Photos taken on a modern phone are often 4000 pixels wide or more. A blog header, a profile picture, an email signature or a government form usually asks for something much smaller, and often for exact dimensions. Resizing changes the pixel dimensions of an image. That is different from compression, which keeps the dimensions and reduces the file size. This tool does the first of these, directly in your browser, without installing anything.

How to resize an image

1. Click the upload area, or drag an image onto it. A preview appears so you can confirm you chose the right file.
2. Type a number into Width (px), Height (px) or both.
3. Leave the lock checkbox ticked if you want proportions preserved, or untick it to set both sides freely.
4. Press Resize & Download. A file named resized.png downloads, and the page prints the new dimensions and size in kilobytes.

How the lock and the two fields interact

The behaviour is simple but worth understanding precisely, because it explains most surprises:

Notice the third row. If you type both numbers and they do not match the original ratio, the lock does not correct them. To keep proportions, fill in only one of the two boxes. For example, a 4000 by 3000 photo resized to a width of 800 becomes 800 by 600.

Choosing the right size

• Web page content images: a width between 800 and 1600 pixels is enough for most layouts, because few content columns are wider than that.
• Thumbnails: 150 to 400 pixels on the long side, depending on the grid.
• Social media: platforms publish recommended dimensions that change over time, so check the current guidance and enter the exact numbers with the lock off.
• Printing: multiply the print size in inches by the resolution you need. A 6 by 4 inch print at 300 pixels per inch needs 1800 by 1200 pixels.
• Retina or high-density screens: an image shown at 400 CSS pixels wide looks sharper if you supply 800 pixels and let the browser scale it down.

Things to expect from the output

• Enlarging does not add detail. Making a small image bigger spreads the same information over more pixels, so it looks soft. Start from the largest original you have.
• Metadata is not kept. Camera details, location data and similar EXIF information are not carried into the new file, which is a small privacy benefit when you share photos.
• Animated images lose their animation. Only a single frame is drawn onto the output.
• Transparency is preserved because PNG supports it, so logos with clear backgrounds stay clear.
• Very large images may exceed what a phone browser can handle in memory. If the page freezes, try a smaller target size.

Common reasons to resize

• A job portal or government form rejects a photo because it is larger than the allowed pixel size.
• A website is slow because editors uploaded raw camera files. Resizing before upload is the single most effective fix.
• An email signature logo shows huge in some clients. Supplying it at its display size avoids this.
• A product photo has to fit an e-commerce template with fixed dimensions.

How the resizing is done

Your image is loaded into the browser, drawn onto an HTML canvas element at the new width and height, and exported as a PNG file. The scaling algorithm is the one built into your browser, which uses smoothing, so reductions generally look clean. Because everything happens in the page, the file is not uploaded to a server and works even on a slow connection once the page has loaded.

Frequently asked questions