Photo size in KB vs pixels vs cm: the confusion that rejects forms
"3.5×4.5 cm, 200×230 px, 20–50 KB." What each number means, how they relate, and how to read any exam notice correctly the first time.
Three numbers, three meanings
- KB (kilobytes) is the file size: how much storage the JPEG takes.
- Pixels are the width and height of the image, for example 200×230.
- Centimetres describe a printed size, such as a 3.5×4.5 cm passport photo.
From cm to pixels
The bridge is DPI (dots per inch). One inch is 2.54 cm, so:
pixels = cm ÷ 2.54 × DPI
A 3.5 cm width at 300 DPI is 3.5 ÷ 2.54 × 300 ≈ 413 pixels. That is why ExamPhoto's NEET and JEE Main photo crop is 413×531. PAN scan guidance uses 200 DPI, which gives about 197×276 px for the photo.
Where KB comes from
File size depends on the number of pixels and on JPEG compression quality. Cut the pixels and the KB falls fast. This is why resizing before compressing gives sharper results.
How to read any notice in 30 seconds
- Find the pixel size. If it is printed, match it exactly.
- If only cm is printed, look for a DPI; otherwise a passport-style working crop is usually fine.
- Find the KB range and stay inside it, not at the edge.
- Note the format, usually JPG or JPEG.
When the notice gives a range
GATE 2027 allows a photo from 200×260 up to 530×690 px and 5–600 KB. Any size in the range passes the pixel check, but the face and background still need to match the official examples. See GATE photo visual rules.
For a form not listed on ExamPhoto, enter the numbers in the custom image resizer.
Prepare your file now
Free, no sign-up, and your image stays in your browser.
Frequently asked questions
How many pixels is 3.5×4.5 cm?
It depends on DPI. At 300 DPI it is about 413×531 pixels, which is the working crop ExamPhoto uses for NTA-style photos.
Does a higher KB mean a better photo?
Not always. KB depends on pixel size and compression. A sharp 200×230 px photo can be only 30 KB, while a blurry large photo can be several MB.
What does DPI mean in an exam notice?
Dots per inch. It links a print size in cm to a digital size in pixels. Some notices, such as PAN scan guidance, specify a DPI along with the cm size.
ExamPhoto is not affiliated with NTA, UPSC, SSC, IBPS, SBI, RRB or any exam authority. Sizes on this page match ExamPhoto's presets as of 5 November 2026. Always confirm the current official notice before you upload.