Shotcut has no email preset, and the official pages we could find give no formula for estimating the size of an export. What they do document is a quality percentage, a project resolution you can lower, and a hardware-encoding switch that changes the size-versus-speed trade. So compressing for email in Shotcut is a short loop: set those knobs, export, check the file size on disk, adjust.
Everything below comes from Shotcut's own User Guide, FAQ, and release notes — where those pages stop short, this article stops with them.
Before you start
- Know the cap you are aiming at. Mail providers differ from each other and change their own numbers, so check your provider's current limit first. If you are sending through Gmail, start with Gmail's attachment size limit.
- Expect a re-encode. The User Guide is blunt about this: "Shotcut can not "pass through" or copy codecs without re-encoding." Making a file smaller is an export, not a re-wrap.
- Know where the panel is. Per the guide: "The Export panel (also File > Export Video...) is used to create a new video or audio file from your project because File > Save saves a project file."
Step 1: Export less video, not just smaller video
The From dropdown at the top of the Export panel decides what gets encoded, and the guide lists several sources. "Timeline: This is the default if you have added anything to the Timeline." "Source: You can export a single clip that has been trimmed and filtered in the Source player." And "Marker...: Exports a range Marker, which is a marker with a duration."
The marker route has a rule worth knowing: "Export > From lists all range markers (duration longer than 1 frame). Selecting a marker here allows the exporting of just that section of the timeline." A single-frame marker will not appear there.
If the recipient only needs 40 seconds of a four-minute cut, this is the first knob to reach for — it costs nothing in picture quality.
Step 2: Start from the default, not from a guess
You do not have to pick a preset at all. The guide says so directly: "NOTE: It is not necessary to choose a preset! Shotcut comes with default values that creates a high quality H.264 MP4 file at a reasonable size and speed that automatically adapts to the resolution, frame rate, and visual complexity of your project."
One wrinkle if you go looking for the Default preset's specification: the official pages describe it in two different ways. The User Guide calls it "high quality H.264 MP4", while the FAQ's preset suggestions list it as "Default (moderate quality H.264)". Neither page attaches a CRF or bitrate number to it.
The FAQ's suggestions cover uploading to a video-sharing site ("H.264 High Profile or YouTube"), putting video on your own site ("WebM and/or Default (moderate quality H.264)"), extracting audio, and intermediate files for other tools. Email is not one of the cases that list addresses, so treat Default or H.264 as your starting point and tune from there.
Step 3: Lower the quality percentage
Shotcut expresses encoding quality as a percentage rather than a CRF value. The one percentage figure named in the official release notes is a preset default: "Export preset H.264 High Profile now defaults to a higher quality 65% than YouTube or the defaults." (Release 25.01.25.)
The User Guide's example preset scenarios do suggest a mid-range quality percentage for draft exports and a somewhat higher one for web delivery — see the guide for the exact numbers. What you will not find anywhere official is a conversion between Shotcut's percentage and a CRF value, so ignore the "55% equals CRF 23" style tables that circulate elsewhere.
If you go hunting for these controls behind the Advanced button, read the warning the guide attaches to it: "However, by clicking Advanced you should understand that Shotcut expects you to be advanced and know what you are doing. There are simply too many combinations of settings and options that Shotcut's advanced export mode lets you create invalid combinations and does not protect you from yourself."
Step 4: Drop the resolution
When quality percentage alone is not getting you there, resolution is the other lever the documentation names. In its list of ways to reduce memory usage during export, the guide says simply: "Reduce the resolution of the Video Mode."
Note where the export resolution comes from. The guide's advice in the preview-scaling section is: "You should leave the export resolution set to the project resolution unless your preset or video codec dictates a resolution." In other words, change the project's Video Mode rather than fighting the export panel.
Step 5: Turn hardware encoding off when size is the goal
This is the step people get backwards. Hardware encoding is a speed feature, and the guide is explicit that it can cost you file size: "File sizes may be larger at the same quality target." An "Important nuance" box in the same section adds: "Hardware encoding is usually less compression-efficient, not lower quality."
So an export that got bigger after you ticked the hardware encoder is documented behaviour, not a bug. The guide's own recommendation splits along exactly this line — enable hardware encoding for "Long exports High-resolution video Preview or draft renders Laptop or low-power systems", and "Prefer software encoding for: Maximum compression efficiency Archival-quality exports Advanced codec tuning". An email attachment is a maximum-compression-efficiency job.
For which codecs the hardware path actually covers, see Shotcut hardware encoding and supported codecs — the official sources disagree with each other there.
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
The tool above does the same job in a browser tab, with a target size instead of a percentage, and without the export queue. Your file is read and re-encoded locally rather than uploaded, so a private clip stays on your machine. The general-purpose video compressor is the same engine with the target left up to you.
Step 6: Export, then measure
Click Export File, name the file, and leave the application alone — the Quick Start guide's instruction is "Do not close Shotcut until the export finishes."
Then check the size on disk. With no published size formula to work from, measuring is the method: the first export tells you how your project responds to a percentage change, and the second one usually lands.
Common mistakes
- Expecting a container change to shrink the file. Properties > Extract Sub-clip "will find the key frame closest to the in/out points and copy the codecs into a new container without re-encoding" — it is described as the closest thing to pass-through, not as a compression feature, and the guide warns it rounds to the nearest keyframe and drops any filters you applied.
- Leaving the hardware encoder on. See Step 5 — for the same quality target the guide says files may come out larger.
- Treating a preset as a safe configuration. The guide lists what presets are not: "Project templates Guaranteed-safe configurations Automatically compatible with all codecs or hardware encoders". It also notes that "Some export presets may not support hardware encoders".
- Improvising codec and container combinations in Advanced. The guide's list of pitfalls includes "Choosing a codec not supported by the selected container" and "Enabling hardware encoding with unsupported formats", and says these can "Cause export failure Produce unplayable files Result in silent audio or missing video".
- Forgetting audio. Release 25.07.26 records that Shotcut "Changed the default Export > Audio > Rate control to Average Bitrate for AAC, Opus, and MP3." On a long, quiet talking-head clip the audio track is not a rounding error.
FAQ
Does Shotcut have a preset for email attachments? Not in the FAQ's list of preset suggestions, which covers video-sharing sites, your own website, audio extraction, intermediate files, Linux screen recording, and SDI/HDMI capture. Start from Default or H.264 and lower the quality percentage and resolution yourself.
What quality percentage gets me under 25MB? No official Shotcut page we could find publishes a size-estimation formula, so there is no honest single answer. Export once at a lower percentage, check the file on disk, and adjust from that measurement.
Does enabling hardware encoding make the file smaller? The guide says the opposite is likely: "File sizes may be larger at the same quality target", because "Hardware encoding is usually less compression-efficient, not lower quality." Use it for speed, not for size.
Can I compress in Shotcut without re-encoding? No — "Shotcut can not "pass through" or copy codecs without re-encoding." The FAQ says Extract Sub-clip "is not frame accurate and there are some pitfalls" and points to LosslessCut, VirtualDub, or Avidemux for that job, while noting those usually have the same limitations.
My export has no sound or will not play. Did compressing break it? Possibly, if you changed settings in Advanced. The guide attributes silent audio, missing video, unplayable files, and outright export failure to invalid codec, container, and pixel-format combinations.
Compressing for email in Shotcut is two knobs and a measurement, not a magic number — and if you would rather skip the export queue entirely, the browser tools above handle the same file. Browse the rest of them at all Clapr tools, or read more walkthroughs in the how-to guides.
Quotes above are from Shotcut's official User Guide, FAQ, and release notes, checked against a September 2026 snapshot. Release-note lines describe what changed in that version, not necessarily the current state.
