How to Compress Images Without Losing Quality

Photos from a modern phone are often 3 to 10 MB each. That’s fine on your phone, but too much for a website, an email attachment or an online form. Large images make pages load slowly, use up storage and data, and can hurt how your site ranks, because page speed is part of how Google judges a page.

The good news: most images can be made two to five times smaller without anyone noticing a difference. This guide explains how image compression works, the best settings for each format, and how to do it for free with the Image Compressor.

What “without losing quality” really means

There are two kinds of compression:

• Lossless compression stores exactly the same pixels in less space. Nothing changes, but the saving is usually small.
• Lossy compression drops detail the eye barely sees, such as tiny variations in colour. The saving is much bigger.

“Without losing quality” in practice means without visible loss: the file loses some data, but the picture looks the same at normal size. The trick is to find the setting where the file is as small as possible before you can see a difference. That’s exactly what the before-and-after slider in the compressor is for.

How to compress images, step by step

1. Open the Image Compressor. It works in any modern browser, on a computer or a phone.
2. Add your images. Click Select images or drop files onto the box. You can mix JPEG, PNG, WebP, GIF, SVG and HEIC, up to 50 at once. Each file’s format is recognised automatically.
3. Click Compress. Every image is compressed with settings that suit its format, and its card shows how much smaller it got.
4. Check and fine-tune. Click an image to compare before and after with the slider. Change the Quality, Colors or Decimals (and the Max size for photos), then click Apply. Adjusting an image you’ve already compressed is free.
5. Save. Use Save on one image, or Save all to download everything in a ZIP file.

The best settings for each format

JPEG and WebP: quality

For photos, the quality setting is what matters. The compressor starts at 75, a good balance for most photos. Between 60 and 80 photos usually look the same as the original; below 50 you start to see blocky areas in skies and soft gradients. For images where every detail counts, such as product photos, stay around 80.

PNG: number of colours

PNG images are made smaller by reducing them to a limited palette of colours, the same technique popular PNG optimizers use. The compressor starts at 256 colours, which is usually invisible on screenshots and illustrations. Logos, icons and simple graphics often look perfect with 32 to 64 colours, and the files get much smaller. Photos saved as PNG need more colours; for those, converting to JPG is usually better (see below).

GIF: number of colours

GIFs can have at most 256 colours anyway. The compressor starts at 128 and keeps animations moving. Fewer colours make smaller files, but watch out for banding in smooth gradients.

SVG: decimals

SVG files are code. The compressor removes editor data and comments and rounds numbers to 3 decimals. Going down to 2 is usually invisible; 0 or 1 can make curves look slightly off.

Resize: the biggest saving of all

A 4,000-pixel-wide photo has four times the pixels of a 2,000-pixel one, and the file is roughly four times larger. But very few places ever show a photo that big: most websites, emails and social networks display images under 2,000 pixels wide.

For JPEG, WebP and HEIC photos, the compressor has a Max size option that limits the longest side to 3840, 2560, 2048, 1600, 1280 or 1024 pixels. For a website or an email, 2048 or 1600 is plenty, and it often saves more than the quality setting. Keep Original size for photos you want to print.

Choose the right format first

• Photos: JPEG or WebP. A photo saved as PNG can be five times bigger than necessary; convert PNG to JPG first, then compress.
• Websites: WebP is usually 25 to 35% smaller than JPEG at the same quality, and every modern browser supports it. Convert JPG to WebP for your own site.
• Logos, icons and screenshots: PNG, or SVG for logos and icons when you have one.
• iPhone photos (HEIC): the compressor saves them as JPG so they open everywhere. More about this in how to convert HEIC to JPG.

Is it private?

Yes. Images are compressed inside your browser and are never uploaded. As a bonus, compressed JPEG, WebP and PNG files no longer contain hidden photo details such as the camera model, the date or the GPS location, which makes them smaller and safer to share.

Frequently asked questions

Will compressing make my images look worse?

Not with sensible settings. The starting values are chosen so the difference is hard to see, and you can compare before and after on every image. If you see a difference, raise the quality or the number of colours and click Apply.

Why is one of my images not smaller?

Some images are already well compressed. If compressing would not make a file smaller, the compressor keeps the original and marks it Already optimized, so you never end up with a bigger file.

Can I compress many images at once?

Yes. Add up to 50 images, even of different formats, compress them in one go, and download them together as a ZIP file.