How to resize a photo to a size in cm
- Tap Choose image above and pick your photo (JPG, PNG, iPhone HEIC and more).
- On the Dimensions tab, type the Width and Height and pick the Unit (cm, mm or inch). The line below shows the pixel result.
- Pick the DPI: the one your form states, or 300 if it states none.
- Pick Aspect handling (see below), then tap Resize and Download result.
- If the form also has a KB limit, tap Keep editing this result first, then use Exact KB. The pixel size stays as you set it.
Without step 5, Exact KB starts again from your original photo and may change its pixel size to fit the limit.
How centimetres become pixels
Pixels = size in inches × DPI, and 1 inch = 2.54 cm = 25.4 mm. So 3.5 cm at 300 DPI is 3.5 ÷ 2.54 × 300 ≈ 413 pixels, and 4.5 cm is ≈ 531. The same 3.5 × 4.5 cm at 96 DPI is only 132 × 170 pixels. That's why the DPI matters: the wrong one gives a photo of the right shape but far too few pixels for the form.
| Size | 300 DPI | 200 DPI | 96 DPI | Used for |
|---|---|---|---|---|
| 3.5 × 4.5 cm | 413×531 px | 276×354 px | 132×170 px | PPSC photo (minimum) and other forms that state 3.5×4.5 cm |
| 35 × 45 mm | 413×531 px | 276×354 px | 132×170 px | The same size in mm; India passport (35×45 mm) |
| 2 × 2 inches | 600×600 px | 400×400 px | 192×192 px | US visa and passport |
| 6 × 2 cm | 709×236 px | 472×157 px | 227×76 px | SSC signature |
| 86 × 54 mm | 1016×638 px | 677×425 px | 325×204 px | ID card (CNIC), landscape |
Rounded to the nearest pixel, which is what the tool uses. The cm to pixels calculator converts any size.
Which DPI to choose
Use the DPI your form states. If it gives only a physical size, 300 DPI is the usual print resolution for photos and the safe choice: it gives enough pixels for a sharp print, and a portal that checks pixels gets a generous number. If the form gives pixels as well (for example "600 × 600 pixels"), the pixels are what's checked: switch the unit to pixels and type them.
The DPI is saved in the file
A JPEG can record its intended print resolution. PixKB writes the DPI you chose into the file, so a 413 × 531 photo made at 300 DPI shows as 3.5 × 4.5 cm in Word, print dialogs and any portal that reads the DPI, instead of the 11 × 14 cm or larger that a program may show when no DPI is recorded. We checked the saved value with an image library after each test below.
Crop, stretch or pad: tested
If your photo's shape differs from the target, Aspect handling decides what happens. Our test portrait (4160 × 6240, a 2:3 shape) resized to 3.5 × 4.5 cm at 300 DPI:
| Aspect handling | Result | What it does |
|---|---|---|
| Crop to fill exactly (recommended) | 413×531 px, 39 KB | Keeps proportions and trims the edges evenly. Best for portraits taken with room around the head. |
| Fit inside, pad white | 413×531 px, 36 KB | Keeps the whole photo and adds white bars where the shapes differ. Use it when a form forbids cropping. |
| Stretch to exact size | 413×531 px, 39 KB | Squeezes the photo to fit, distorting faces. Rarely the right choice. |
Desktop Chromium, October 2026, JPEG quality 92%. Each file recorded 300 DPI. Other sizes from the same photo: 2 × 2 inches → 600×600 px, 59 KB; 35 × 45 mm at 600 DPI → 827×1063 px, 126 KB; 3.5 × 4.5 cm at 96 DPI → 132×170 px, 7.5 KB.
Some forms don't allow cropped photos: PPSC and the Pakistan passport say you can't use photos "cut down from larger pictures", and UK and Canadian online photos must not be cropped. For those, use the form's preset, which follows that rule, or Fit inside, pad white.
Common mistakes
- Choosing 96 or 72 DPI for a form photo. These are screen values and give tiny images (132×170 for 3.5×4.5 cm).
- Resizing, then compressing the original by mistake. Tap Keep editing this result before using Exact KB.
- Width and height swapped. 3.5 × 4.5 cm is upright: width 3.5, height 4.5.
- Cropping a landscape photo into a portrait size. A wide photo loses most of its sides. Start from an upright photo.
- Enlarging a small photo. Making 300×400 pixels into 827×1063 adds no detail; it just looks soft. Use a larger original.
Frequently asked questions
How do I resize a photo to 3.5 × 4.5 cm?
This page opens set to 3.5 × 4.5 cm at 300 DPI. Choose your photo, keep Crop to fill exactly, tap Resize and download. You get 413 × 531 pixels, saved as 300 DPI.
Is 35 × 45 mm the same as 3.5 × 4.5 cm?
Yes. Same size, different units: both give 413 × 531 pixels at 300 DPI.
How many pixels is 2 × 2 inches?
600 × 600 at 300 DPI. The US visa photo also accepts up to 1200 × 1200.
What DPI should I choose?
The one your form states. If it gives only cm or inches, 300 DPI.
Will the photo print at the right size?
Yes, when printed at actual size (100%). The DPI is saved in the file, so 413 × 531 pixels at 300 DPI prints as 3.5 × 4.5 cm. Many print dialogs default to Fit to page, which enlarges it: switch that off.
Does resizing change the file size in KB?
Yes. Fewer pixels usually means fewer KB: our 26-megapixel photo became 39 KB at 3.5 × 4.5 cm. For a KB limit, tap Keep editing this result, then use Exact KB.
My form forbids cropping. What do I do?
Use the form's preset if there is one, or choose Fit inside, pad white: the whole photo is kept and white fills the gaps.
Is my photo uploaded?
No. It's resized in your browser and saved to your device.