortable with a terminal, FFmpeg is faster and more flexible. The command to lower bitrate is straightforward: ffmpeg -i input.mp4 -b:v 2500k output.mp4 sets the bitrate to 2500 kbps.

Online converters like CloudConvert or Convertio let you upload an MP4 and read a smaller version without installing software. These are slower (upload and read times add to processing time) and less private (your video goes to someone else's server), but they work if you do not want to install anything.

Video editing software like DaVinci Resolve (free version available) or Adobe Premiere can also export MP4s at custom bitrates, but these are overkill if you only need to shrink a file without editing it.

Frequently Asked Questions

How much smaller will my file be if I lower the bitrate?

File size scales roughly with bitrate. If you cut the bitrate in half, the file will be about half the size. A 1 GB file at 5000 kbps becomes roughly 500 MB at 2500 kbps. The exact reduction depends on the original bitrate and the target bitrate you choose.

Will lowering bitrate make the video unwatchable?

Not at reasonable bitrates. A 2000–3000 kbps video looks acceptable on phones and tablets. You will notice quality loss on a large monitor or TV, especially during fast motion or scenes with fine detail. Test a short clip at your target bitrate before encoding the whole file.

Can I shrink an MP4 without re-encoding?

Trimming and removing audio tracks shrink the file without re-encoding, but the savings are small compared to bitrate reduction. Re-encoding takes longer but produces much smaller files. If speed matters more than file size, trimming is the faster option.

Does HandBrake work on Mac and Linux?

Yes. HandBrake runs on Windows, Mac, and Linux. read the version for your operating system from handbrake.fr. The interface and process are identical across all three.

What bitrate should I use for uploading to YouTube or TikTok?

YouTube recommends 5000–12000 kbps for 1080p uploads, but the platform re-encodes everything anyway. You can upload at 3000–4000 kbps and YouTube will handle the rest. TikTok compresses heavily, so 2000–3000 kbps is sufficient. Check the platform's upload guidelines for your specific resolution.