Image Compressor
Shrink image file size without losing quality.
Processed in your browser — never uploaded, discarded after download.
What is Image Compressor?
Image Compressor is a free online tool that shrinks a photo to a target file size — 100 KB, 200 KB, 500 KB, or 1 MB — right in your browser. Instead of guessing quality settings, it automatically finds the highest JPEG quality that stays under your limit, so the result is as sharp as possible.
Key features
- Target file sizes: 100 KB, 200 KB, 500 KB, or 1 MB
- Automatically picks the highest JPEG quality under your limit
- Shows the compressed size and how much smaller it got
- Outputs a ready-to-upload JPG
- Works with large photos straight from your camera or phone
How to compress an image to a target size
Some upload forms reject anything over a hard KB limit. Instead of nudging a quality slider and re-checking the file size, this tool works backwards from the number you actually care about: pick a ceiling — 100 KB, 200 KB, 500 KB, or 1 MB — and it finds the sharpest image that fits under it.
How it hits the target
The tool runs a binary search on JPEG quality. It encodes the image at a mid quality, checks the resulting byte size, and then narrows in — if the file came out under your limit it tries higher quality, if it's over it backs off — repeating eight times to converge on the best quality that still stays under the cap. That's why the result is genuinely as close to your budget as JPEG allows, rather than a fixed "medium" preset that lands anywhere.
If even the lowest quality overshoots — which happens with a huge image and a tiny target — it falls back to a minimum-quality encode so you still get a file. In that case, resizing first is the real fix (see below).
Why the output is always a JPG
Compression targets rely on JPEG's quality dial, so the download is a .jpg named yourfile_compressed.jpg. One consequence to know: JPEG has no transparency, so if you feed in a PNG with transparent areas, those pixels are flattened onto a white background. For a logo that needs to stay transparent, this isn't the right tool — use the Image Converter instead.
When to resize before compressing
File size and pixel dimensions are different things. A 6000×4000 photo straight from a phone carries far more detail than a 100 KB budget can hold, so squeezing it that small forces heavy quality loss and visible blockiness. If the destination doesn't need full resolution, run it through the Image Resize tool first (say, down to 1600 px wide), then compress — you'll hit the same target with a much cleaner picture.
Reading the result
After compressing, the tool shows the original size, the new size, and the percentage saved, so you can confirm you're under the limit before uploading. For the common case of a fixed 100 KB cap with no options to choose, the Compress Image to 100KB tool does the same thing in a single click.
Things worth knowing
- Every quality attempt is encoded locally in your browser — the photo is never uploaded, even for a large file.
- Because it's on-device, there's no server-imposed size limit; the practical ceiling is your device's memory.
- The tool controls file size, not dimensions — the image keeps its original width and height unless you resize it separately.
Frequently asked questions
- What format do I get back after compressing?
- Always a JPG, named yourfile_compressed.jpg, because the size targeting works by tuning JPEG quality. If your source is a PNG with transparency, those transparent pixels are flattened onto white, so for a logo that must stay transparent use the Image Converter instead.
- How does it land so close to my target size?
- It runs a binary search on JPEG quality, encoding the image, checking the byte size, and narrowing between roughly 5% and 97% quality over eight rounds to find the sharpest version that still fits under your cap. That beats a fixed "medium" preset, which could land anywhere relative to your limit.
- My photo looks blocky when forced under 100 KB. Why?
- A multi-megapixel photo holds more detail than a 100 KB budget can store, so heavy compression shows JPEG blocking. Resize it first, for example to 1600 px wide with the Image Resize tool, then compress; you'll hit the same target with a far cleaner picture.
- Does compressing also change the pixel dimensions?
- No. It only lowers file size by re-encoding; the width and height stay exactly the same. Pixel dimensions and file size are separate things, so resize separately if you also need smaller dimensions.
- Is there a maximum file size it can handle?
- There's no server limit because every attempt is encoded locally in your browser, so the practical ceiling is your device's memory. Large photos straight from a phone work fine, and the tool shows the original size, the new size, and the percent saved.
Privacy
The tool tries JPEG quality levels locally until it finds one under your target size — every attempt happens in your browser, with nothing sent to a server.