How to compress an image
- Add your images. Drag them into the box or tap Choose Images. You can add many at once.
- Choose how to compress. Use Quality for the usual "smaller but still sharp" result, or Target size when a website says the file must be under a limit such as 50 KB.
- Compress and download. Click Compress. Each file shows its old and new size. Download them one by one or all together as a ZIP.
Compress an image to 20 KB, 50 KB, 100 KB or 200 KB
Job portals, exam and university applications, passport and visa forms and government websites often only accept photos and signatures under a fixed size. Pick Target size, tap a preset or type your own limit, and ConvertKettle finds the highest quality that fits.
If the limit is very small, quality alone isn't enough, so the tool also reduces the picture's width and height until it fits. You'll see the new dimensions next to the file. Need an exact size in pixels as well? Use Resize Image first, then compress.
Which format should I choose?
| Format | Best for |
|---|---|
| JPG | Photos. Small files that open everywhere. No transparency. |
| PNG | Logos, screenshots and graphics with transparent backgrounds. |
| WebP | Websites. Usually 25–35% smaller than JPG at the same quality, with transparency. |
Same format keeps each file's type. PNGs are compressed by reducing the number of colors, the same trick popular PNG compressors use, so transparency is kept.
Frequently asked questions
How do I compress an image to a specific size like 50KB?
Choose Target size, type 50 and select KB, then click Compress. The tool finds the best quality that fits under 50 KB, and only makes the picture smaller if it has to.
Does compressing reduce image quality?
A little, but at the default setting the difference is very hard to see while the file usually becomes 50–80% smaller.
Are my images uploaded?
No. Compression happens inside your browser and your images never leave your device.
Can I compress PNG files?
Yes. PNG images are compressed by reducing the number of colors, which keeps transparency and the PNG format.
Why did my image get smaller in pixels?
If an image can't reach your target size even at low quality, the tool reduces its dimensions until it fits. The new size is shown next to the file.
Image size limits you'll run into
Most "file too large" errors come from a handful of common limits. Here's what to aim for:
| Where the image is going | Typical limit | Suggested setting |
|---|---|---|
| Gmail attachment | 25 MB per email | Quality 70–80% for a batch of photos |
| Outlook.com attachment | 20 MB per email | Quality 70–80% |
| Job portals and online applications | Often 100 KB – 2 MB per file | Target size, e.g. 200 KB |
| School, exam and government forms | Often 20 KB – 500 KB for photos and signatures | Target size, exactly as the form states |
| Images on your own website | No hard limit, but slow pages rank lower | Under 200 KB each, WebP if possible |
Website and form limits change, so always check the exact number on the page you're uploading to.
Lossy vs. lossless compression
Lossy compression (used for JPG and WebP) throws away fine detail your eye barely notices – tiny color variations in skies, skin and foliage. That's why a photo can shrink by 70% or more and still look the same on screen. Push the quality too low, though, and you'll start to see blocky patches and halos around edges.
Lossless compression keeps every pixel exactly as it was, so savings are much smaller. PNG is lossless, which is why ConvertKettle compresses PNGs by reducing the number of colors instead – a technique that works especially well for logos, icons, screenshots and illustrations.
Tips for the smallest possible file
- Resize first. A 12-megapixel phone photo is about 4000 pixels wide. If it will only be viewed on screen, resizing it to 1600–2000 pixels cuts the file size dramatically before compression even starts.
- Pick the right format. Photos belong in JPG or WebP. Screenshots with text and flat colors often stay sharper and smaller as PNG.
- Crop away empty space. Fewer pixels means a smaller file – crop out walls, sky or desk you don't need.
- Compress once. Each round of JPG compression loses a little more detail, so keep your original and compress from it.