Passport Size Photo in Pixels: 3.5 × 4.5 cm at 200 and 300 DPI

A 3.5 × 4.5 cm passport size photo is 276 × 354 pixels at 200 DPI and 413 × 531 pixels at 300 DPI. Those are correct conversions, but they are the right upload size only when a form gives you centimetres and a DPI and nothing else. Many forms state their own pixel dimensions, and when they do, those pixels win.

This guide gives you the conversion table and the formula behind it, explains what DPI changes and what it does not, and shows how to produce an exact pixel size without squeezing a face out of shape.

Passport size photo in pixels at common DPI values

In India, the UK and many other countries, a passport-size print is 35 mm wide and 45 mm high, usually written as 3.5 × 4.5 cm. Indian notices sometimes put the height first: the 2026 SBI PO scanning guide lists the photograph as 4.5 cm × 3.5 cm. GOV.UK describes its printed photo as 45 mm high by 35 mm wide. It is the same rectangle either way, taller than it is wide.

Converted to pixels, that rectangle becomes:

DPI	Width × height in pixels	Total pixels
100	138 × 177	24,426
150	207 × 266	55,062
200	276 × 354	97,704
300	413 × 531	219,303
600	827 × 1063	879,101

Doubling the DPI doubles both sides, so the total number of pixels roughly quadruples. A 300 DPI version carries about 2.2 times the pixels of a 200 DPI one. More pixels can hold more detail, but they also need more bytes, which matters when the same form caps the file at 50 kB.

The formula, and how to round it

An inch is defined as exactly 25.4 mm, a definition NIST traces back to 1959. Pixels per inch multiplied by inches gives pixels, so:

pixels = millimetres ÷ 25.4 × DPI (or centimetres ÷ 2.54 × DPI)

Worked through for a 35 × 45 mm photo:

• Width at 300 DPI: 35 ÷ 25.4 × 300 = 413.39, which rounds to 413
• Height at 300 DPI: 45 ÷ 25.4 × 300 = 531.496, which rounds to 531
• Width at 200 DPI: 35 ÷ 25.4 × 200 = 275.59, which rounds to 276
• Height at 200 DPI: 45 ÷ 25.4 × 200 = 354.33, which rounds to 354

Round to the nearest whole pixel, because an image cannot contain part of one. Some calculators round 531.496 up to 532 or cut 275.59 down to 275. A one-pixel difference is invisible in the picture; it matters only when a form checks dimensions exactly, and in that case you should copy the form’s numbers rather than your own conversion.

The same formula works for any printed size an application mentions:

Printed size	At 200 DPI	At 300 DPI
35 × 45 mm (3.5 × 4.5 cm)	276 × 354	413 × 531
2 × 2 inch (50.8 mm square)	400 × 400	600 × 600
3 × 3 cm	236 × 236	354 × 354
6 × 2 cm	472 × 157	709 × 236
10 × 5 cm	787 × 394	1181 × 591

For sizes given in inches, skip the 25.4: a 2-inch side at 300 DPI is simply 2 × 300 = 600 pixels.

When the form lists pixels, use its pixels

The SBI PO 2026 scanning guide is a useful example of why conversions are not always the answer. It labels the photograph 4.5 cm × 3.5 cm, then asks for 200 × 230 pixels (preferred) with a file size of 20–50 kB. That pixel size is not a conversion of 3.5 × 4.5 cm: at 200 DPI the print size would be 276 × 354. It is even a different shape. 200 ÷ 230 is about 0.87, while 35 ÷ 45 is about 0.78.

The same guide shows that issuers round to tidy numbers. It gives the left-thumb impression as 240 × 240 pixels at 200 DPI and describes that as 3 cm × 3 cm, although the exact conversion is 236 × 236. The handwritten declaration is 800 × 400 pixels at 200 DPI for 10 cm × 5 cm, compared with an exact 787 × 394. The pixel figure is what an upload system can actually measure, so treat it as the requirement and the centimetres as a description.

Use this order when you read an instruction:

1. The form states pixels (exact, preferred, or a minimum and maximum). Use those pixels and ignore any conversion.
2. The form states centimetres and a DPI. Convert with the formula above.
3. The form states centimetres only. Treat the size as the required shape. Start at 413 × 531 for 3.5 × 4.5 cm; if the kB limit forces visibly poor quality, drop to 276 × 354, which keeps nearly the same shape.
4. The form states only a file size. Crop to the shape you need, keep the camera’s pixels unless the file is far too large, and let the kB target do the rest.

Passport applications usually fall under rule 1. The ICAO photo guidelines published by Indian missions abroad ask for a colour photograph of 630 × 810 pixels with a white background, where the face takes up 80–85% of the frame. That is exactly the 7:9 shape of a 35 × 45 mm print, yet it corresponds to about 457 DPI, which is not a standard setting anyone would pick. It is a pixel requirement, not a DPI one. For online UK passport applications, GOV.UK asks for a digital photo at least 600 pixels wide and 750 pixels tall, between 50 kB and 10 MB.

Both of those passport guidelines also say the photo must be unaltered by computer software. Resizing advice here is about meeting pixel and kB limits; it does not override an authority’s rules on editing, retouching, filters or background changes. Follow the capture method the passport service recommends whenever it gives one.

DPI is a print label, not extra detail

A digital photo is a fixed grid of pixels. DPI (for images, more precisely pixels per inch) is a number stored alongside that grid to tell printing software how large to print it. Change the number and the grid stays the same.

Take a 413 × 531 photo. Labelled 300 DPI, it prints at 3.5 × 4.5 cm. Labelled 72 DPI, the same pixels would print at about 14.6 × 18.7 cm. On screen and in an upload form, both versions look identical and contain identical detail. The label takes only a few bytes, so changing it does not move the file size in any meaningful way.

Some editors link the DPI field to the pixel dimensions. When their resampling option is switched on, raising the DPI makes the editor invent extra pixels. The file becomes larger, but no real detail is added, so an enlarged small photo still looks soft.

Browser-made images can surprise people here as well. MDN notes that canvas exports carry 96 DPI in formats that support resolution metadata. In a test for this guide in Chrome 150 (October 2026), JPEGs exported from a canvas, the method Mb2KbSizer uses, carried no DPI value at all: their JFIF headers had density units set to “none”. Any DPI a properties window shows for such a file is that program’s own default, not a value stored in the file. For a form that checks pixels and kB, this does not matter. If a service says its upload checks the DPI value itself, set it in an image editor with resampling turned off after you have the final pixel size.

Crop to the shape before you resize

The 3.5 × 4.5 cm shape is a 7:9 ratio. 413 × 531 and 630 × 810 match it exactly, while 276 × 354 is within a fraction of a percent. Phone cameras commonly produce 3:4 pictures, or 9:16 in widescreen modes, so a photo has to be cropped before it can become 7:9 without distortion.

Typing a width and height into a basic editor that does not keep proportions stretches the picture to fit. A 9:16 phone portrait forced into 7:9 would be widened by roughly 38%, which makes a face noticeably broad. Forms that check faces, and people who check them, can reject such a photo even though its numbers are correct.

Mb2KbSizer’s Exact width × height (crops edges) setting avoids stretching: it trims an equal amount from both sides, or from the top and bottom, until the picture matches the target shape, then scales it. Because the trim is centred, the result depends on where your face sits in the original. For a passport-style photo, where the head and shoulders must fill most of the frame, crop it yourself first in your phone or computer’s editor, roughly to the final shape and with the face centred. The dimensions versus file size guide explains when to use fit instead of exact sizing.

Make an exact-pixel photo with Mb2KbSizer

1. Start with the original camera photo, not a screenshot or a copy forwarded through a messaging app, which may already have lost detail.
2. Crop to head and shoulders with the face centred, close to the shape you need.
3. Open the image compressor and, before choosing the photo, open Format & dimensions. Set Output format to JPG / JPEG if the form asks for JPG, choose Exact width × height (crops edges), and enter the width and height in pixels, for example 413 and 531 or the numbers on the form.
4. Enter a Target file size inside the form’s range. For a 20–50 kB field, 45 kB leaves a small safety margin below the maximum.
5. Choose the photo. Compression starts straight away with these settings; if you change a setting afterwards, select Compress again with these settings.
6. Check the Dimensions result. In exact mode the tool keeps your width and height and adjusts only the JPEG quality to reach the target.
7. Zoom in on the eyes and hairline. If they look blocky, the kB limit is tight for that many pixels. Use a higher target within the permitted range, or, if the form allows it, a smaller size with the same shape.
8. Download the result and confirm its pixel dimensions and size in your file manager before uploading.

What file size to expect

There is no single honest kB figure for a 413 × 531 photo. A plain, evenly lit background and a sharp face compress well; grainy low-light shots, patterned clothing and busy backgrounds need many more bytes at the same quality.

Pixel counts still tell you how hard a target will be. 630 × 810 has about 2.3 times the pixels of 413 × 531, and 413 × 531 has nearly 4.8 times the pixels of a 200 × 230 bank photo. That is why a 20–50 kB limit pairs sensibly with 200 × 230, and why a large passport size comes with a generous range such as GOV.UK’s 50 kB to 10 MB. If a form gives you a small kB limit and no pixel rule, fewer pixels at good quality usually look better than many pixels at poor quality. Without an exact size set, the compressor applies that idea automatically: if a target would need very low quality, it reduces the dimensions instead. The 50 kB preset is a quick start for strict limits, and the guide to reducing passport photo size covers clarity at smaller targets.

Final check before uploading

Open the downloaded file, not the original, and confirm that:

• its pixel dimensions match the form exactly, or fall within its minimum and maximum
• the face is not stretched and the head and shoulders are not cut off
• its size is inside both ends of the kB range, remembering that this site counts 1 kB as 1,000 bytes
• it is the format the field accepts, usually JPG
• the background, lighting and face size follow the authority’s own photo rules

If a correct-looking file is still refused, the upload rejected checklist covers byte rounding, wrong formats and other causes. Different portals pair different pixel and kB rules, so check each field against its current notice; the Indian government image size guide collects several examples with their sources.