The short version
File size is how much room the file takes on disk, in KB or MB. Pixel dimensions are how many dots wide and tall the picture is. Aspect ratio is its shape. Each has its own fix: compress for bytes, resize for dimensions, crop for shape. Read the message again and work out which of the three it is complaining about before you change anything.
Three properties that all get called size
| What it is | Measured in | The message tends to say | The fix |
|---|---|---|---|
| File size | KB, MB | Under 2 MB, file too large, at least 50 KB | Compress |
| Pixel dimensions | width × height in pixels | At least 600 pixels wide, image too small, maximum 1200 pixels | Resize |
| Aspect ratio | a shape: 1:1, 4:5, 16:9 | Must be square, wrong proportions, does not meet requirements | Crop |
| Resolution, or DPI | pixels per inch | Must be 300 DPI | Nothing. See below |
The last row wastes the most time. DPI is a note inside the file saying how large to print it, and it changes nothing about the picture. A request for 300 DPI is really a request for enough pixels, which is why the US State Department describes a two inch photo scanned at 300 pixels per inch and then states the requirement in pixels anyway.
To see what you have: on Windows, right-click the file, choose Properties, then the Details tab, where dimensions and size are both listed. On a Mac, select it and press Command-I. Or drop it into any image tool here, which prints the width and height beside the before and after byte count.
In this order, and the order matters
- Shape first. If the form wants a square or a fixed ratio, crop before anything else. It cuts from the centre at full resolution rather than stretching, so faces stay the right width.
- Then dimensions. Resize sets a maximum width and lets the height follow, so the shape you just chose survives. It only reduces.
- Then bytes. If the file is still too heavy, compress it. Quality 85 is rarely noticeable on photographs; at low settings, flat areas such as a plain background go blotchy, and official photo rules ask for a clear picture.
The other order wastes the work: cropping removes pixels, so a crop applied after a careful resize can drop you back under a minimum you had just met.
Three published specs, and how differently they are written
Quoted from the bodies that publish them, with the links, to show the shape of the problem rather than to be relied on. Requirements change and vary by country, and the only specification that counts for your application is the one on the authority's own page. Check it, then come back and make the file.
| Where | Pixel dimensions | File size | Other |
|---|---|---|---|
| US visa digital photo travel.state.gov | 600 × 600 minimum, 1200 × 1200 maximum | 240 KB or less | Square, JPEG, sRGB colour |
| UK passport digital photo gov.uk | At least 600 wide and 750 tall | At least 50 KB, no more than 10 MB | Unaltered by computer software; a photo taken on your own device should not be cropped |
| LinkedIn profile photo LinkedIn Help | 400 × 400 up to 7680 × 4320 | 8 MB maximum | PNG or JPG, no GIFs |
Read across those rows and the trap is obvious. The US spec caps the file at 240 KB and demands a perfect square; the UK spec sets a floor of 50 KB and minimums of 600 by 750 pixels. A small square file made for the US fails the UK minimums, a UK file over 240 KB fails the US cap, and no error message will explain that.
Where the mismatch comes from
A phone camera produces images several thousand pixels across, a number chosen with no upload form in mind. Forms carry two opposing worries: a picture big enough to identify a face, and a file small enough to store a million of them. So a form has both a floor and a ceiling, and a straight-off-the-camera photo often misses both at once. Automatic cropping makes it worse: a photo that looks square in your gallery is frequently not square in the file, because the gallery is showing you a square window onto a rectangle. The form reads the file, not the window.
The cases where the obvious fix does not work
- You cannot reach the pixel minimum. If the form wants 600 by 600 and your photo is 400 by 400, enlarging adds no information. It guesses at pixels, which reads as blur, and official specs such as the UK's ask for a photo that is clear and in focus. Take the picture again.
- You compressed past a floor. A minimum file size, such as the UK's 50 KB, is really asking for a picture with detail in it. Push the quality down to sneak under a maximum elsewhere and you fall through that floor. Lower the dimensions instead.
- The square crop ate the margin. Official specs describe how much space must sit above the head and how tall the head must be. A centre crop ignores all of that. Crop looser, then check against the authority's own diagram.
- It was never about size. If the message mentions the file type, resizing cannot help. An iPhone photo is usually the culprit and has its own page; a PNG that needs to be a JPG is a one-step conversion; unsupported file type covers the rest. If nothing was said at all, try why was my file rejected or file too large.
- It passed, and you sent more than you meant to. A phone photo carries the date, the camera and often the coordinates of where it was taken. Remove EXIF data shows what yours holds and strips it. Every tool here works in the tab, and you can verify that in a minute.
Frequently asked questions
Last reviewed 2 October 2026