How to resize an image without stretching or blurring it

Step-by-step on Windows, Mac, phones and in the browser, and how to hit an exact pixel size when the shape doesn't match.

A website wants a 1200-pixel-wide banner. A form asks for a photo "no larger than 800×600." A slide deck slows to a crawl because every picture on it is straight off a 12-megapixel camera. It's the same job every time: change how many pixels the image has, without making it look stretched or soft.

The short answer

Open the image in a resizer and set the unit to pixels.
Make sure aspect ratio is locked (sometimes labelled "scale proportionally").
Type the width you need; the height updates itself.
If you need an exact width and height, decide how to handle the shape difference: crop, pad, or stretch.
Save as a copy, so the original stays untouched.

Below are the exact steps for the tools most people already have, then the parts that usually go wrong: exact sizes, enlarging small images, and file size.

How to resize an image on Windows

Photos app. Open the image in Photos, click the … (see more) menu at the top and choose Resize image. Pick pixels or percentage, leave "maintain aspect ratio" on, enter the new width, and save it as a copy. Microsoft moves Photos menus around between updates, so if you don't see this option, use Paint instead.

Paint. Open the image in Paint and choose Resize on the Home tab (or press Ctrl+W). Switch from Percentage to Pixels, keep "Maintain aspect ratio" ticked, type the width, and use Save As so you don't overwrite the original.

How to resize an image on a Mac

Open the image in Preview and choose Tools → Adjust Size. Set the unit menu to pixels, leave Scale proportionally ticked, and type the new width. Keep Resample image ticked too. Without it Preview only changes the print size and leaves the pixel count alone, so the file you upload doesn't actually get smaller. Then use File → Export to save a copy. Apple documents the dialog in itsPreview user guide.

How to resize a photo on iPhone or Android

Phone gallery apps are good at cropping, and the iPhone Photos app has presets like Square and 9:16. But most won't let you type an exact pixel width. That leaves you three options: crop in the gallery and accept whatever size results, use a share option that offers smaller sizes (Mail on iPhone offers Small/Medium/Large when you attach a photo), or open a browser-based resizer, which works the same on a phone as on a laptop. The iPhone guide andAndroid guide cover the built-in options in more detail.

How to resize an image online

A browser resizer is the quickest route when you need an exact number or you're on a device without an editor. The IMAGE SIZE PRO image resizer takes a width, a height, or both. With one value it keeps the proportions; with both it asks how to handle the shape (see the next section). The resizing happens in your browser, so the photo isn't uploaded to a server. If you resize the same few sizes over and over, the resizer remembers the last width and height you used in this browser.

Photoshop and GIMP both do this too (Image → Image Size in Photoshop, Image → Scale Image in GIMP). They're more than you need for a one-off resize, but worth using if you already have them open.

Resizing to an exact size: the maths

Say your phone photo is 4032×3024 and the site wants it 1200 pixels wide. With the aspect ratio locked, the height becomes 1200 × 3024 ÷ 4032 = 900. The result is 1200×900, same shape, no distortion.

Percentages work the same way, but watch what they do to the pixel count. 50% of 4000×3000 is 2000×1500, which is half the width and half the height but only a quarter of the pixels. That's why a 50% resize often shrinks the file far more than people expect.

If you want to work out a size before you resize, for example "what height keeps 16:9 at 1280 wide?", lock the aspect ratio in the resizer and enter just the width; it fills in the matching height.

When the width and height don't match your photo's shape

This is where most resizing problems come from. The slot is square, your photo is 4:3, and you have to decide what gives. There are three honest options:

Crop to fill. The photo is scaled until it covers the whole box, and the overflow is trimmed off. Nothing is distorted, but you lose some of the edges. This is the right choice for avatars and thumbnails, and it's usually worth doing the crop yourself in animage cropper so you pick what gets cut.
Fit inside. The whole photo stays visible and empty bands fill the leftover space (IMAGE SIZE PRO fills them with white). Nothing is lost, but the image doesn't fill the frame.
Stretch. The photo is forced to the exact box and the proportions change. Only use this when a system demands an exact size and won't accept either of the others.

Take a wide landscape going into a 200×200 profile slot. Fit inside gives you a thin strip with white above and below. Crop to fill gives you a square taken from the middle of the scene. Stretch squashes the whole landscape into a square, and anything round turns into an oval.

How to resize without losing quality

Making an image smaller is safe. You're throwing away pixels, but the image will be shown smaller too, so the detail you drop is detail nobody would see at that size. A few habits keep the result crisp:

Start from the original, not from something you've already resized or sent through a messaging app.
Resize once, straight to the final size. Repeated resizing softens the image a little more each time.
Keep the aspect ratio locked unless you really do want the shape to change.
Save photos as JPEG at a high quality setting, and graphics with text or sharp edges as PNG (thePNG vs JPG guide explains why). Theimage quality guide shows how to check for damage.

Why you can't make a small image bigger and sharper

Enlarging is the one direction where quality really does suffer. A 400-pixel image stretched to 1600 pixels has to invent fifteen new pixels for every one it had, by blending the neighbours. Edges go soft and fine texture turns to mush. No setting in an ordinary resizer can fix that, because the detail was never captured.

A small enlargement (say 10–20%) often passes unnoticed. Beyond that, it's worth looking for a larger original, whether that's the camera file, the full-size download, or the source of the logo.

Pixel dimensions vs. file size

These are easy to mix up. Pixel dimensions (width × height) describe how much detail an image holds. File size (KB or MB) is how much storage it takes, which depends on dimensions and on format and compression. Resizing changes the first and usually shrinks the second as a side effect, but it won't land you on an exact number of KB.

So if a form says "under 100 KB", resize to sensible dimensions first, then compress. Fewer pixels need less compression to reach a given size, so the photo stays sharper. The guide togetting a photo under a KB limit walks through that, and how image compression works explains the trade-off.

Common mistakes

Typing both width and height with the ratio unlocked. This is the number-one cause of stretched faces. Type one value and let the other follow.
Changing DPI and expecting the file to shrink. A DPI or resolution field only changes the print size unless the pixels are resampled. Check the width and height in pixels afterwards.
Overwriting the original. Save a copy. You can't un-resize a photo.
Assuming a "standard" size. Social platforms and upload forms each have their own numbers, and they change. Check the size the platform actually asks for; for social media, thesocial image size guide is a starting point.

Before you use the resized image

Width and height in pixels are what you needed (check the file's properties).
Nothing looks stretched: faces, circles and text keep their normal shape.
Nothing important was cropped off the edges.
If there's a file-size limit, the file is under it.
The original is still saved somewhere.

Resizing questions

How do I resize a picture to a specific size in pixels?

Open it in a resizer that takes pixel values (Windows Photos or Paint, Preview on a Mac, or a browser tool), switch the unit to pixels, and type the width you need. With the aspect ratio locked, the height follows automatically. If you need an exact width and height that don't match the photo's shape, you'll have to choose between cropping, padding, or stretching.

How do I resize an image without losing quality?

Making an image smaller keeps it looking sharp. You lose pixels, but at the smaller display size you won't see them go. Work from the original rather than a copy that's been resized or compressed before, keep the aspect ratio locked, and save photos at a high JPEG quality. Making an image larger is the part that costs quality, because no resizer can add detail that wasn't captured.

Can I make a small image bigger without it getting blurry?

Not with ordinary resizing. Enlarging spreads the existing pixels over a bigger area and fills the gaps by blending neighbours, so edges go soft. A modest enlargement can look acceptable; a large one won't. If you need a bigger image, find a larger original first.

What does 'maintain aspect ratio' or 'scale proportionally' mean?

It keeps the width and height in the same proportion as the original, so when you change one the other is recalculated for you. Leave it on unless you deliberately want to distort the image. Turning it off is the usual cause of stretched faces and squashed logos.

Does resizing an image reduce its file size?

Usually by a lot. File size roughly follows pixel count, and halving the width and height leaves a quarter of the pixels. If you need to hit a specific size in KB, though, resizing alone won't land on an exact number. Resize first, then compress to the target.

How do I resize a JPEG without changing it to another format?

Most resizers save in the same format you opened unless you choose otherwise. In Preview and Windows Photos the result stays a JPEG. In a browser tool, keep the output format set to the original or to JPG. Every JPEG save re-compresses the image slightly, so resize once from the original rather than resizing a resized copy again.