Trim, crop, rotate and resize video

Three of these six changes are free

Editing video is usually assumed to mean re-encoding it: every frame decoded, changed, and compressed again, with time and quality spent in the process. For half of what this page does, that assumption is simply wrong. Rotating a video, removing its soundtrack, and cutting off the end can all be done without decoding a single frame — the compressed picture is copied from one file into the next exactly as it is. The result comes out in seconds no matter how long the video is, and it is not merely close to the original, it is bit-for-bit the same picture.

The reason is worth knowing, because it explains where the boundary falls. A rotation isn't stored by turning pixels; it's a number in the file's header that tells the player which way up to render. Removing audio means writing one fewer track. Cutting the end means stopping the copy early. None of those requires understanding the picture, so none of them touches it. Cropping, scaling and changing the frame rate are the opposite: each one produces frames that didn't exist in the source, which can only come from decoding and re-compressing everything.

This tool works out which side of that line your selection falls on, per change, and shows it before you commit. Pick only free changes and you get the instant path. Add one that isn't, and the whole video is re-encoded — there's no partial version of that, which is why the badge switches the moment you touch one of them.

When re-encoding does happen, the video comes out as H.264 with AAC audio, the pairing that plays everywhere. That's a deliberate choice about portability, and it has one consequence worth reading below if your source is HEVC.

Trimming: why the end is free and the start isn't

The timeline has two handles and they do not cost the same thing. Dragging the right one shortens the video by stopping the copy early — nothing is decoded, nothing is compressed, and a two-hour file is trimmed about as fast as a two-minute one. Dragging the left one re-encodes the entire remaining video, and it's worth understanding why rather than treating it as an arbitrary limitation.

Compressed video is not a series of independent pictures. A keyframe is complete on its own; the frames after it store only what changed since, sometimes for several seconds at a stretch. Cut at an arbitrary point and you land in the middle of one of those runs, holding frames that describe changes to a picture you no longer have. There are only two honest ways out: quietly extend your cut backwards to the previous keyframe — handing back up to several seconds you explicitly asked to remove — or decode from that keyframe and re-encode from your actual cut point. This tool takes the second, so the video starts where you said it starts.

In practice that means cutting a long intro off a long video takes real time, and cutting the tail off the same video doesn't. If you only need one of the two, doing just the end is dramatically cheaper. If you need both, the cost is the same as doing the start alone — a single pass handles everything you've selected.

The soundtrack follows the same rule. Trimming the end copies the audio untouched; trimming the start re-encodes it to AAC. One case has no good outcome: a Dolby track can't be re-encoded in a browser at all, so trimming the start of a file with Dolby audio means losing the sound. The panel says so before you start, and moving the start handle back to zero keeps the track.

Cropping and rotating, and the order they happen in

Drag a box on the preview to crop. Drag inside the box to move it, drag a corner to resize it, tap once to clear it. It also works from the keyboard: focus the box and the arrow keys nudge it, holding Shift resizes it instead — useful when you want a precise edge and a trackpad isn't cooperating.

Rotation is applied first, and the crop box lives in the rotated picture. This matters as soon as you use both: rotate a landscape video to portrait and the frame becomes 1080 wide by 1920 tall, so a box that was near the right edge is now near the top. Rather than making you re-draw it, the box turns with the picture and keeps hold of whatever you framed. Resolution is applied last, to whatever the crop left behind — so cropping a 1080p video to a small region and then choosing 720p gives you 720p of that region, not a 720p frame with a small region in it.

One thing the crop box cannot do is preview a file your browser can't play. MKV and ProRes are the common cases: this tool reads them perfectly well, but the browser's own video element often won't display them. When that happens you get a correctly-proportioned empty frame instead of a picture, and the crop still works — you're drawing on the right shape, just without the reference. Cropping is disabled entirely for codecs that can't be decoded at all, since a crop that can't be rendered isn't a crop.

1. Rotate first if you're going to. The crop box follows the picture, so you won't lose your framing.
2. Drag out the region you want to keep. The area outside it dims so you can see the result.
3. Choose a resolution if you also want the output smaller. It applies to the cropped region.

Both output dimensions are rounded to even numbers, because video encoders require it. A crop of 801 pixels becomes 802 — a difference you will not see, and the only alternative would be refusing the crop.

Resolution, frame rate, and what actually makes a file smaller

Resolution and frame rate can only go down here. Choosing a resolution higher than the source would invent detail that was never recorded and charge you bytes for it; the same goes for frame rate, where the extra frames would be duplicates. Options above your source are hidden rather than offered and quietly ignored.

Lowering the resolution does reliably shrink the file, because fewer pixels genuinely need fewer bits. Lowering the frame rate is a different story, and this is where a lot of advice is wrong. Fewer frames per second does mean less data in principle — but the encoder here picks its bitrate from the output's dimensions, not from how many frames it's given, so halving the frame rate does not halve the file. What it reliably does is make motion choppier. Change frame rate when 60fps is more than you need for the destination, not as a way to save space.

If size is the goal, this is the wrong page and the compressor is the right one: it lets you set a quality level or a target size and works backwards to a bitrate. What this page does to size is mostly incidental — trimming makes the file shorter and therefore smaller, cropping and scaling reduce it, and rotating or muting barely move it.

There's one way this page can make a file bigger. If your source is HEVC — which is what recent iPhones record — and you make a change that re-encodes, the result is H.264, because that's what plays everywhere. H.264 needs more bits than HEVC for the same picture, so a cropped HEVC clip can come out larger than the original despite having fewer pixels. Rotating, muting and end-trimming avoid this entirely: they keep the HEVC exactly as it was.

What happens to the soundtrack

Removing the sound is the simplest operation on this page: the audio track isn't written, the video track is copied, and the file comes out in seconds. It's a genuine removal rather than a volume change — the track is gone, not silent, so nothing can recover it and the file is slightly smaller.

When you keep the sound, what happens to it depends on the other changes. Everything except trimming the start copies the audio bit-for-bit, surround channels and all. Trimming the start re-encodes it to AAC for the same keyframe reason the picture has, which is quick and doesn't affect the video. Multichannel audio is mixed down to stereo on that path, because browser AAC encoders refuse multichannel input outright — a downmix beats a failed export.

Dolby Digital is the exception, and the panel spells it out when it applies. AC-3 and E-AC-3 tracks can be copied but not re-encoded, since browsers ship no Dolby decoder. So they survive every change on this page except one: trimming the start, which forces a re-encode that cannot happen. Rather than failing the whole export, the tool drops the audio and tells you first — and trimming only the end keeps the track intact.

What this tool doesn't do

This is a single-pass adjustment tool, not an editor, and the edges are worth stating plainly rather than leaving you to discover them.

1. It outputs MP4 only. Whatever you put in, what comes out is an MP4.
2. One clip, one pass. There's no joining two videos, no cutting a section out of the middle, and no batch queue.
3. There's no timeline scrubbing or playback preview of the result. The preview shows the frame at your start point so you can see what you're cropping — it isn't a player.
4. No filters, no colour adjustment, no speed change, no text or watermarks.
5. Subtitles, chapters and attachments are dropped, as they are anywhere this site converts video. Only picture and sound are carried over.
6. There's no size limit, but there is a disk check. The result is written to local storage as it's produced, so memory doesn't grow with the file — but the space has to exist, and that's verified before anything starts.

Your original is never modified or moved. What you download is a new file, so deleting the source stays an explicit decision you make yourself.

FAQ