How to Compress Images Online for Free

PDFly guide · Updated October 2026

Big photos slow down websites, fill up email attachments and eat storage. Compressing them can cut the file size by half or more with little visible difference. PDFly's Compress Images tool does it for many images at once, right in your browser, so your photos never leave your device.

How to compress images step by step

1. Add your images. Drop JPG, PNG or WEBP files onto the page, or press Choose images. You can add as many as you like, and add more later.
2. Pick a level. Choose High, Medium or Low compression. The results update straight away, so you can compare.
3. Check the savings. Every image shows its size before and after, plus the percentage saved.
4. Download. Save one image, or press Download all to get a single zip.

High, medium or low compression?

• High compression gives the smallest files. Very large photos are also scaled down to 1600 px on the long side. Good for websites, chat apps and email.
• Medium compression is the best balance for most photos: a big size cut that still looks sharp, with a limit of 2560 px.
• Low compression keeps the highest quality and only trims the size lightly. Choose it for photos you may print or edit again.

What happens to each format

• JPG stays JPG, saved again at a lower quality setting.
• PNG files without transparency become JPG, which is usually far smaller for photos. PNGs with transparency are saved as WEBP so the see-through areas are kept.
• WEBP stays WEBP.
• Prefer one format for everything? Use the Output format menu to choose JPG or WEBP.
• If an image cannot be made smaller, PDFly keeps the original, so a file never gets bigger.

Tips for the best result

• Start with Medium. Move to High only if you need the files even smaller.
• Screenshots and graphics with sharp text can look softer at High, so use Medium or Low for them.
• Keep your original photos. Compression is permanent for the downloaded copy.
• Working with PDFs instead? Use Compress PDF.