MIME Type for PNG | What Is the Correct Content Type

MIME Type for PNG - What Is the Correct Content Type?

The correct MIME type for PNG files is image/png. Always use this in your HTML, server configuration, and HTTP headers. It is the official registered type and works in all browsers.

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This guide explains everything you need to know about MIME type for PNG. You will learn what MIME types are, the correct type for PNG, how to use it properly, and common mistakes to avoid.

If you have ever built a website or worked with web servers, you have likely encountered MIME types. They tell browsers what kind of file they are receiving. Getting them wrong can cause images not to display, files to download instead of showing, or even security issues.

Let us clear up everything about PNG MIME types.

What is a MIME type?

MIME stands for Multipurpose Internet Mail Extensions. It was originally created for email attachments but is now used everywhere on the web.

A MIME type tells the browser or client what kind of file it is receiving. It has two parts: a type and a subtype, separated by a slash. For example:

text/html – HTML document
image/jpeg – JPEG image
image/png – PNG image
application/pdf – PDF document

When your web server sends a file, it includes a Content-Type header with the correct MIME type. If the MIME type is wrong, the browser might display the file incorrectly or offer it as a download.

What is the MIME type of a png?

The correct MIME type for PNG files is image/png.

This is the official MIME type registered with IANA (Internet Assigned Numbers Authority). It applies to all PNG files with the .png extension.

When your web server sends a PNG image, it should include this header:

Content-Type: image/png

This tells the browser "this is a PNG image" and ensures it displays correctly.

What is the MIME type in an image?

The MIME type for an image tells the browser what kind of image it is. Different image formats have different MIME types:

Format	File Extension	MIME Type
PNG	.png	`image/png`
JPEG / JPG	.jpg, .jpeg	`image/jpeg`
GIF	.gif	`image/gif`
WebP	.webp	`image/webp`
SVG	.svg	`image/svg+xml`
TIFF	.tiff, .tif	`image/tiff`
BMP	.bmp	`image/bmp`
ICO	.ico	`image/vnd.microsoft.icon` or `image/x-icon`

For PNG, always use image/png. This is the standard and works everywhere.

Is MIME type jpg or JPEG?

The correct MIME type for JPG files is image/jpeg, not image/jpg. This is a common mistake.

image/jpeg is the official registered type. image/jpg is not a valid MIME type and may not work in all situations.

For more details, read our guides on content type JPG and is image/jpg a valid MIME type.

What is a MIME attachment png?

A MIME attachment is a file sent via email using MIME encoding. When you attach a PNG image to an email, it is sent as a MIME attachment with the content type image/png.

The email client includes headers that specify:

Content-Type: image/png – tells the receiving client it is a PNG
Content-Disposition: attachment – tells the client to treat it as an attachment (or inline to display)
Content-Transfer-Encoding – specifies how the file is encoded (usually base64)

This is why emails with images can display them inline or as attachments – the MIME type determines how they are handled.

Why does the correct MIME type matter?

Using the correct MIME type is important for several reasons:

Browser compatibility 📌 Browsers rely on MIME types to know how to handle files. A PNG with the wrong MIME type might not display at all.
Security 📌 Incorrect MIME types can lead to security issues. For example, if a server sends HTML as image/png, it might bypass security filters.
SEO 📌 Search engines use MIME types to understand content. Incorrect types can affect indexing.
User experience 📌 Files open correctly instead of downloading unexpectedly.
API consistency 📌 APIs that validate MIME types may reject files with incorrect types.

How to use the correct PNG MIME type in HTML

In HTML, you do not set the MIME type directly for images. The server handles this. However, when using the <picture> element with multiple formats, you specify the type attribute:

<picture>
  <source srcset="image.avif" 
type="image/avif">
  <source srcset="image.webp" 
type="image/webp">
  <img src="image.png" 
alt="Description">
</picture>

For the PNG fallback, you do not need to specify a type. But if you were to specify, it would be type="image/png".

How to set the correct PNG MIME type on servers

On Apache

In your .htaccess file or Apache configuration:

AddType image/png .png

On Nginx

In your mime.types file or nginx.conf:

types {
    image/png    png;
}

On IIS

In your web.config file:

<staticContent>
  <mimeMap fileExtension=".png" 
mimeType="image/png" />
</staticContent>

How to set the correct PNG MIME type in APIs

Node.js / Express

res.setHeader('Content-Type', 'image/png');
res.sendFile('image.png');

Python / Flask

from flask import send_file
response = send_file('image.png', 
mimetype='image/png')

PHP

header('Content-Type: image/png');
readfile('image.png');

Java / Spring

@RequestMapping(value = "/image", 
produces = MediaType.IMAGE_PNG_VALUE)
public @ResponseBody byte[] getImage() {
    // return image bytes
}

Common MIME type mistakes with PNG

Using image/x-png instead of image/png (some older systems used this, but it is not standard)
Using uppercase letters (image/PNG)
Forgetting to configure the server for .png extensions
Sending application/octet-stream for PNG images (forces download instead of display)
Using the wrong MIME type in email attachments

How to check the MIME type of a PNG file

You can check what content type your server is sending using browser developer tools:

Open browser DevTools (F12)
Go to the Network tab
Reload the page
Click on a PNG image file
Look for "Content-Type" in the response headers

You should see content-type: image/png. If you see something else, your server needs reconfiguration.

You can also use command-line tools like curl:

curl -I https://example.com/image.png

Look for the Content-Type header in the response.

What about other image MIME types?

For reference, here are the correct MIME types for common image formats:

Format	File Extension	MIME Type
PNG	.png	`image/png`
JPEG / JPG	.jpg, .jpeg	`image/jpeg`
GIF	.gif	`image/gif`
WebP	.webp	`image/webp`
AVIF	.avif	`image/avif`
TIFF	.tiff, .tif	`image/tiff`
BMP	.bmp	`image/bmp`
SVG	.svg	`image/svg+xml`
ICO	.ico	`image/vnd.microsoft.icon` or `image/x-icon`

Frequently asked questions about PNG MIME type

Is the MIME type case-sensitive?

Yes. MIME types are case-sensitive and should always be lowercase. image/PNG may not be recognized correctly.

Can I use image/x-png?

Some older systems used image/x-png, but this is not the standard. Always use image/png for maximum compatibility.

Does the file extension affect the MIME type?

No. The MIME type is determined by the server configuration, not the file extension. A properly configured server will send image/png for all .png files.

What happens if I use the wrong MIME type?

The image may not display, or the browser might try to download it instead of showing it. In some cases, it could cause security warnings.

Remember: The correct MIME type for PNG files is always image/png. Configure your server correctly, and your images will display properly for all users.

The bottom line: MIME type for PNG

The correct MIME type for PNG files is image/png. This is the official, registered type that works in all browsers and applications.

Using the correct MIME type ensures:

PNG images display correctly in all browsers
No unexpected downloads
Proper API validation
Better security
Standards compliance

Configure your server correctly, use the right MIME type in your APIs, and you will avoid common errors that cause images not to display.

For more information about JPG MIME types, read our guide on JPG content type.

Summary: The correct MIME type for PNG files is image/png. Not image/x-png. Configure your server with AddType image/png .png (Apache) or the equivalent for your platform. Always use lowercase. This ensures your PNG images display correctly in all browsers.