How to Compress a Photo to 20 KB, 50 KB or 100 KB
A practical guide to shrinking a photo to an exact file size for online forms — without making it blurry, and without uploading it anywhere.
Many online applications — university admissions, job portals, exam registrations, visa and ID services — refuse photos that are larger than a fixed limit such as 20 KB, 50 KB or 100 KB. A photo straight from a phone camera is usually 2–6 MB, which is 40 to 300 times too big. This guide explains what actually controls file size and how to hit a limit while keeping the photo as sharp as possible.
What decides the size of a photo file
Three things determine how many kilobytes a photo takes: its dimensions (how many pixels wide and high it is), its format (JPG, PNG or WebP) and, for JPG and WebP, its compression quality. A 4000 × 3000 photo has 12 million pixels; a 600 × 800 passport-style photo has fewer than half a million. Fewer pixels means less data to store, so reducing dimensions is the single most powerful way to make a file smaller.
Compression quality is the second lever. JPG and WebP throw away detail the eye is unlikely to notice. At high quality (around 90%) the loss is invisible; at medium quality (70–80%) it is very hard to see on a normal screen; below about 60% you start to see blocky patches, smeared edges and "halos" around text and hair.
The right order: quality first, then dimensions
The common mistake is to drag a quality slider all the way down until the file fits. That produces a small file that looks terrible. A better approach is to keep quality in the comfortable range and reduce dimensions only as much as needed. PhotoSize does this automatically: it searches for the highest quality that fits your target, and if even good quality is too big it reduces the dimensions step by step, then works back up to the largest size that still fits.
| Target size | Typical result for a normal photo | Good for |
|---|---|---|
| 20 KB | About 400–600 px wide, quality ~70–80% | Exam and recruitment forms with strict limits |
| 50 KB | About 700–1000 px wide, quality ~75–85% | Most application portals |
| 100 KB | About 1000–1400 px wide, quality ~80–90% | ID uploads, profile photos |
| 200 KB+ | Often full size or close to it | Documents that need fine detail |
Tip: If the form also specifies exact dimensions (for example 200 × 230 pixels), set those first. At small dimensions even 20 KB is usually enough for excellent quality.
Step by step
- Open the Compress to KB tool and select your photo (or up to five photos at once).
- Choose a target such as 20 KB, 50 KB or 100 KB, or type a custom value.
- Keep the output format as JPG unless the form asks for something else — JPG gives the smallest files for photographs.
- Leave "Reduce dimensions if needed" switched on so very small targets can be reached without ugly compression.
- Press Compress. The result screen shows the final size, the dimensions and a green check when the file meets your limit.
- Save the photo and upload it to the form.
When a target cannot be reached
Some combinations are physically impossible: a 2000 × 2000 pixel photo will never fit in 5 KB at any usable quality. If you have fixed dimensions and a tiny size limit, PhotoSize tells you the smallest size it could achieve and suggests what to change — usually allowing smaller dimensions, raising the limit slightly, or switching from PNG to JPG.
Privacy
Many "online compressors" upload your photo to a server. PhotoSize processes everything inside your browser, on your own device. Your photo is never sent anywhere, which matters for identity documents and signatures.