Resize images online free, one or a hundred at a time

Resizing and compressing are not the same thing

These two get muddled constantly, and knowing the difference solves most picture problems in one move.

Resizing changes how many pixels the image contains. A photo that was 4000 pixels wide becomes 1000 pixels wide, and there are genuinely fewer pixels afterwards. Compressing keeps every pixel but describes them less precisely, trading detail for file size.

Here is the part people miss. Resizing is by far the bigger lever. Halving the width also halves the height, so you remove roughly three quarters of the pixels in one step. No quality setting comes close to that. If a photo is too heavy for a web page, the first question is not how hard to squeeze it, it is whether it needs to be 4000 pixels wide at all.

Most of the time it does not. It is going into a space 800 pixels across, and the browser was shrinking it on arrival anyway. You were paying for pixels that were thrown away before anyone saw them.

Three modes, because they do different jobs

Fit inside a box

The whole picture is kept and made as large as it can be inside the dimensions you give. Nothing is cropped and nothing is lost. A wide photo put into a square box comes out wide and shorter than the box, which is exactly right when the whole image matters.

You can give just a width, just a height, or both. Giving only a width is the most common thing anyone does with a resizer: make everything 1200 pixels across and let the height fall where it may.

Exact size

You get precisely the dimensions you asked for. The picture is scaled until it fills the frame and whatever hangs over the edges is trimmed away from the middle outwards. Use it when a layout demands a specific shape: a square product thumbnail, a link preview at 1200 by 630, an avatar.

The trade is that something gets cut. Feeding a tall portrait photo into a wide banner shape will lose the top and bottom, and that may include somebody’s head. Check the result rather than assuming.

By percentage

Everything scales by the same amount, with no target size at all. Useful when you have a folder of pictures at different sizes and want them all reduced proportionally rather than forced to one dimension. Fifty percent means half the width and half the height, which is a quarter of the pixels.

What size should things actually be

Match the size to the space the picture will fill, and stop there. Anything beyond that is weight carried for nothing.

One adjustment worth knowing. Screens with high pixel density show images more sharply if the file has more pixels than the space it occupies. If sharpness on those screens matters to you, supply roughly double the display width. If file size matters more, do not. Both are defensible, and doubling everything by reflex is how pages end up slow.

Enlarging, and why it disappoints

The option not to enlarge smaller pictures is switched on by default, and it is worth understanding why rather than turning it off in frustration.

A 400 pixel image contains 400 pixels of information. Asking for 1600 does not create the missing detail, because that detail was never captured. All that happens is the same information gets spread across sixteen times as many pixels, and the result looks soft and slightly smeared. Enlarging never adds sharpness, and no tool changes that.

If you genuinely need a bigger version, the only real answers are to find the original file at a higher resolution, or take the photograph again. Where enlargement can be acceptable is small steps on already sharp images, or output going somewhere it will be viewed from a distance, such as a poster.

Why edges look ragged in some resizers

There is a technical detail here that explains a great deal about why the same photo comes out looking fine from one tool and speckled from another.

When you shrink an image dramatically in a single step, most drawing code samples a scattering of the original pixels and ignores everything in between. On a photo of a brick wall or a striped shirt, that produces the crawling, sparkly texture people describe as looking cheap. Fine text turns into fuzz. Thin lines break up.

Reducing in halving steps instead means every pixel contributes to the result. It takes a little longer and it is why the pictures that come out of this page look properly resized rather than merely smaller. It matters most on exactly the images people care about: screenshots with text, product photos with detail, anything with fine repeating pattern.

Formats, and what to pick

• JPEG for photographs. It opens everywhere, including old software and stubborn upload forms. It cannot hold transparency.
• WebP when you control where the picture goes. Roughly a quarter to a third smaller than JPEG at the same visual quality, and it keeps transparency. Every current browser supports it.
• PNG for screenshots, logos, diagrams and anything with crisp text or hard edges. Poor for photographs, where it can easily be five times larger than it needs to be.

Leaving the format on the sensible setting handles the common cases: photographs become JPEG, and anything with see through areas keeps a format that can hold them. That last part matters. Pushing a transparent PNG through JPEG turns every transparent pixel white, and people usually discover this after placing the file somewhere.

Working through a batch

The same settings apply to every picture you add, which is the point of doing it in bulk. A few habits make it painless.

• Work on copies. Resizing is one directional. Keep your originals somewhere safe, because the pixels you remove are not coming back.
• Group by orientation. A batch containing both portrait and landscape photos will behave differently under exact size mode, because the crop takes from different places. Run them separately if the framing matters.
• Check the first result properly. The line under the controls tells you what your first picture will become before you start. Read it. It catches the wrong number more often than you would think.
• Look at the crops. In exact size mode, glance at each thumbnail afterwards. Centred cropping is right most of the time and wrong exactly when the subject is off to one side.

Resize first, then compress

If your goal is a smaller file, the order matters. Resize to the dimensions you actually need, then compress what is left. Doing it the other way round means you carefully compressed pixels you were about to throw away.

In practice, resizing alone often gets you under the limit. When it does not, our image compressor handles the second half. If the picture needs its background removed as well, do that first with the background remover, since a cutout saved as PNG is usually large and benefits from being resized afterwards rather than before.

Nothing here is uploaded

Most online resizers work the same way. Your pictures go to a server, get processed there, and come back as a download. For holiday photos, fine. For product shots before launch, identity documents for an application, photographs of your children or scans of paperwork, it means the files sat on hardware you cannot inspect for as long as somebody else’s policy says.

This page uses your browser’s own image decoder to open each file and writes the new versions in the same tab. Nothing goes out. Open the network panel in your developer tools and watch it run if you would rather see that than be told it. It also means the tool keeps working when your connection drops, and there is nothing to delete afterwards because nothing was ever stored.

No account, no daily allowance, no watermark, and no limit on how many pictures you put through it. The rest of the image tools cover whatever comes next.