Image Resizer: Resize Photo in Pixels, cm, mm or KB

How to resize an image

Use this free image resizer to change a photo to exact pixels, centimetres, millimetres or inches, and optionally keep it under a file size in KB. It works offline in your browser once the page has loaded.

1. Click Click to Upload or Drag & Drop Image and pick a JPG, PNG or WebP file. Its pixel size and KB size are shown.
2. Pick Dimensions or Percentage. For forms that give a size in cm or mm, choose that unit and set the DPI (300 if the form does not say).
3. Type the width. With Lock aspect ratio on, the height follows automatically so the face is not stretched. Turn the lock off only if the form needs an exact width and height.
4. Choose JPEG for exam portals and, if there is a KB limit, enter it in Max file size in KB.
5. Click Resize Image, check the size shown on the button, and download.

How pixels, cm and DPI are related

A digital image only has pixels. A size in cm or mm becomes pixels once you choose a DPI (dots per inch). One inch is 2.54 cm or 25.4 mm, so:

pixels = (cm ÷ 2.54) × DPI  or  pixels = (mm ÷ 25.4) × DPI

Worked example: an Indian passport-size photo of 35 × 45 mm at 300 DPI is (35 ÷ 25.4) × 300 = 413.4, so 413 px wide, and (45 ÷ 25.4) × 300 = 531.5, so 531 px tall. A signature box of 6.0 × 2.0 cm at 100 DPI is 236 × 79 px.

File size in KB is a separate thing from pixel size. It depends on the pixel count, the format and the JPEG quality. Halving the width and height leaves a quarter of the pixels, which usually cuts a JPEG to roughly a quarter of its size. That is why a photo that will not go under the limit by quality alone should also be made smaller.

Exam form photo and signature sizes

Rules change from one notification to the next. The table lists what the official sources said when this page was updated; always check your notification before uploading.

• Tip: scan the signature in black ink on plain white paper, crop close to the ink, then resize. A tiny signature on a large white page looks blurred after compression.
• Common mistake: stretching a photo to a square or a fixed size with the aspect lock off. Crop first, then resize with the lock on.

Frequently Asked Questions

How do I resize a photo to a specific size in cm or mm?

Choose cm or mm in the Unit box, set the DPI (300 is the usual print value), and type the width and height. The tool converts them to pixels with pixels = cm / 2.54 x DPI, so 3.5 x 4.5 cm at 300 DPI becomes 413 x 531 px.

How do I reduce a photo to under 200 KB or 100 KB?

Choose JPEG, then type the limit in Max file size in KB and click Resize Image. The tool lowers the quality step by step until the file fits; if it still does not fit at the lowest quality, reduce the width and height as well.

What photo and signature size does UPSC ask for?

UPSC's current upload instructions ask for a JPG photo of 20 KB to 200 KB and a JPG signature file of 20 KB to 100 KB that is 350 to 500 pixels, with your signature written three times one below the other. Check the instructions on upsconline.nic.in for your exam before uploading, because they change.

What signature size does SSC ask for?

The SSC CGL 2026 notice asks for a scanned signature in JPEG of 10 KB to 20 KB, about 6.0 cm wide and 2.0 cm high; the photo is captured live inside the application form. Other SSC exams publish their own notices, so check your notification.

Will resizing reduce image quality?

Making an image smaller keeps it sharp because the tool uses high-quality resampling from the pica library. Making it larger cannot add detail, so enlarged photos look soft; start from the biggest original you have.

Is my photo uploaded to a server?

No. The photo is resized inside your browser and never leaves your device, which matters for ID photos and signatures.