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Image Resizer

Image Tools · Added

Resize an image to exact dimensions or a percentage of the original, keeping the aspect ratio unless you unlock it. Files are read straight from your device and re-drawn by your own browser — nothing is uploaded, and the tool works the same whether the image is a screenshot or a scanned document.

Or drop files onto this box.

JPG, PNG, WebP, GIF, BMP or AVIF. Up to 20 files, 30.00 MB each. They are read from your device and never uploaded.

Resize by

Pixels. Leave blank to derive it from the height.

Pixels. Leave blank to derive it from the width.

With both width and height set, the image is fitted inside that box rather than stretched to it, so one side may come out smaller than asked.

Output format

PNG is lossless, so quality does not apply to it.

How to use the image resizer

  1. 1Choose one or more images, or drop them onto the box.
  2. 2Pick how to resize: an exact size in pixels, or a percentage of whatever each image already is.
  3. 3For an exact size, fill in the width, the height, or both. Leaving one blank derives it from the other.
  4. 4Leave "Keep the aspect ratio" ticked unless you deliberately want to stretch the image. With it ticked and both sides set, the image is fitted inside that box rather than distorted to fill it.
  5. 5Check the preview and the reported output dimensions, then download each image.

Examples

A phone photo scaled for a blog post

Input
4000×3000 JPEG · width 1600 · height blank · ratio locked
Result
1600×1200

Setting one side and leaving the other blank is the usual case. The height follows from the original proportions, so nothing is distorted.

Fitting inside a fixed box

Input
4000×3000 JPEG · width 800 · height 800 · ratio locked
Result
800×600, not 800×800

Both sides were given, so the image is contained within the box. The width binds first on a landscape photo, which is why the height comes out at 600.

Deliberately stretching to a fixed shape

Input
4000×3000 JPEG · width 800 · height 800 · ratio unlocked
Result
800×800, visibly squashed

Unlocking the ratio does exactly what it says. It is occasionally what you want for a texture or a background, and almost never what you want for a photograph of a person.

Halving a batch of screenshots

Input
12 PNG screenshots · percentage mode · 50%
Result
Each image at half its own width and height

Percentage mode scales every image relative to its own size, so a mixed batch keeps its relative proportions instead of being forced to one shared size.

About the image resizer

Dimensions, aspect ratio and the box that contains them

Almost every resizing mistake comes from the same confusion: whether the numbers you typed are a target shape or a bounding box. If you ask for 800×600 and your photograph is 4000×3000, both readings give the same answer, because the proportions already match. If the photograph is 4000×2000, they diverge sharply — the target-shape reading squashes it to 800×600, while the bounding-box reading produces 800×400, which fits inside what you asked for and keeps the picture looking right.

This tool takes the bounding-box reading whenever the aspect ratio is locked, and reports the dimensions it actually produced rather than the ones requested. That distinction is why the output figures are shown for every file. When you genuinely want the target-shape reading, unticking the lock gives it to you, and the preview will show the distortion honestly rather than quietly cropping to hide it.

The third option, and often the best one, is to constrain only one side. Setting a width and leaving the height blank says "make it this wide, whatever that implies" — which is what a page layout usually needs, and it removes the ambiguity entirely.

Why enlarging disappoints

Reducing an image is a well-posed problem: several source pixels are averaged into one output pixel, and the information that survives is a genuine summary of what was there. Enlarging is the reverse and is not well-posed at all. The extra pixels have no source, so they are interpolated — estimated from their neighbours by the browser's built-in smoothing. The result is plausible, but it contains no detail that was not already in the file.

In practice that means a small image scaled up looks soft, and text or fine edges within it develop a faint halo. There is no setting here or anywhere else in a browser that changes this; the specialised upscalers that do better are machine-learning models inventing detail that is convincing rather than correct, which is a different tool with different caveats. If you need a larger image, re-exporting from the original source at the size you want will always beat enlarging a small copy.

What this tool does not do

It resizes, and it does not crop. Cropping changes which part of the picture you keep; resizing changes how many pixels describe the part you already have. Fitting a landscape photograph into a square profile picture is a cropping job, and doing it by unlocking the aspect ratio will squash faces rather than frame them — the image cropper on this site is the tool for that, and the two are commonly used in sequence.

It also does not target a file size. If your constraint is "under 200 KB" rather than "800 pixels wide", the image compressor is the tool for that — it pairs the quality slider with a live before-and-after size comparison so you can find the setting that meets the limit. The two tools share the same local canvas pipeline and the same privacy properties, and they are separate because the question each answers is genuinely different.

Frequently asked questions

Where do my images go when I resize a whole batch?
Nowhere. Every file you load — up to twenty of them — is decoded and redrawn inside the tab, and each result goes straight to your downloads folder. Nothing is queued on a server between steps, which is why there is no progress bar waiting on a network and no size cap beyond what your own machine's memory will hold. Closing the tab discards all of them at once.
Why is the result smaller than the height I asked for?
Because both a width and a height were set with the aspect ratio locked, so the image was fitted inside that box rather than stretched to fill it. Whichever of the two constraints binds first decides the scale, and the other side comes out smaller. That is what people usually mean by "resize to 800×600". If you genuinely want the exact shape, untick the aspect ratio and accept the distortion, or leave one of the two fields blank.
Can I make an image bigger?
Yes, but read the result carefully. Enlarging interpolates new pixels from the ones around them — it cannot recover detail that was never captured, so an upscaled image looks soft and often slightly plastic. Going much beyond about 200% rarely produces something usable. This is the one place the resizer differs from the compressor, which deliberately refuses to enlarge at all.
Does resizing reduce the file size too?
Almost always, and usually by more than a quality setting would. Halving both dimensions removes three quarters of the pixels before the encoder is involved. If file size rather than dimensions is what you are chasing, the image compressor is the better starting point — it pairs a quality slider with a before-and-after size comparison, which this tool does not.
What happens to a transparent PNG?
Transparency survives if the output is PNG or WebP. It cannot survive JPEG, which has no alpha channel, so a background colour control appears as soon as you select JPEG and those pixels are filled with it. Without that fill they would come out black rather than the colour you expect.
Why did a very large size fail?
Browsers cap both the longest side of a canvas and its total pixel count, and going past either produces a blank image rather than an error. Rather than hand you a silently empty file, the tool checks the target size first and reports it. Mobile browsers have considerably lower ceilings than desktop ones, so a size that works on a laptop can fail on a phone.

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