Passport Photo Size: Pixels, Ratios and File Size Explained

The portal rejected your photo, and the message names a number: 600 by 600 pixels, or 35 by 45 millimetres, or a file no bigger than 50KB. A phone photo fails all three at once — it is thousands of pixels wide, the wrong shape, and several megabytes. Fixing it means getting three numbers right in the right order: crop to the ratio, resize to the pixels, then compress under the file-size cap. The Image Resizer handles the middle step, and this guide covers all three, with the maths shown so you can check every number yourself.

The order matters more than any single step. Resizing first and cropping second wastes work, because the crop throws away pixels you just sized. Compressing first and resizing second wastes quality, because compression discards detail the resize would have removed anyway. Crop to the ratio, resize to the exact pixels, compress to the cap — and check the portal spec before you start, because the numbers change between portals and the numbers in this guide are the common examples, not a promise about yours.

Read the spec first: pixels, millimetres and kilobytes

Every portal states its photo spec in some combination of three units, and you need all three before touching the photo. Dimensions in pixels are the most direct: the US visa photo is 600 by 600 pixels, a square 2 by 2 inches at 300 dots per inch. Dimensions in millimetres need converting: a 35 by 45 millimetre photo at 300 DPI is 413 by 531 pixels, because 35 millimetres is 1.38 inches and 1.38 times 300 is 413, and 45 millimetres is 1.77 inches and 1.77 times 300 is 531. The file-size cap is the third number: common caps are 20KB for a signature, 50KB for a passport photo and 100KB or 200KB for general uploads. If your portal states a DPI, note it — the same 35 by 45 millimetres at 200 DPI is only 276 by 354 pixels, a different photo entirely.

• 600 × 600 px — US visa photo, 2 × 2 in at 300 DPI, square (1:1).
• 413 × 531 px — 35 × 45 mm at 300 DPI, portrait (7:9).
• 276 × 354 px — 35 × 45 mm at 200 DPI, portrait (7:9).
• 20KB / 50KB / 100KB — typical signature / passport photo / general upload caps; check your portal.

Two warnings about specs. First, a portal that says “35 by 45 millimetres” without a DPI has not actually given you a pixel size — ask, or assume 300 DPI and verify against the portal’s preview after upload. Second, specs change: portals update their requirements without notice, so the numbers above are the common examples to work from, and your portal’s own page is the authority.

Step 1 — crop to the ratio

A ratio is the shape of the photo, and it is fixed before any resizing happens. A 600 by 600 photo is square, a ratio of 1 to 1. A 413 by 531 photo is portrait, a ratio of 7 to 9 — 413 divided by 531 is 0.78, and 7 divided by 9 is 0.78. Your phone photo is almost certainly landscape, 4 to 3 — a 4,032 by 3,024 photo, for example — so it matches neither shape, and no amount of resizing will fix that: resizing scales the whole photo, it never changes its shape.

Open the Image Cropper, upload the photo, and set the X, Y, Width and Height boxes to the frame you want. For a square photo from a 4,032 by 3,024 image, the height is the limit: set Width and Height to 3,024 and the X offset to 504, which centres the square — (4,032 minus 3,024) divided by 2 is 504. For a 7 to 9 portrait from the same photo, the height is again the limit: Height 3,024, Width 3,024 times 7 divided by 9, which is 2,352, and X offset (4,032 minus 2,352) divided by 2, which is 840. The preview draws the frame over your photo, so move it until the face sits right, then download. The cropped file is a PNG, and it is still full-size — the pixel count comes next.

Step 2 — resize to the exact pixels

Open the Image Resizer and upload the cropped photo. The Width and Height boxes show the photo’s real dimensions — a square crop from the example above reads 3,024 by 3,024 — and the Keep aspect ratio box is ticked by default. With it ticked, typing one side fills in the other to match: type 600 into Width on a square photo and Height becomes 600 by itself, because 600 times 3,024 divided by 3,024 is 600. For the 7 to 9 portrait, type 413 into Width and Height becomes 531, because 413 times 3,024 divided by 2,352 is 531. That is the lock doing the ratio maths for you — it preserves whatever shape you give it, right or wrong, which is why the crop had to come first.

Two details to know. First, the resizer also has a resize-by-percentage mode: entering 50 halves both sides, so a 4,032 by 3,024 photo becomes 2,016 by 1,512, and 25 gives 1,008 by 756. Percentages suit a form that only states a maximum width, but they cannot hit an exact pixel target — use the Width and Height boxes when the portal names exact pixels. Second, untick Keep aspect ratio only when the portal demands a frame your photo does not match — typing 600 by 600 into a 4 to 3 photo with the lock off stretches the face wider, and a stretched passport photo is a rejected passport photo. Crop first; never stretch.

One honest note: the resizer downloads a PNG. PNG is lossless, which is good for sharpness and bad for file size — a 600 by 600 photographic PNG can still be several hundred kilobytes, well over a 50KB cap. The pixels are right and the file size is not, which is exactly what step 3 fixes.

Step 3 — compress under the KB cap

Open the Image Compressor and upload the resized PNG. The quality slider starts at 80% and moves in 5% steps down to 10%, and after each run the tool shows the original size, the compressed size and the percentage saved. Start at 80% and step down until the result reads under your cap — and aim 5 to 10% under it, not exactly at it, because portals count bytes their own way. A 600 by 600 photo at 80% quality typically lands well under a 50KB cap, but a plain background compresses far better than a busy one, so read the number after each run rather than trusting a rule of thumb.

The compressor also fixes the format problem from step 2 for free: it keeps PNG input as PNG, but converts everything else to JPEG — and a JPEG of a photograph is dramatically smaller than a PNG of the same photo at the same quality, because JPEG is built for photographs and PNG is built for exactness. If your resized PNG refuses to shrink, convert it to JPEG first with the Image Format Converter, then compress the JPEG: the same photo will usually land under the cap at 70 to 80% quality. For the full method, How to Compress an Image to 100KB for an Online Form walks through the quality-step descent in detail.

Worked example: phone photo to a 600 by 600 visa photo

Take a typical phone photo: 4,032 by 3,024 pixels, 12.19 megapixels, 2.4MB on disk. The target is a US visa photo, 600 by 600 pixels under a 50KB cap. Crop first: a centred square, Width and Height 3,024, X offset 504, gives a 3,024 by 3,024 square. Resize second: Width 600 with the aspect lock on gives Height 600 automatically — the photo is now 600 by 600, which is 14.9% of its original width. Compress third: run it at 80% quality and read the result — a plain-background portrait typically lands well under the cap, and if yours does not, step down in 5% increments until it does. From 2.4MB to under 50KB is a reduction of about 98%, and every number in the chain is one you can check on the tools as you go.

Mistakes that get photos rejected

• Stretching instead of cropping. Unticking the aspect lock and typing the target pixels distorts the face; portals check proportions.
• Uploading the multi-megabyte original. A phone photo at 2.4MB is roughly 49 times a 50KB cap — resize and compress before the portal ever sees it.
• Screenshotting the photo instead of using the original file. Screenshots add compression artefacts before you start, and a screenshot of a photo is lower resolution than the photo itself.
• Cropping out required content to hit a size. Portals reject photos missing the required head size or margins; shrink dimensions instead of cutting content.
• Re-compressing the compressed file. Each pass throws away more detail; always work from the original or the resized original, which is what the compressor does on every run.

Why an ID photo should never leave your browser

A passport photo is an identity document, and it is the last thing to hand to a stranger’s server. All three tools in this guide run entirely in your browser: the photo is drawn onto a canvas element and re-encoded on your device, so nothing is uploaded, stored or logged, and no copy of your face sits on anyone else’s machine. That is the same on-device rule the whole site runs on, explained in Which Online Tools Upload Your Files — and Which Never Do. If a photo tool asks you to create an account before it will resize an image, the photo is the product. The rest of the image tools work the same way.