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Resize an image in cm and KB
Form instructions often give a size in centimetres and a limit in KB. Enter both, with the DPI, and get a JPG that matches on every count.
- Centimetres, inches or pixels
- DPI written into the file
- KB limits and ranges
Centimetres and inches use the DPI below, or 200 DPI if none is set, and that DPI is written into the JPG so it prints at this size.
Check my file
Drop the file you plan to upload to compare it with the limits above.
More sizes, ranges and DPI
How to resize image in cm and KB
Choose the image
A photo, signature or thumb impression. Crop it roughly first if there is a lot around it.
Enter the size in cm
3.5 x 4.5 cm is filled in. Tap another size, which also fills in the KB range the form in the table sets for it, or type your own in cm or inches.
Set the DPI and KB
200 DPI and 20 to 50 KB are set. The line under the size shows the pixels that makes.
Download and check
Check my file confirms the pixels, the DPI stored in the file and the KB.
How centimetres become pixels
A file on screen has no centimetres, only pixels. The DPI (dots per inch) links the two: pixels = cm ÷ 2.54 × DPI. At 200 DPI, 3.5 cm is 3.5 ÷ 2.54 × 200 = 276 pixels. These are the sizes forms we checked ask for:
| Size | At 200 DPI | At 300 DPI | Asked for by |
|---|---|---|---|
| 3.5 x 4.5 cm | 276 x 354 px | 413 x 531 px | Photo: SSC CHSL 2022, J&K BOPEE |
| 4 x 2 cm | 315 x 157 px | 472 x 236 px | Signature: SSC CHSL 2022 |
| 3.5 x 1.5 cm | 276 x 118 px | 413 x 177 px | Signature: J&K BOPEE |
| 3 x 3 cm | 236 x 236 px | 354 x 354 px | Thumb impression: Punjab & Sind Bank |
| 10 x 5 cm | 787 x 394 px | 1181 x 591 px | Declaration: Punjab & Sind Bank |
| 2 x 2 in | 400 x 400 px | 600 x 600 px | See the US passport photo page |
Forms round these numbers. Punjab & Sind Bank writes 240 x 240 pixels in 200 DPI for a 3 x 3 cm thumb impression, where the exact figure is 236. A few pixels either way make no visible difference, and if a form gives pixels, type those instead of centimetres.
When the cm size and the pixels disagree
The same bank notice asks for a 4.5 x 3.5 cm photo and 200 x 230 pixels. At 200 DPI, 3.5 x 4.5 cm would be 276 x 354 pixels, so the two do not match. An upload page measures pixels and bytes, and it can only see centimetres through the DPI stored in the file. So when both are given, use the pixel size. Centimetres matter when the photo is printed.
Worked example: an SSC-style photo and signature
The SSC CHSL 2022 notice asks for a photo of about 3.5 x 4.5 cm at 20 to 50 KB and a signature of about 4 x 2 cm at 10 to 20 KB. At 200 DPI, that is 276 x 354 pixels and 315 x 157 pixels.
In our tests the portrait came to 26.4 KB at quality 95 and the busy street photo to 49.1 KB at quality 93, both inside 20 to 50 KB. Our test signature at 315 x 157 came to 11.5 KB at quality 96, just over the 10 KB minimum: the tool raises the quality only as far as the minimum needs, and at quality 95 the same signature was 10.2 KB, which fails where a site counts 1,024 bytes to the kilobyte. So run it through Check my file before you upload.
Sources, checked 13 October 2026: Staff Selection Commission (KKR), CHSL 2022 notice on photographs and signatures (PDF); J&K BOPEE, guidelines for scanning photograph, signature and thumb impression; Punjab & Sind Bank, guidelines for scanning photograph, signature, thumb impression and declaration (2024, PDF); MSTC Limited, steps for uploading images and documents.
Questions
How do I resize a photo to 3.5 cm x 4.5 cm?
Keep the filled-in 3.5 x 4.5 cm, choose the DPI your form names (200 if it names none) and download. At 200 DPI the photo becomes 276 x 354 pixels; at 300 DPI, 413 x 531.
How do I resize an image in cm, KB and DPI at once?
Enter all three here: the size in cm under Exact size, the DPI in the DPI box and the KB limit at the top. The DPI sets the pixels and is also written into the JPG. With DPI left as Not set, centimetres use 200 DPI, and 200 is what the file stores.
What is the aspect ratio of 3.5 x 4.5 cm?
7:9, about 0.78. Any pixel size with that shape works; 413 x 531 is exactly 7:9 and 276 x 354 is within a pixel of it.
Should I use 200 or 300 DPI?
Use the DPI your form names. The Indian upload notices we checked, such as J&K BOPEE, MSTC and Punjab & Sind Bank, ask for scans at 200 DPI or more, so 200 is a safe default for them. 300 DPI suits printing.
Can I resize a photo in inches?
Yes. Switch the unit from cm to inches, or tap 2 x 2 in. The same rule applies: 2 inches at 300 DPI is 600 pixels.
Why does the tool say my file is below the minimum?
At a small size like 3.5 x 1.5 cm, a clean signature may not hold 10 KB even at full quality. Check whether your form allows a larger size or a higher DPI, either of which gives more pixels. To change only the stored DPI, use change image DPI.
Is my image uploaded?
No. The resizing happens in your browser, and your photo stays on your device.
Related tools
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