How do I reduce a photo to 20 KB for a form without making it blurry?

A form asks for a photo of "not more than 20 KB". The photo on your phone is 3 MB. You try a website, type 20 KB, and get back one of two things: a blocky, smeared face, or a file that is still too big with a cheerful "done" message next to it.

Neither is your fault, and your photo is fine. The problem is the order in which the work is done.

What 20 KB actually is

20 KB is 20,000 bytes. (Some portals count 20,480; KB vs KiB explains why that matters.) A JPG photo spends its bytes on two things:

• Pixels: how many dots make up the picture. A phone photo has millions of them.
• Quality: how much detail is kept in each small patch of the picture. Low quality shows up as blocks, smudges and halos around edges.

The file grows with both. Double the width and the height and you have four times as many pixels to pay for. Lower the quality and each patch costs less, until the face starts to break up.

Why full size can never fit

We made a test photo of 2000 × 2600 pixels, about 1.6 MB, and saved it at every JPG quality from best to worst. At the very lowest quality, where the picture is barely recognisable, it was still 32 KB. Many phone cameras take photos with more pixels than that.

So a tool that keeps every pixel and only turns down the quality has two choices: go over your limit, or ruin the picture. We saw both when we tested resizers. One returned 31 KB for a 20 KB target and still showed a success message. Another went the other way and returned about 7 KB, barely a third of what was allowed, which throws away detail you were entitled to keep.

Pixels first, then quality

A clear 20 KB photo comes from cutting the pixels to a sensible size first, then spending what is left of the 20 KB on quality. This is what our test photo became when we worked that way:

661 × 859 pixels is a lot for a form. For comparison, the bank-exam photo in the SBI scanning guidelines is 200 × 230 pixels.

Your own numbers will differ a little. Every browser saves JPG slightly differently, and a plain wall behind you costs fewer bytes than a busy street. The pattern holds.

Is 20 KB your maximum or your minimum?

Read the notice twice. 20 KB is often a floor, not a ceiling.

When the form fixes the pixels as well, as the bank exams do, there is no trade-off to make. The tool resizes to exactly those pixels and uses the highest quality that fits. The full set of bank-exam files is in IBPS and SBI photo, signature, thumb and declaration sizes.

Step by step

1. Open Resize Image to 20 KB, which is Resize Image with 20 already typed in the File size box. If your form also gives a pixel size, type it in Width and Height (in px, cm, mm or inches); if it gives a minimum, open More options and type it in Smallest size.
2. Add your photo. It is worked on in your browser and never uploaded. An iPhone photo in HEIC opens directly in Safari on the iPhone.
3. Wait a moment while the preview finds the size. It updates as you change anything.
4. Read the preview and the checks: size in KB and in exact bytes, pixels, JPG, file name. Then tap Actual size and look at the eyes and the edge of the hair, where blur shows first.
5. If the face looks soft and you did not type a pixel size, open More options and move Sharper or larger towards Sharper: fewer pixels, cleaner detail. Then tap Resize picture and download.

Why a 20 KB photo still gets rejected

• Over by a few hundred bytes. A file your computer calls 19.9 KB can be 20,400 bytes, which a portal counting in thousands reads as 20.4 KB.
• Under a minimum. "20 to 50 KB" means a 15 KB photo fails too.
• Right KB, wrong pixels. A photo can meet the size and still not be 200 × 230 or whatever the form asks for.
• Not a JPG. PNG, HEIC and WebP are often refused where the form says JPG only. For a form, the tool saves JPG.
• Sideways. See why photos upload sideways.
• The photo itself. Some portals check the face or the background. A resizer cannot change what the portal thinks of the photo.

What the tool cannot do

It cannot add detail that was never there: a shaky or out-of-focus photo stays soft at any size. It cannot make a limit and a pixel size fit together when they do not; it tells you the smallest size it reached and what you could change, and it will not download a file that breaks the limit. And it cannot check your form's rules on face, background or clothing. Those are in your notice.