Pixels, KB and DPI: Upload Sizes Explained
Understand pixels, KB and DPI with worked upload examples. Learn which controls change dimensions, file size and resolution metadata for forms.
By Rai Ansar · Reviewed
This is technical preparation guidance, not an application authority’s approval. Your current official notice and upload screen take precedence. Numerical examples below are illustrative, not universal requirements.
The short answer
Pixels describe the image’s width and height. KB describes how much storage the encoded file occupies. DPI describes a resolution value associated with physical size. They are different checks: a small file can have the wrong dimensions, and an image with the right dimensions can still exceed the upload limit.
- Pixel dimensions
- A 200 × 230 image is 200 pixels wide and 230 pixels high. Reversing those numbers creates a different shape. Resizing changes this pixel grid; cropping changes which part of the source appears in it.
- File size
- The stored bytes depend on the format, image detail, compression and metadata. There is no fixed conversion from 200 × 230 pixels to a particular number of KB.
- DPI or resolution metadata
- A density value can associate pixels with a physical length. Changing the density field alone does not add detail to a blurry picture or change its pixel dimensions.
A worked example: why one passing check is not enough
Suppose an upload screen asks for a JPG, 200 × 230 pixels, between 20 and 50 KB. Those are four requirements: format, width and height, lower size bound, and upper size bound.
- A 200 × 230 JPG of 55 KB is too large, despite having the right dimensions.
- A 200 × 230 JPG of 12 KB is below the example’s minimum. Making it even smaller would move in the wrong direction.
- A 230 × 200 JPG of 35 KB has the width and height reversed.
- A 200 × 230 JPG of 35 KB meets these example numerical checks, but may still fail rules about the face, background, age of the photograph or other content.
Use the numbers shown by your own portal. This example is not a recommendation to resize every application photograph to 200 × 230.
For a sourced example, see IBPS declaration: pixels, DPI and file size in the archived Office Assistant requirements. Check the current notice before using those specifications for another application.
What “50 KB” means in FormAssets
Portals disagree on whether 1 KB is 1,000 or 1,024 bytes. The photo resizer keeps a file at or under the maximum × 1,000 bytes and at or over the minimum × 1,024 bytes, so it passes under either count: a 50 KB maximum means at most 50,000 bytes. Its result shows the size both ways.
A rounded size display cannot prove that a file is under a boundary. If the portal states a limit in bytes, compare bytes directly.
When physical dimensions and DPI matter
For a hypothetical instruction of 2 inches wide at 200 pixels per inch, the corresponding width is 2 × 200 = 400 pixels. If centimetres are specified, divide centimetres by 2.54 before multiplying by the density. This arithmetic does not tell you which values a portal accepts: an instruction that separately specifies pixels must also be followed.
The photo resizer can write a DPI value into the JPG: type it in the DPI box when you enter exact pixels, or enter a size in centimetres with a DPI. The value is a label in the file and adds no pixels, so match the pixel size the notice states as well. Without a DPI setting, a browser's canvas export carries 96-DPI resolution metadata where the format supports it; see MDN’s canvas export documentation.
Measured examples: pixels, quality and KB
Pixels alone cannot predict a file size. Each row saves the same computer-generated test photo or drawn test signature at fixed pixels, changing only the JPG quality.
| Sample | Pixels | Quality | JPEG size |
|---|---|---|---|
| Test photo | 600 × 450 px | 40 / 100 | 16.2 KB |
| Test photo | 600 × 450 px | 60 / 100 | 23.9 KB |
| Test photo | 600 × 450 px | 80 / 100 | 41.4 KB |
| Test photo | 600 × 450 px | 100 / 100 | 221.9 KB |
| Test signature | 472 × 157 px | 40 / 100 | 3.4 KB |
| Test signature | 472 × 157 px | 60 / 100 | 4.5 KB |
| Test signature | 472 × 157 px | 80 / 100 | 7.4 KB |
| Test signature | 472 × 157 px | 100 / 100 | 35.0 KB |
Tested on 11 October 2026 by running FormAssets' own code outside the browser. A KB in this table is 1,000 bytes. A browser's JPG encoder can give different sizes, so treat the table as an example.
Convert a physical size to pixels
Enter a length in centimetres, millimetres or inches and a DPI (dots per inch), and this works out the pixel size: pixels = size in inches × DPI. It does not read or resize an image; use the photo resizer for that once you have the pixel number.
2 in at 300 DPI is 600 px.
Example: a 2 in (2 × 2 in US passport photo) side at 300 DPI is 600 px, the size the U.S. Department of State's visa photo page asks Diversity Visa entrants for. A 45 mm side at 300 DPI is about 531 px; GOV.UK instead states a direct pixel minimum for its online upload (600 × 750 px) rather than a DPI conversion. See the passport and visa sizes.
Convert MB to KB (or KB to MB)
Enter a value in either field. 1 MB = 1,024 KB, the same base this site uses for the KB shown by the photo resizer.
2 MB is 2048 KB.
A file reported as "2 MB" is about 2,048 KB. If your notice sets a maximum in KB, use that number directly in the photo resizer's maximum file size field; this converter does not read or resize a file.
Choose the control for the actual problem
- Open the photo resizer. Pick your notice's preset if it is listed; otherwise enter the minimum and maximum KB, choose “Exact pixels from my form” and type the width and height in the order the notice gives.
- Choose “Fill frame, crop edges” only when the crop keeps all required content. Choose “Fit all, add white space” when preserving the whole image is more important and the receiving rules allow the resulting margins.
- Choose your image and select “Make JPG”. The tool keeps the file inside the range you set; it does not promise an exact KB value.
- Download and open the JPG. Inspect legibility as well as the reported dimensions and size. The tool checks only the numbers you enter, not a portal's other rules.
For a supported application with a minimum size or DPI rule, inspect its source-linked preset and current official instructions instead. A numerical pass is preparation evidence, not a submission receipt.