Resize image

Change dimensions in pixels or percent. Free, no upload. 1 GB max · Up to 1 GB · Processed locally, never sent to a server.

A photo out of a recent camera is routinely 4,000 pixels wide. Published as it stands in an article, it will be displayed at 800 pixels by the browser, but downloaded in full by every visitor. The opposite case is just as common: a registration form or a submission portal sometimes refuses anything above a given resolution. Either way, you have to build a smaller image, not merely display it smaller.

The tool takes one image at a time, in any format your browser can read, and immediately shows its real dimensions in the form "Original image: 4032 × 3024 px". You then give it a target, either in pixels or as a percentage of the starting size, and the pixel grid is recomputed on that new basis.

The reduction is not done in a single pass. As long as the target is more than twice as small as the source, the image is halved repeatedly, with smoothing set to its highest setting, before a final draw at the exact dimensions asked for. This descent by steps avoids the aliasing that an abrupt resize leaves on fine textures.

How to use it

  1. Drop one image One file at a time. As soon as it is read, the line above the options shows the original width and height in pixels, which saves looking them up elsewhere.
  2. Choose the mode In pixels to aim at a precise dimension, in percentage for a relative scaling. The selector reveals the matching fields and hides the others.
  3. Enter the target In pixels, fill in the width, the height, or both; an empty field is deduced. In percentage, the value runs from 1 to 500 and starts at 50.
  4. Keep the proportions or not The box that keeps the proportions is ticked by default. Unticked, it lets the image distort so as to occupy exactly the two values you entered.
  5. Click Run The progress line announces the resolution it has computed. The file obtained carries the original name followed by the new dimensions, for example photo-800x600.jpg.

Resampling is not the same as displaying smaller

Shrinking an image in a word processor, setting a width in CSS or zooming out in a viewer changes nothing in the file: every pixel is still there, simply drawn on a smaller surface. The weight stays the same, and so does the download time.

Here the pixel grid is rebuilt. A 4,000 × 3,000 photo brought down to 800 × 600 goes from twelve million pixels to four hundred and eighty thousand: the others are not hidden, they are merged by successive averaging. That is what makes the file size drop, and it is also what makes the operation irreversible.

Aspect ratio, and what the checkbox actually does

The aspect ratio is the width divided by the height: preserving it guarantees that a face is not stretched and that a circle stays round. With the box ticked and a single field filled, the other dimension is computed from that ratio then rounded to the nearest whole number, which is where results such as 800 × 533 come from.

With the box ticked and both fields filled, the tool keeps the smaller of the two scale factors: the image fits entirely inside the rectangle described, without necessarily filling it. Asking for 800 × 800 on a panoramic photo therefore gives something like 800 × 450, and not a square. For square framing you have to cut, which is what the Crop an image tool does.

With the box unticked, both values are applied literally and the image is stretched. A field left empty then takes back the original dimension, which distorts along one axis only.

Enlarging restores no detail

The percentage goes up to 500, and nothing stops you entering a width larger than that of the source. It is worth knowing what this produces: the added pixels are interpolated, that is, computed as averages of their neighbours. No new information appears, because there is none left in the file.

What you see is a progressive blur and, on an image already compressed as JPG, an enlargement of the artefacts already present. Enlarging only makes sense to reach the minimum resolution demanded by a service, never to recover an unreadable detail. In that last case, the only answer is to find the original file again.

Output format and what is not carried over

The output format follows a simple rule: a PNG going in comes back as a PNG, with its transparency intact; everything else comes back as JPG at a fixed quality level of 92 %. A WebP you drop therefore returns as JPG, and an animated GIF returns as a still image, the one from its first frame.

Because the image is redrawn in a canvas, the EXIF metadata of the original photo, date, camera model and GPS coordinates included, is not written back into the file produced. The computation is handled by your own device, which is why a very large photo ties the tab up for a moment.

Frequently asked questions

Why do I get 799 px when I asked for 800?

Because the deduced dimension is rounded to a whole number. If you filled both fields with the proportions kept, it is the smaller of the two scale factors that applies, so that the whole image fits inside the frame.

Can I resize several photos at once?

No, this tool works on one file at a time, because it reads the dimensions of the loaded image in order to show them to you before the computation. For a batch, the operation has to be repeated.

My WebP came back as a JPG, is that normal?

Yes. Only PNG keeps its format, precisely in order to preserve transparency. The other readable formats are re-encoded as JPG at 92 %.

The message asking for at least a width or a height appears.

In pixel mode, at least one of the two fields has to hold a number: with both empty, the tool has no target to compute. In percentage mode, the value has to be strictly greater than zero.

Does enlarging an image to 200 % make it sharper?

No. Interpolation creates intermediate pixels from those that already exist; the image becomes larger and blurrier, never more detailed.

What happens to an animated GIF?

Only its first frame is read and resized. The result is a still JPG, the animation not being kept.

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