Why does the cut start slightly before my start time?

Copy mode cuts at keyframes, which sit every 1–10 seconds in most files. Choose “Re-encode” for a frame-accurate cut at the cost of a re-encode.

Can I trim a MOV or WebM?

Yes — the clip is delivered as MP4 (H.264/AAC), which plays everywhere. For WebM output use the Video converter after trimming.

Is there a length or size limit?

Files up to several gigabytes work on a desktop browser; phones are limited by memory to roughly 1–2 GB.

Is my video uploaded?

No. Trimming runs entirely in your browser.

Video Converters

Video Trimmer

Keep only the part that matters — the 20 seconds of a 10-minute recording, or a clip from a screen capture — and get a clean MP4 without re-uploading anything anywhere.

Runs in your browser when it can; large or unusual files use our EU server and are deleted within 1 hour.

Drop MP4, MOV, WebM, MKV file here

or click to browse · paste from clipboard · up to 4000 MB

Select file

Options

Start (seconds)

End (seconds)

Everything outside start–end is removed

Video

Quality

Audio

Why convert MP4 to MP4

Trimming sets a start and end time and copies just that range into a new MP4. When the video is already H.264, the stream is cut at the nearest keyframe and copied without re-encoding, so quality is untouched and a 1 GB file trims in seconds.

Everything happens on your device through the browser’s media APIs. No watermark, no length limit beyond your device’s memory, and HEVC iPhone clips work in Safari, Edge and Chrome with hardware decoding.

How to convert files to MP4

Drop the video onto the page.
Type the start and end time in seconds (e.g. 12.5 to 47).
Click Trim and download the MP4 clip.

About the formats

MP4 · MPEG-4 Part 14 video · .mp4

The video format that works everywhere: phones, TVs, browsers, social networks. Normally H.264 video with AAC audio.

MP4 is a container; the codec inside (H.264, HEVC/H.265, AV1) decides what can play it.
H.264 MP4 is the safe choice for uploads and sharing; HEVC MP4 from newer iPhones needs extra codecs on Windows.
The “moov atom” placement decides whether a browser can start playing before the whole file downloads.

MOV · QuickTime movie · .mov

Apple’s QuickTime container, the default for iPhone videos and Mac screen recordings; very close to MP4 but not accepted everywhere.

MOV and MP4 share the same underlying structure, so MOV to MP4 usually only needs repackaging, not re-encoding.
iPhone MOV files are often HEVC (H.265) with HDR, which Windows and many web apps cannot play without conversion.
Screen recordings on Mac are MOV with H.264 and can be very large.

WebM · WebM video · .webm

The royalty-free web video format (VP8/VP9/AV1 video, Vorbis/Opus audio) produced by browser screen recorders, Discord and many online tools.

WebM is based on Matroska and plays in every browser, but not in iMovie, Premiere or on most phones without conversion.
Browser recording APIs output WebM, which is why screen recordings from web apps come as .webm.
WebM to MP4 requires re-encoding the video, because MP4 does not carry VP9 widely.

MKV · Matroska video · .mkv

An open container that can hold any codec plus multiple audio tracks, subtitles and chapters; popular for rips and downloads, unsupported by iPhone and many TVs.

MKV to MP4 keeps the video quality when the codec is H.264 or HEVC — only the container changes.
MP4 cannot carry every MKV feature: soft subtitles and some audio codecs (e.g. DTS) must be converted or dropped.
Most desktop players (VLC, MPV) play MKV; Safari, iOS and PowerPoint do not.

Related conversions

Compress VideoPopularMake a video small enough for email, WhatsApp or uploads.MP4 to GIFPopularOn-deviceVideo clip to an animated GIF with trim and size controls.MP4 to MP3PopularPull the audio out of a video as an MP3.MOV to MP4PopulariPhone/Mac MOV to MP4, usually without re-encoding.MKV to MP4PopularMKV to MP4 by remuxing, lossless and fast.WebM to MP4PopularBrowser screen recordings (WebM) to MP4.

More in Video Converters · All converters