Photos for forms
Why is my '20 KB' file still rejected? KB vs KiB explained
Some systems count a kilobyte as 1,000 bytes and others as 1,024, so the same file can be 19.9 KB on your computer and 20.4 KB to the portal. Go by the exact byte count: for a 10 to 20 KB rule, a file of 10,240 to 20,000 bytes passes both ways of counting. Resize Image aims inside that range and shows the exact bytes.
Your computer says the photo is 19.9 KB. The form says it is over 20 KB. Or the other way round: your signature shows 10.1 KB, and the portal says it is under the 10 KB minimum.
Both of you are right. You are counting in different kilobytes.
Two kinds of kilobyte
- kB, 1,000 bytes. The metric kilobyte, like a kilogram is 1,000 grams.
- KiB, 1,024 bytes. The "kibibyte". Computers work in powers of two, and 1,024 is the one closest to a thousand.
Most people, and most forms, write "KB" for both. Windows File Explorer counts 1,024 bytes to a KB. A Mac counts 1,000. A form notice writes "20 KB" without saying which it means, and the portal behind it could count either way.
The same file, read two ways
| Exact size | Counted in 1,000s | Counted in 1,024s | Passes "at most 20 KB"? |
|---|---|---|---|
| 19,900 bytes | 19.90 KB | 19.43 KB | Yes, both ways |
| 20,400 bytes | 20.40 KB | 19.92 KB | Only if the portal counts in 1,024s |
| 20,725 bytes | 20.73 KB | 20.24 KB | No, either way |
| Exact size | Counted in 1,000s | Counted in 1,024s | Passes "at least 10 KB"? |
|---|---|---|---|
| 10,100 bytes | 10.10 KB | 9.86 KB | Only if the portal counts in 1,000s |
| 10,240 bytes | 10.24 KB | 10.00 KB | Yes, both ways |
A gap of 2.4% sounds like nothing. On a 20 KB limit it is 480 bytes, and a file can easily land in that gap.
The range that passes both
For a maximum, the stricter reading is 1,000 bytes per KB. For a minimum, the stricter reading is 1,024. Put them together and you get a range that passes whichever way the portal counts:
at least (minimum × 1,024) bytes, and at most (maximum × 1,000) bytes.
| Rule in the notice | Safe range in bytes | Where the rule comes from | How sure we are |
|---|---|---|---|
| Signature, 10 to 20 KB | 10,240 to 20,000 | SBI guidelines for scanning and uploading documents (checked September 2026) | Read in the official document |
| Photo or thumb impression, 20 to 50 KB | 20,480 to 50,000 | The same guidelines | Read in the official document |
| Handwritten declaration, 50 to 100 KB | 51,200 to 100,000 | The same guidelines | Read in the official document |
| Bangladesh government job photo, up to 100 KB | up to 100,000 | NTRCA online application help page | Read on the official page |
| Bangladesh government job signature, up to 60 KB | up to 60,000 | The same page | Read on the official page |
Resize Image always aims inside this range, and checks the real file that you will download, not an estimate.
How to see the exact bytes
- Windows: right-click the file and choose Properties. The size is shown in KB with the exact bytes in brackets.
- Mac: select the file and choose Get Info. The size in bytes is shown next to the rounded one.
- In Resize Image: the preview shows the KB and the exact bytes together, with the pixels beside them, for example 19,900 bytes at 661 × 859 pixels.
Resize Image shows KB in 1,024s, the way Windows does, so it matches what you see on your computer. That is why a 20 KB result never shows more than about 19.5 KB: 20,000 bytes is 19.53 KB when counted in 1,024s. It is not a mistake; it is the safe side.
Step by step
- Open Resize Image. Type the maximum in the File size box exactly as the notice writes it. If there is a minimum, open More options and type it in Smallest size.
- Add your photo or signature.
- Read the preview: KB, exact bytes and pixels, with a check for the KB range.
- Tap Resize picture, download, and upload that file directly. Do not open and save it again in another app, and do not send it through a chat app first; either can change the size.
Why a "right size" file still gets rejected
- A few hundred bytes over, when the portal counts in 1,000s.
- Just under a minimum, when the portal counts in 1,024s.
- A rounded number in a file list. File lists round, so a file shown as "20 KB" can be a little under or a little over.
- The file changed after you checked it, because it was edited, re-saved or passed through a chat app.
- The size was fine but something else was not: pixels, JPG, or a sideways photo. See why photos upload sideways.
What the tool cannot do
It cannot find out which way a particular portal counts. It does not need to: a file in the safe range passes both. If the notice gives a limit in MB, remember that 1 MB can mean 1,000,000 or 1,048,576 bytes; typing the limit as 1000 KB keeps you on the safe side.
Common questions
Is 1 KB 1,000 bytes or 1,024 bytes?
Both are in use. Strictly, kB is 1,000 bytes and KiB is 1,024, but most people and most forms write KB for either. Windows counts 1,024 bytes to a KB, and a Mac counts 1,000.
Why does Resize Image show 19.5 KB when I asked for 20 KB?
It shows KB in 1,024s, as Windows does. The file is at most 20,000 bytes, so it passes a portal that counts in 1,000s, and 20,000 bytes is 19.53 KB when counted in 1,024s.
20kb फोटो फिर भी रिजेक्ट क्यों होती है?
Usually because your phone or computer counts 1,024 bytes to a KB and the portal counts 1,000, so the photo is a few hundred bytes over. In Bangla the same doubt is often searched as কেবি ১০০০ না ১০২৪. Check the exact bytes: for a 20 KB limit, stay at or under 20,000 bytes.
What does 10 to 20 KB mean in bytes?
To pass however the portal counts, at least 10,240 bytes and at most 20,000 bytes.