PNG vs JPG: Which Image Format Should You Use?

The two most widely used image formats in the digital world today are PNG and JPG. Both have very different characteristics even though they're both used to store images. I was initially confused about which one to use myself. When I first started learning graphic design, I always saved all images in PNG format because I thought "the important thing is good quality." The result? My hard drive filled up in no time because of the large PNG file sizes for photos that didn't actually need transparency. In this article, we'll discuss in depth the comparison between PNG and JPG, including the pros and cons of each, and when you should use which format.

Choosing the right image format isn't just about visual quality -- it also involves file size, compatibility, web page loading speed, and many other factors. Mistakes in choosing an image format can result in poor quality, excessively large file sizes, or even incompatibility with the platform you're using. Let's break them down one by one to help you make the right decision.

What Is the JPG Format?

JPG (or JPEG, which stands for Joint Photographic Experts Group) is an image format developed in 1992 by the Joint Photographic Experts Group. This format was specifically designed for photos and images with complex color gradients, such as landscape photos, human portraits, and other photographic images.

JPG works by using lossy compression techniques, meaning some image data is permanently removed to reduce file size. This process exploits the human eye's inability to distinguish very subtle color changes. By removing fine details that are nearly imperceptible to the human eye, JPG can significantly reduce file size without a too-obvious drop in quality.

One of JPG's main advantages is its flexibility in adjusting compression levels. When saving a file as JPG, you can choose quality from 1% to 100%. The higher the quality selected, the larger the file size, and vice versa. For web use, 70-85% quality usually provides excellent results with optimal file sizes.

What Is the PNG Format?

PNG (short for Portable Network Graphics) is an image format developed in 1996 as a replacement for the GIF format, which had limitations. PNG was designed to store high-quality images without data loss during compression.

Unlike JPG, which uses lossy compression, PNG uses lossless compression. This means all original image data is fully preserved, and when the file is opened again, the image will look exactly as it did when first saved. Not a single pixel is lost or changed during the saving process.

PNG's main advantage is its support for transparency (alpha channel). This format allows you to create images with transparent backgrounds, which is extremely useful for logos, icons, and web graphics. Additionally, PNG is excellent for storing images with sharp edges, such as text, diagrams, and simple charts.

Complete PNG vs JPG Comparison

Feature	JPG	PNG
Compression Type	Lossy (data loss)	Lossless (no data loss)
File Size	Small (suitable for photos)	Large (suitable for graphics)
Quality	Depends on compression level	Always original quality
Transparency	Not supported	Supported (alpha channel)
Animation	Not supported	Not supported
Colors	Up to 16.7 million colors (24-bit)	Up to 4.3 trillion colors (48-bit)
Best For	Photos, gradient images	Logos, text, graphics, screenshots
Compression	Very efficient for photos	Less efficient for photos
File Extension	.jpg or .jpeg	.png

When Should You Use JPG?

JPG is the best choice in the following situations:

• Digital photos: If you have photos from a camera or smartphone, JPG is the most appropriate choice. This format is specifically designed to efficiently handle the complex color gradients in photos.
• Images with many colors: Images that have thousands or millions of different colors, such as nature landscapes, digital paintings, or photographic images, will be much more efficiently stored in JPG format.
• Web and social media: Most social media platforms like Instagram, Facebook, and Twitter use JPG compression by default. Uploading images in JPG format results in smaller file sizes and faster loading times.
• Email and attachments: When sending images via email, small file sizes are very important. JPG allows you to send good-quality images with relatively small file sizes.
• When file size is a priority: If you have limited storage space or bandwidth, JPG is the most efficient choice for images with many colors.

When Should You Use PNG?

PNG is the best choice in the following situations:

• Logos and web graphics: Company logos, icons, and web graphics should be saved in PNG format because of their sharp quality and transparency support.
• Screenshots: Screen screenshots contain a lot of text and graphic elements with sharp edges. PNG format maintains this quality without compression artifacts.
• Images with transparency: If you need images with transparent backgrounds, PNG is the only choice between these two formats.
• Text in images: Images containing text, such as infographics or presentations, will look much sharper in PNG format.
• Image editing: When working with images in editing software like Photoshop, saving in PNG format ensures no quality is lost when the file is opened and saved repeatedly.
• Images with few colors: For simple graphics with a limited number of colors, PNG often produces smaller file sizes than JPG.

Impact on Website Speed

Web page loading speed is a crucial factor that affects user experience and SEO rankings. Google has confirmed that page loading speed is one of the ranking factors in search. Therefore, choosing the right image format has a significant impact on your website's performance.

My own experience proves this. My first website was full of PNG photos that were 3-5MB per image. After I converted them all to JPG at 80% quality, the sizes dropped by an average of 70% and loading time went from 8 seconds to 2 seconds. No need to buy more expensive hosting -- just change the image format.

For photos and colorful images on your website, using JPG format with proper compression (usually 75-85% quality) can reduce file sizes by 60-80% compared to PNG without significant quality loss for visitors. This means your web pages will load faster, visitors won't need to wait long, and Google will give your website a better ranking.

Conversely, using PNG format for photos on your website will result in much larger file sizes than necessary, slow down page loading, and potentially cause visitors to leave because of waiting too long. Studies show that adding 1 second to page loading time can reduce conversions by up to 7%.

Pro tip: Use tools like TinyPNG or Squoosh to optimize images before uploading them to your website. Both tools can effectively compress JPG and PNG images without too-obvious quality loss.

What About Other Formats?

Besides PNG and JPG, there are several other image formats worth considering:

• WebP: A format from Google that offers better compression than JPG and PNG. Lossy WebP can produce file sizes 25-34% smaller than JPG with equivalent quality, while lossless WebP is 26% smaller than PNG. It's now supported by all modern browsers.
• AVIF: A next-generation image format that offers even better compression than WebP. AVIF supports HDR, 10-bit images, and transparency. However, browser support is still limited.
• SVG: A vector format suitable for logos, icons, and graphics that need to be resized. SVG won't pixelate even when scaled many times over.
• GIF: An older format still used for simple animations. GIF is limited to 256 colors and is not suitable for photos.

How to Convert Between PNG and JPG

Converting images between PNG and JPG formats is very easy with the available tools. Here are several methods you can use:

1. Online converter: Websites like CloudConvert, Convertio, or FreeConvert allow you to convert images online without needing to install additional software.
2. Paint (Windows): Open the image in Paint, click File > Save As, and choose the desired format. Although simple, Paint doesn't offer many compression options.
3. Photoshop: For professional users, Photoshop provides full control over compression parameters and image quality.
4. GIMP: Free and open-source software that can convert images with various compression options.
5. Command line: Tools like ImageMagick allow batch conversion of many images at once using simple commands.

Keep in mind that converting from PNG to JPG will reduce image quality due to the lossy nature of JPG compression. Conversely, converting from JPG to PNG won't improve image quality because data lost during JPG compression cannot be recovered.

One of the biggest mistakes I ever made: converting all my JPG photos to PNG "to make the quality better." Believe me, for photos already captured in JPG format, converting to PNG won't improve the quality. Data lost during the initial JPG compression cannot be recovered. I learned this the hard way.

Conclusion: Which Should You Choose?

There is no format that is absolutely better than the other. The best choice depends on your specific needs:

• Use JPG for photos, images with many colors, web, social media, and when file size is a priority.
• Use PNG for logos, screenshots, web graphics, transparent images, text in images, and when quality is a priority.
• Consider WebP for websites as it offers the best compression of both formats.

The most important thing is to understand the characteristics of each format and use them according to context. With the right understanding, you can produce the best quality images while keeping file sizes optimal.

Want to learn more about other image formats? Visit our file extension database for complete information about the various image formats available.