How do I set the Content-Type for .png in Nginx?

Make sure image/png png; is listed in the types block (usually in /etc/nginx/mime.types) and reload Nginx.

Should I gzip .png files?

No — the format is already compressed, so HTTP compression gives no benefit.

.png MIME Type — image/png

image/png

MIME type for .png

Images

What is the MIME type of .png files?

The MIME type (media type) for PNG image files with the .png extension is image/png. Lossless raster format with transparency. Already compressed — do not gzip.

Content-Type header

Content-Type: image/png

Server configuration

Server	Configuration
Nginx (`mime.types` or `types {}`)	`image/png png;`
Apache (`.htaccess`)	`AddType image/png .png`
IIS (`web.config`)	`<mimeMap fileExtension=".png" mimeType="image/png" />`
Node.js / Express	`res.type('png')` or `res.setHeader('Content-Type', 'image/png')`
Amazon S3	Set `Content-Type: image/png` on the object (metadata), or pass `--content-type image/png` to `aws s3 cp`

Should .png files be compressed?

No. PNG image files are already compressed internally, so gzip or Brotli would waste CPU and barely reduce — sometimes even increase — the size. Leave image/png out of your compression configuration.

Why the MIME type matters

Browsers decide what to do with a response — render, run, play or download — from the Content-Type header, not the file extension. With X-Content-Type-Options: nosniff, a wrong type causes stylesheets and scripts to be blocked outright. For uploads, never trust the type sent by the client; check the file’s content (its magic bytes) on the server.

.png MIME Type: image/png