How to Resize and Compress JPEG Images Online

An oversized photo can fail an upload limit, slow down a page or get rejected by a form that expects specific dimensions. A JPEG compressor and resizer solves this in two separate steps. Resizing lowers the pixel dimensions, and compression lowers the quality setting used to encode those pixels. This guide covers both steps in a browser-based tool and shows how to check the result.

Before you start

• Keep a copy of the original file. JPEG compression is lossy, so detail removed during export cannot be recovered from the smaller file.
• Find out what the destination requires: exact width and height in pixels, a maximum file size, or both.
• Check the image's current pixel dimensions in your operating system's file properties or in an image viewer.
• Decide whether you need transparency. JPEG does not support it, so transparent areas from a PNG or similar source will be filled with a solid color.
• Find out where the processing happens. Some online tools work entirely in the browser, and others upload your file to a server. Read the tool's own privacy and file-handling statements before you upload personal photos or documents, and do not assume files are deleted unless the tool says so.

If the tool's description does not make the processing location clear, treat the file as uploaded. Your browser's developer tools can show network requests made while the image is processed, and these can help you confirm what the page sends.

Step-by-step instructions

Interfaces differ between tools, but most combined JPEG resizers and compressors follow the same order. Resize first, then compress. Reducing the pixel count usually shrinks the file size more than lowering the quality does, and it leaves you more room to keep the quality setting high.

• Open the tool and add your image. Most tools accept drag and drop or a file picker.
• Find the resize option. Depending on the tool, it may be labelled resize, dimensions or size.
• Choose how to set the new size. Pixel values give exact results. A percentage is quicker when you only need the image smaller.
• Keep the aspect ratio locked, usually shown as a lock or link icon between width and height, then enter one value and let the tool calculate the other.
• If you need exact width and height that do not match the original proportions, choose a crop or fit option, if the tool offers one, rather than stretching the image.
• Set the output file format to JPEG if the tool offers a choice.
• Adjust the quality or compression setting. Start high and lower it gradually. If the tool has a target file size mode, enter the size limit you need instead.
• Look for optional settings such as keeping or removing metadata and progressive encoding. Removing metadata reduces the file size slightly and strips camera and location data.
• Process the image and download the result under a new file name so the original stays untouched.

Quality scales are not standard. A value of 80 in one tool may not produce the same result as 80 in another. Judge the setting by the output itself, not by the number.

Check the output

• Open the downloaded file's properties and confirm that its pixel dimensions match what you entered.
• Compare the file size with the destination's limit.
• View the image at 100 percent zoom. Look for blockiness in flat areas such as the sky or skin, color banding in gradients, and halos around sharp edges and text.
• Compare the image with the original side by side to make sure nothing looks stretched, which means the aspect ratio changed.
• If the source had transparency, check that the background fill color is acceptable.
• Upload the file to the actual destination when that is the final test, because some services resize or recompress images again on their side.

Common problems and next steps

The image looks squashed or stretched. The aspect ratio was unlocked, or the width and height you entered do not match the original proportions. Go back to the original, lock the ratio, and use crop or fit to reach the exact dimensions.

The file is still too large. Reduce the pixel dimensions further before lowering quality again. Very low quality settings cause visible artifacts faster than a smaller size does. Removing metadata can also help a little.

The image looks soft or blurry. Enlarging a small JPEG to bigger pixel dimensions cannot add detail. Start from a higher-resolution original instead.

Quality keeps getting worse. Each time a JPEG is saved again, more detail is lost. Always resize and compress from the original file, not from a previously compressed copy.

The photo appears rotated after processing. Phone photos often store orientation as metadata. If a tool removes that data without rotating the pixels, the image may display sideways. Rotate the image in the tool before export, or try keeping the metadata.

The background turned white or black. The source contained transparency, which JPEG cannot store. If you need a transparent background, export to a format that supports it, such as PNG or WebP, and check that the destination accepts that format.