How to Compress Images Without Visible Quality Loss
Shrink JPEG, PNG and WebP files for websites, email and uploads: how size, quality and format affect file size, with a free in-browser image compressor.
Published
Free tool: Image CompressorLarge images slow down websites, bounce off email attachment limits and get rejected by upload forms. The good news is that most photos can be made several times smaller without anyone noticing the difference. Three things control the file size: the image's dimensions, the compression quality and the file format. This guide explains each one and shows how to compress images with the free Image Compressor, which works in your browser.
Lossy vs lossless compression
- Lossy compression (JPEG, and WebP in its usual mode) throws away detail the eye is unlikely to notice. You choose the trade-off with a quality setting: lower quality, smaller file.
- Lossless compression (PNG) keeps every pixel exactly. Nothing is lost, but photos stay large.
"Without losing quality" in practice means without visible loss. At a sensible quality setting, a lossy photo looks the same to a viewer at a fraction of the size.
1. Resize to the size you actually need
Phone cameras produce images around 4000 × 3000 pixels, or 12 megapixels, far more than a screen shows. File size grows with the number of pixels, so resizing is usually the biggest single saving:
| Longest side | Example dimensions | Pixels | Compared with 4000 × 3000 |
|---|---|---|---|
| 4000 px | 4000 × 3000 | 12.0 million | 100% |
| 1920 px | 1920 × 1440 | 2.8 million | 23% |
| 1280 px | 1280 × 960 | 1.2 million | 10% |
| 800 px | 800 × 600 | 0.5 million | 4% |
As a rule of thumb, 1920 pixels covers full-width website images and Full HD screens, 1280 pixels suits images inside articles and emails, and 800 pixels is plenty for thumbnails and product listings. Keep the full-size original for printing.
2. Pick a sensible quality setting
For JPEG and WebP, a quality of about 75% to 85% is the sweet spot for most photos: the file shrinks dramatically and the difference is hard to see. Below about 60%, compression artifacts start to show, such as blocky patches in smooth areas like skies and halos around sharp edges.
Two habits help:
- Compress from the original, not from an already compressed copy. Each round of lossy compression removes a little more detail.
- Check the result at its real size before you replace the original.
3. Choose the right format
| Format | Best for | Transparency | Notes |
|---|---|---|---|
| JPEG | Photos | No | Works everywhere, including old software and email |
| PNG | Screenshots, logos, graphics with text | Yes | Lossless; very large for photos |
| WebP | Photos and graphics on websites | Yes | Often 25% to 35% smaller than a comparable JPEG; supported by all modern browsers |
A common mistake is saving a photo as PNG: it can be several times larger than a JPEG that looks the same. The opposite mistake is saving a logo with a transparent background as JPEG, which fills the transparent areas in. For websites, WebP is usually the best choice for both photos and graphics.
How to compress images with Graph Maker
- Open the Image Compressor.
- Add your images. Drag them onto the page or click to choose files. It accepts JPEG, PNG, WebP and BMP, and you can add several at once. You can also paste a direct link to an image on the web.
- Set the quality. The slider runs from 10% to 100% and starts at 80%, a good default for photos.
- Choose the output format: keep the original format, or convert to JPEG, PNG or WebP. Converting PNG photos to WebP or JPEG usually saves the most.
- Choose the maximum width or height: 1920 px (Full HD), 1280 px (HD), 800 px (web), or the original size up to 4K. Images keep their proportions.
- Click Compress Images. Each file shows its original size next to its new size, so you can see how much you've saved.
- Download each image separately, or click Download All as ZIP.
Images you add from your device are compressed in your browser and never uploaded to a server, so private photos stay on your computer.
Settings for common uses
- Website images: WebP, 1920 px or less, 75% to 85% quality. Smaller images make pages load faster, especially on phones.
- Email attachments: JPEG at 1280 px. Many email services cap attachments at 20 to 25 MB per message, and recipients appreciate smaller files.
- Upload forms with a size limit: if a form demands a file under a set size, such as 100 KB, use the Resize Image tool, which can aim for a target file size.
- Social media: platforms recompress your uploads anyway, so upload at the size they recommend instead of compressing heavily first.
- Printing: skip heavy compression and keep the full resolution.
Common mistakes to avoid
- Compressing the same JPEG again and again. Keep an original and always work from it.
- Upscaling small images. Making an image bigger doesn't add detail; it only makes the file larger.
- Using JPEG for screenshots of text. Sharp text gets fuzzy halos; PNG or WebP keeps it crisp.
- Losing transparency. Logos and icons with transparent backgrounds need PNG or WebP. To change a file's format without compressing it, use the Image Converter.
Frequently asked questions
Does compressing an image reduce its quality?
Lossy compression removes some detail, but at a quality of around 75% to 85% the difference is usually invisible at normal viewing sizes. Lossless compression and resizing to the size you need don't make the image look worse on screen.
What's the best quality setting for JPEG?
Around 75% to 85% for photos you'll show on screens. Go higher for images that will be edited further or printed, and avoid going much below 60%.
Why did my PNG barely get smaller?
PNG is lossless, so the quality setting has little effect on it. Resize it to smaller dimensions, or, if it's a photo, convert it to WebP or JPEG for a much bigger saving.