What is a PNG File?

What Is a PNG File?

PNG (Portable Network Graphics) is a raster image format that uses lossless compression. Unlike JPG, which permanently discards some pixel data to reduce file size, PNG stores every pixel exactly as it appears — meaning the image quality never degrades no matter how many times you save or re-open the file.

The file extension is .png.

Key Features of PNG

Lossless compression: No quality loss on save or re-export. Ideal for files you plan to edit repeatedly.

Alpha channel transparency: PNG supports full alpha transparency — individual pixels can be anywhere from fully opaque to fully transparent. This is essential for logos placed over varying backgrounds.

24-bit colour: PNG supports full 24-bit colour depth (over 16 million colours).

Wide software support: Supported by every browser, operating system, and design tool.

PNG vs JPG: When to Use Each

PNG vs WebP

WebP lossless mode produces files 26% smaller than equivalent PNGs at the same quality. If you are building a website and do not need legacy software compatibility, converting PNGs to WebP using our PNG to WEBP converter is a direct performance win.

How to Reduce PNG File Size

PNG files can often be reduced by 40–70% without any visible quality loss using a PNG compressor. Use our Image Compressor to compress your PNG files for free.

The History: PNG as a GIF Replacement

PNG was created in 1995 as a response to a patent dispute over GIF (Graphics Interchange Format). GIF's compression algorithm (LZW) was patented by Unisys, and there were concerns about whether web developers could use GIF freely. PNG was designed as a patent-free, feature-richer alternative.

By the time the patent issues were fully resolved in 2004, PNG had become the standard format for lossless web graphics, a position it still holds.

How PNG Compression Works

PNG uses lossless compression — no image data is discarded. The compression algorithm (DEFLATE, based on LZW and Huffman coding) works by finding and encoding repeating patterns in the image data.

This means: simple images (flat colours, geometric shapes, images with large areas of solid colour) compress very efficiently in PNG. Complex photographic images with fine detail and gradients everywhere don't compress as efficiently — these are better suited to JPG or WebP.

The Alpha Channel: PNG's Defining Feature

PNG supports alpha transparency — the ability for pixels to be partially or fully transparent. This is what makes PNG essential for:

Logos and icons: A company logo on a transparent background can be placed over any background colour without a visible box around it.

UI elements: Buttons, overlays, and interface elements in apps and websites often have transparency.

Design work: Product photos with removed backgrounds, stickers, and design assets used in composition work all require transparency support.

JPG does not support transparency at all. WebP does, but has less universal tool support. For transparency needs, PNG is the most compatible choice.

When PNG Is the Wrong Choice

For photographs and complex-colour images, PNG is significantly less efficient than JPG or WebP. A high-quality photo saved as PNG is typically 8–20× larger than the same image in JPG. For web use where you don't need transparency, JPG or WebP is almost always the right choice for photos.

PNG is the right choice when: you need transparency, you'll edit the image repeatedly and need to avoid generational quality loss, or the image has primarily flat colours and sharp edges (logos, icons, screenshots).

PNG in India: Practical Notes

Many Indian government portals and business systems accept PNG along with JPG for photo uploads. PNG is the correct format for logo files used in business registration, trademark applications, and official document templates. For document scan uploads, JPG is usually more space-efficient than PNG while still meeting quality requirements.

weFixPDF's PNG to JPG tool handles conversion when file size needs to be reduced, and JPG to PNG when you need to switch back for editing or transparency purposes.