At 20KB, resize first
Compression alone will not save a full-resolution photo at 20KB; you will get visible blocking and colour banding. The fix is to cut the pixel count hard before compressing.
Practical starting points: for a face photo, try 300×400 pixels. For a scanned signature, 300×80 is usually plenty and often what the portal expects. Once the dimensions are modest, 20KB is a comfortable budget rather than a punishing one.
Signatures and scanned documents
Signature uploads are the most common reason to need 20KB, and they behave differently from photos. A signature is mostly white with thin dark strokes, which JPEG handles badly — it produces grey haloes around the ink.
If the portal accepts PNG for signatures, use it: a 300×80 black-and-white signature as PNG will often come in under 10KB and stay perfectly crisp. Only fall back to JPEG if the form demands it.
Frequently asked questions
- My 20KB photo looks blocky. What do I do?
- Reduce the pixel dimensions and re-run. Blockiness at a fixed byte limit is a symptom of too many pixels sharing too few bytes, so fewer pixels is the direct cure.
- Is 20KB enough for a passport photo upload?
- It can be, at around 300×400 pixels. Check whether the portal also specifies minimum dimensions — some require 600×800 while still capping the file at 20KB, which forces lower quality.
- Should I use PNG or JPEG at 20KB?
- JPEG for photographs. PNG for signatures, line art and anything with flat colour and sharp edges, where it is both smaller and cleaner at this size.