Compress images to an exact KB size
Form says “20–50 KB only”? Set the target, drop the photo, download a file that fits — without uploading it anywhere. Free, no signup, works offline.
Drop images here — or click to browse, or paste with Ctrl+V
JPG · PNG · WebP — processed on your device, never uploaded
How it works
- Set your target size in KB — type it or tap a preset chip.
- Drop images in, click to browse, or paste with Ctrl+V. Batches welcome.
- Your browser re-encodes each image on your device until it fits the target.
- Preview the result, check the exact size, download. Done.
Under the hood, the tool runs a binary search on the encoder’s quality setting — encode, measure, adjust, about seven rounds — and keeps the highest quality that fits your byte target. If no quality level fits, it steps the pixel dimensions down and tries again. The whole search happens in milliseconds because it never waits on a network. Read the full explanation.
Built for forms with hard limits
Most image compressors make files “smaller”. Upload forms don’t want smaller — they want under 50 KB, or between 10 and 20 KB, or exactly 630 × 810 pixels under 250 KB. Government portals, exam applications, job boards and visa systems reject anything else, some after a limited number of attempts. ShrinkToKB targets the byte limit and the pixel dimensions directly, so the file you download is the file that passes.
Why local-only matters for these photos
Think about what you compress for a form: your face, your signature, scans of identity documents. A conventional “free online compressor” uploads those to a server you know nothing about, with a privacy policy you’ll never read. ShrinkToKB was built so that question never comes up — the site is static, there is no upload endpoint, and the tool keeps working with your Wi-Fi switched off. Here’s how to verify that yourself — on this site or any other.
Frequently asked questions
How is this different from other image compressors?
Two ways. First, you set an exact size target in KB — the tool binary-searches the encoder settings to land just under it, instead of giving you a random “smaller” file. Second, it runs entirely in your browser: your images are never uploaded, which you can verify in DevTools or by using it offline.
Is it really free? What’s the catch?
It’s free — no account, no email, no watermark, no daily cap. Because your own device does the work, running the site costs almost nothing. If the site ever carries ads, they’ll sit outside the tool and will never see your files: the no-upload architecture doesn’t change.
Which formats can I compress?
Input: JPG, PNG, WebP and anything else your browser can decode (AVIF in most browsers). Output: JPG (best for photos and forms), WebP (smallest for web use) or PNG (lossless, fitted by resizing). HEIC from iPhones needs converting to JPG first — most browsers can’t decode it.
Why do government forms demand sizes like 20 KB or 50 KB?
Legacy infrastructure and fairness: portals serving millions of applicants cap file sizes to keep storage and review manageable. The caps are strict — a byte over and the upload fails — which is exactly why this tool targets the limit precisely instead of approximately.
Does compressing remove hidden data from my photos?
Yes. The output is drawn onto a fresh canvas and re-encoded, so EXIF metadata — GPS location, camera model, timestamps — doesn’t carry over. For photos of your face or documents, that’s a privacy bonus on top of the no-upload design.
Can I use it on my phone?
Yes — everything works in mobile browsers, including camera-roll uploads. You can also install the site as an app (Add to Home Screen); it keeps working with no connection at all.