How to use the Resize Image tool
- Drop a JPG, PNG or WebP image into the box, or tap to pick one from your device.
- Choose how to resize: by pixels, by percent, or by a target file size in KB.
- Pick an output format, or keep the original one.
- Press Resize image, check the preview and download your new file.
Why resize images?
Large photos straight from a phone camera are often 4000 pixels wide and several megabytes in size. That is far more than a website, an email or an online form needs. Oversized images make pages slow, fill up mailboxes and get rejected by upload forms that set a strict limit. Resizing gives you a file that fits the job: sharp enough to look good, small enough to load fast.
Pixels, percent or kilobytes
Use pixel mode when a platform asks for exact dimensions, such as 1080 x 1080 for a square social post or 600 x 600 for a passport-style photo. Percent mode is quick when you simply want everything half the size. KB mode is made for application forms that say "maximum 100 KB" or "under 20 KB": the tool tries different quality levels and, if needed, reduces dimensions slightly until the file fits.
Keep the aspect ratio
With the lock switched on, changing the width updates the height automatically, so faces and products never look stretched. Turn it off only when you really need a fixed box shape, or use the crop tool first to cut the picture to the right proportions.
Private by design
Many online resizers send your picture to a server. This one does the work with your browser's own graphics engine, so personal photos, ID scans and client work stay on your computer or phone. It even keeps working if your connection drops after the page has loaded.
Resolution vs file size
People often mix up two different things. Resolution is the number of pixels, for example 1920 x 1080. File size is how much storage the image takes, measured in KB or MB. Lowering the resolution almost always makes the file smaller, but you can also keep the resolution and only reduce the file size with compression. This resolution changer lets you control both, so you can pick whichever an upload form or website actually asks for.
Quick reference sizes
Some sizes come up again and again: 1080 x 1080 for square social posts, 1280 x 720 for video thumbnails, 600 x 600 for US visa and passport photos, and around 1200 to 2000 pixels wide for blog images. For forms with a size limit, try our presets for 20 KB, 50 KB and 100 KB, which load the right settings for you.
Frequently asked questions
Is this image resizer really free?
Yes. Every tool on ResizeImage.app is free to use with no sign-up and no watermark.
Can I resize an image to a specific KB size?
Yes. Choose "By file size (KB)", enter the target, and the tool adjusts quality and, if needed, dimensions until the file is at or under that size. Very small targets are saved as JPG or WebP because PNG cannot be compressed by quality.
Will resizing reduce quality?
Making an image smaller keeps it sharp. Enlarging beyond the original size can look soft because new pixels must be estimated.
Are my photos uploaded?
No. The image is processed inside your browser and is never sent to our server.
What is the difference between resizing and compressing?
Resizing changes the pixel dimensions. Compressing keeps the dimensions and lowers the file size by saving with a lower quality. Our KB mode combines both when needed.
How do I resize image resolution without losing quality?
Reduce the size rather than enlarging, keep the aspect ratio locked, and save as PNG or a high-quality JPG.