Image Resizer
Resize images to any dimension
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
Thumbnail selected — upload an image to apply it.
Drag & drop files here
or browse to upload
Supports PNG, JPG, WebP up to 20MB
Processed in your browser - your file never leaves this device.
About this tool
The Thumbnail size is 300 x 300 pixels, a square 1:1 frame. Drop an image on this page and the preset is already applied - there is nothing to type in. Small and square - fine for a grid, and light enough that a page full of them still loads quickly. Small enough that a page full of them still loads quickly, which is the only real constraint on a thumbnail. The image never leaves your computer - the resize runs in the browser, which also means there is no queue and no file-size cap. Feeding in a different aspect ratio means something gets cut. The preview shows exactly what, so you can reposition instead of discovering it after posting.
How to use this tool
- Drop your image inAny JPG, PNG or WebP. Nothing is uploaded - your browser reads the file directly.
- It resizes to 300 x 300 pixelsThe Thumbnail preset is already selected on this page, so there is nothing to type in.
- Check the preview and downloadThe preview shows the exact crop. Reposition if you need to, then save as JPG, PNG or WebP.
Key features
- No limit on how many images you resize.
- Export as JPG, PNG or WebP, whichever the platform prefers.
- Runs in your browser - no upload, no account, no watermark.
- Resizes to exactly 300 x 300 pixels, the current Thumbnail size.
- Live preview, so you see the crop before downloading instead of after.
Common uses
- Making small preview images for a site or app.
- Fixing an image a platform rejected for being the wrong dimensions.
- Preparing a batch at 300 x 300 pixels before a scheduled post.
- Getting a correctly sized image without opening a full editor for a 30-second job.
- Resizing on a phone without installing an editing app.
Tips for better results
- Start from the largest original you have. Scaling up to 300 x 300 pixels from something smaller looks soft, and nothing undoes that.
- Check the result on the platform itself - feed thumbnails are often cropped again from the size you upload.
- PNG keeps text and sharp edges crisp at this size; JPG is smaller for photographs.
- Crop to 1:1 before resizing when the subject matters - then you choose what is lost rather than the tool.
Mistakes to avoid
- Re-saving the same JPG over and over. Each save loses a little more detail, permanently.
- Assuming another platform at the same pixel size behaves identically. Small enough that a page full of them still loads quickly, which is the only real constraint on a thumbnail.
- Scaling a small image up to hit the pixel count. The file gets bigger; the detail does not come back.
- Letting the image stretch instead of keeping the ratio. A squashed face is more obvious than a tight crop.
Frequently asked questions
300 x 300 pixels - a square 1:1 frame, 0.1 megapixels.
Drop it onto this page. The Thumbnail preset is already selected, so it resizes straight to 300 x 300 pixels and shows the crop before you download.
No. The resize uses your own device image engine, so files never leave your computer.
JPG for photographs, PNG when there is text or transparency, WebP when the platform accepts it and you want the smallest file.
Yes. It runs in the browser, so it works on iPhone and Android as well as desktop, with no app to install.
No. It keeps the 1:1 ratio and shows what will be cropped, so you can reposition before downloading rather than finding a bad crop afterwards.
Small enough that a page full of them still loads quickly, which is the only real constraint on a thumbnail.
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