Resize Video

The three modes are not interchangeable

This is the part that decides whether you get what you wanted, and no other resizing tool explains it.

Preset resolution — 4K, 1080p, 720p, 480p, 360p — fits your video inside that exact frame and fills the leftover space with black bars. Nothing is cropped and nothing is squashed, but if your video's shape does not match the preset's shape, you get bars. Feed a vertical phone clip into 1080p and you get a wide frame with your video in a narrow strip down the middle.

That is the correct behaviour when you need to hit an exact frame size — a platform that demands 1920×1080, a slot in an edit where every clip must match. It is the wrong behaviour if you just wanted a smaller file.

Scale by percentage — 25%, 50%, 75% or your own number — keeps your video's shape exactly as it is. No bars, no cropping, no distortion. This is what most people actually want, and it is worth saying clearly because it is not the mode the tool opens on. If your goal is "make this file smaller" or "this 4K video is overkill", this is your mode.

Custom dimensions gives you a width and height box and applies them literally. If your numbers match your video's proportions, you get a clean resize. If they do not, the picture stretches — faces get wider or taller. Powerful when you know exactly what you need, and a trap otherwise. Work out the matching number before you type it: for a 1920×1080 source, a width of 1280 needs a height of 720.

Check your starting resolution first

As soon as you choose a file, the tool reads and displays its actual resolution. Use that number — it answers the question that makes the rest of the decision easy.

Phone video in particular is rarely what people assume. A recent phone may be shooting 4K without you having chosen it, which is why the file is enormous. Many clips are vertical at 1080×1920, which is the opposite shape to the 1920×1080 preset labelled "1080p" — a distinction that trips people up constantly.

And there is no point resizing upward. Percentage mode will go to 400%, and it will faithfully produce a video four times the size with no more detail in it than the original had — just larger, softer pixels and a much bigger file. The detail was never captured; enlarging cannot invent it.

Smaller frame, smaller file — and why that is the real reason people are here

Resolution is usually the biggest single factor in a video's file size, and halving the dimensions removes three-quarters of the pixels. Going from 4K to 1080p is a dramatic reduction, and for anything watched on a phone or embedded in a web page the difference is genuinely invisible.

A practical rule: 1080p is enough for almost everything. Social feeds, web embeds, presentations, email — 1080p looks sharp on every screen most viewers own. 720p is fine for screen recordings and talking-head video, where fine detail does not matter. Keep 4K only when the footage will be edited, cropped into, or shown on a large display.

If size is your actual goal rather than dimensions, note that reducing the bitrate is the other lever, and a dedicated compressor gives you more control over the trade-off than resizing does.

What happens to the file

The audio is copied across untouched — the same stream, bit for bit, since changing the picture size has nothing to do with the sound.

The video itself is re-encoded, which is unavoidable: every frame is being redrawn at a new size. One pass costs very little visible quality. What does cost you is running the same clip through several tools in a row, so if you are also trimming or cropping, do the resize last.

Dimensions are rounded down to even numbers, because the H.264 encoder requires it. So 50% of a 1921-pixel width becomes 960 rather than 960.5 — a difference nobody will ever see, but it explains the occasional one-pixel discrepancy.

The output is always an MP4, which is the right default for anything going online.

And the whole thing happens on your own machine. No upload, no watermark, no account, no file size limit — and no waiting for a queue on somebody else's server, which for video is usually the slowest part of using a free online tool.

Related tools

Video Compressor is the better choice when file size rather than dimensions is the goal. Crop Video changes the shape by cutting rather than padding — use it instead of a preset if you want to fill a frame without bars. Video Converter changes the format.