Why won't my image upload?

The short answer

An upload form can reject a picture for five reasons. They are nowhere near equally likely, and the error message is not a reliable guide to which one you are looking at — plenty of forms report every failure with the same sentence.

1. The file is over the size limit. The cause most of the time, and the easiest to fix.
2. The picture has too many pixels. A separate limit from the file size, and one that is frequently not mentioned.
3. The format is not one the site accepts. HEIC from an iPhone, WebP from a download.
4. The format is accepted, but the site got its own list wrong. Classically a .jpeg hitting a list of allowed extensions that only has .jpg on it.
5. The name says one thing and the file is another. A renamed file, rather than a converted one.

Work down that list in order and you will land on the right one faster than by reading the error.

1. The file is over the size limit

Most upload forms cap the number of bytes they will take. Two megabytes and five megabytes are the common limits, and a photo straight off a modern phone is usually somewhere between three and six — so the typical picture fails the typical form by a small margin.

The confusing part is that the limit is often invisible until you break it, and the error frequently says something vaguer than it needs to: upload failed, please try again, or nothing at all beyond a spinner that stops.

There are two ways to make a file smaller and they are not equally good. Reducing the pixel dimensions is the one to reach for first. It removes detail by averaging neighboring pixels together, so the result stays clean, and it usually removes far more weight than anything else you can do. Lowering the quality setting is the second step, and it works by approximating detail rather than discarding it evenly, which is where the blocky look comes from when it is pushed hard.

We tested the two approaches against each other by hitting the same target file size with each, and resizing won every time — by a wider margin the tighter the budget got. The measurements are in is it better to resize or compress an image. If you want to know why the file was so big to begin with, that is a separate question with its own answer in why is my JPEG so big.

2. The picture has too many pixels

This is the second most common cause and it catches people out because it is a different limit that produces an almost identical error. A form can accept your two-megabyte file and still refuse it for being 6000 pixels wide.

Sites cap dimensions for reasons that have nothing to do with storage. Decoding a very large image costs memory on their server, thumbnails have to be generated from it, and an avatar slot that is 200 pixels across has no use for anything approaching a camera original. Forums, ticketing systems and older content management systems are the usual places to meet a dimension cap.

The tell is that compressing the file harder does not help at all. Quality settings change bytes, not pixels — a photo saved at quality 30 has exactly as many pixels as it did at quality 95. If the file keeps shrinking and the form keeps refusing, you are fighting the wrong limit.

Drop the picture into the resizer and it shows the current width and height before you change a thing, which is often enough to tell you which of the first two causes you have.

3. It is a format the site does not accept

Two formats account for most of these, and neither is anything you chose.

HEIC, from an iPhone

Recent iPhones save photos as HEIC rather than JPEG, because it stores the same picture in roughly half the space. The catch is that support outside Apple software is patchy, and most upload forms will not take one. You can stop it recurring in Settings → Camera → Formats → Most Compatible, which switches the camera back to JPEG. For photos you already have, our HEIC to JPG converter turns them into JPGs in your browser, a whole folder at once, without uploading them anywhere. Sending them through Mail or Messages, or dragging them out of Photos on a Mac, also converts them on the way out.

WebP, from a download

If you saved a picture from a website, there is a good chance it came down as WebP, which is what most sites now serve. It is a perfectly real image format and a good one, but plenty of upload forms have never heard of it. Our WebP to JPG converter turns it into something universally accepted, and what is a WebP file covers where they come from.

Anything else — AVIF, BMP, TIFF, a PNG where only JPGs are wanted — is the same problem with a different name, and the image converter handles a mixed batch of them in one pass. If the form specifically wants a JPG and you have a PNG, PNG to JPG is the direct route, and it lets you pick what color goes behind any transparent areas, because JPG cannot store transparency at all.

4. A format the site says it accepts, but does not

Sometimes the file is exactly what the form asked for and it is still refused. When that happens, the site is usually wrong rather than you.

Upload forms commonly check the end of the filename against a list of allowed extensions, and that list is typed by hand. Three ways it goes wrong:

• .jpeg is missing and .jpg is there. The most common version by a distance. They are the same format — the shorter spelling exists only because early Windows allowed three letters after the dot — so renaming your file from photo.jpeg to photo.jpg is a complete fix that changes nothing inside the file. Full story in JPG vs JPEG.
• The check is case sensitive. A camera that writes IMG_0042.JPG in capitals can fail a list containing only the lowercase spelling. Rename it in lowercase.
• The file has no extension at all. Files that have been through several apps sometimes lose it. Add the right one back.

On Windows you may need to make extensions visible first: in File Explorer, open the View menu and tick File name extensions. On a Mac, click the filename once, pause, then click again to edit it. Both will ask whether you really meant to change the extension. You did.

5. The name says JPG and the file is not

This is the least common of the five and the most bewildering when it happens, because the picture opens perfectly on your own computer.

Every image format begins with a few identifying bytes. A PNG starts with one pattern, a JPEG with another, and your operating system reads those bytes to decide how to open the file — which is why a mislabeled picture still displays normally at home. Careful upload forms read the same bytes, compare them with the extension, and reject the file when the two disagree. That check is there for a good reason, since it is also how you stop someone uploading a program that has been named cat.jpg.

How a file ends up lying about itself:

• Someone renamed it. Changing .png to .jpg changes the label on the box, never the contents — which is exactly why renaming is the fix for the previous section and useless here.
• A browser download saved a WebP under a .jpg name, because the site served one format under a link promising another.
• An app exported with the wrong extension, or a messaging app saved something it had already re-encoded.

The fix is a real conversion rather than a rename. Opening a picture in a browser tool decodes it back to plain pixels and encodes it again from scratch, so what comes out genuinely is the format it claims to be — a PNG mislabeled as a JPG goes through PNG to JPG and comes back an actual JPG. If you are not sure what you have, the image converter takes whatever the browser can read and gives you back the format you pick.

What to try, in order

The order is chosen so that each step is cheaper than the one after it, and so that a failure tells you something.

1. Look at the file size and the dimensions. Right-click and check properties, or drop it into the resizer, which shows both before you change anything. Most uploads fail here and stop being a mystery immediately.
2. Resize to something sensible. 1600 pixels wide is generous for a full-width web image, 800 is plenty inside a column, and a profile picture needs a few hundred. This one costs no visible quality.
3. Then compress if you are still over the limit. Quality 80 to 85 is where most of the remaining size goes and almost none of the appearance does.
4. Rename .jpeg to .jpg, in lowercase. Free, instant, and it fixes a surprising number of forms.
5. Convert properly if none of that worked. Run it through a converter so the file really becomes a JPG or PNG rather than being labeled one, which also settles the case where the extension was lying.

One thing worth saying plainly: none of this needs an account, an app, or your file leaving your machine. Every tool here does its work in the browser on your own computer, which matters more than usual when the thing you are trying to upload is a passport photo or a document for a form.

Frequently asked questions

Why won't my image upload?

In most cases the file is larger than the site's size limit, which is commonly 2 MB or 5 MB and often not stated anywhere until you fail it. The next most common cause is pixel dimensions, which many forms cap separately from file size. After those come three format problems: a format the site genuinely does not accept, a format it claims to accept but has not listed properly, and a file whose extension does not match what is actually inside it.

How do I make a photo small enough to upload?

Reduce the pixel dimensions first, then lower the quality if you still need to. A phone photo is typically around 4000 pixels wide, and almost nothing on a website displays an image wider than about 1600, so resizing to 1600 usually removes most of the file size without any visible change. Lowering the quality setting is the second step, not the first, because it costs visible detail and saves less.

Why does a site say my file type is not supported when it is a JPG?

Usually one of two reasons. The site's list of allowed extensions has .jpg on it but not .jpeg, so renaming the file fixes it instantly. Or the file is not really a JPG despite its name, which happens when a picture has been renamed rather than converted. In that second case the site is right and the file needs a genuine conversion, not another rename.

Why won't my iPhone photos upload?

Recent iPhones save photos as HEIC by default, and most upload forms do not accept HEIC. You can stop it happening again in Settings, under Camera, then Formats, by choosing Most Compatible, which makes the camera save JPEGs instead. For photos you already have, the free HEIC to JPG converter on this site turns them into JPGs in your browser without uploading them.

Why does an upload fail when the picture looks completely fine on my screen?

Because your computer opens a file by reading what is inside it, while an upload form usually judges it by the name first. A screenshot renamed from .png to .jpg still opens perfectly everywhere on your machine, and is still a PNG. Servers that check the first few bytes of the file will see the mismatch and reject it, sometimes with an error that mentions neither the format nor the name.

Does compressing an image make it look worse?

Less than most people expect, and resizing does not do it at all. Reducing the pixel dimensions removes detail by averaging neighboring pixels together, which looks clean; lowering the JPEG quality setting approximates detail instead, which is what produces the blocky look at aggressive settings. Between about 80 and 85 quality, most of the file size disappears and very little of the visible quality does.