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PNG or JPG (JPEG) - which format to choose?

Every day browsing the Internet we deal with images, such as photos, diagrams and charts. It is very common that images are stored in a wrong format, being displayed in a bad quality and using more space than necessary. The question is: how to choose the right format? This article will attempt to answer this question.

The picture below shows a practical, simplified application of the PNG and JPG (JPEG) image formats.

png or jpg - which format to choose

Practical application of PNG and JPG (JPEG)

Based on the picture above, the choice is really simple - photos should be stored in JPG (JPEG) and illustrations should be stored in the PNG format. Following these guidelines you will always achieve the best image quality at the same time maintaining the smallest file size possible.

Now let’s see how these guidelines apply in practice. In the following experiments we will use a photo and a chart.

In the first example you can see a photo taken with a camera and stored in JPG. The photo was then converted from JPG into PNG.

photo in the JPG format

Photo stored in JPG format
has file size 100.6 KB

photo in the PNG format

Photo stored in PNG format
has file size 358.01 KB

The photo stored in PNG has a significantly bigger size - in this case, it’s more than 250% of the original. The size of the photo stored in PNG will always be bigger than of JPG. The main cause of this difference is the number of colours stored in each of the formats: PNG stores all colours, while JPG “assumes” that a human eye is not able to detect differences between very similar colours, so pixels with similar colours are grouped together and assigned the same colour. This makes JPG the best format for storing photos.

In the second example you can see a chart showing monthly average temperatures in Warsaw, stored both in JPG and PNG.

chart in the JPG format

Temperature chart stored in JPG format
has file size 36.65 KB

chart in the PNG format

Temperature chart stored in PNG format
has file size 22.74 KB

Storing the chart in the PNG format allows us to save a lot of space - in this case 63%.

Another advantage of PNG is that charts can achieve much higher quality, in comparison to JPG.

how JPG decreases chart quality

Noise introduced by JPG

The picture of a zoomed-in part of a chart stored in JPG presented above, shows that this format introduces a noticeable “noise” around high-contrast areas (around the borders and near the text). These disturbance is caused by the JPG compression algorithm attempting to adjoin similar colours (the average of black and white creates grey).

Considering the quality and the file size, PNG is the best choice for storing illustrations.

Whether you are a pupil, a student (creating charts), a worker (making diagrams and presentations), a parent (trying to save your children’s first drawings and taking photos), or an online auctioneer, I hope that you will find this information useful.

Polish version

FAQ: Frequently Asked Questions

Why convert image format / type at all?

Because you can pick the format that is right for the content, medium or platform where you use the images. For example, JPG images are generally better at storing digital photography than PNG. But PNG is better at storing vector graphics. WEBP is better for storing photos online.

Why convert image to PDF?

Sometimes you might want to print the documents, and your printer might work better with PDF files than images. That is especially useful when you deal with files containing vector graphics.

Why convert images to WEBP?

Website speed is an important factor when it comes to positioning of your website on the top of the search results. That’s why it is a good idea to use WEBP image format to store your photos for SEO sake. Such images have small file size but retain good quality when converted in comparison to PNG or JPG. And as a plus Google developed the format, which is why it looks favourably at websites that use it!

Why convert HEIC to other image formats (like JPG or PNG)?

HEIC is a great image for storing photos taken by iPhone, because it allows the photos to retain the “Live Photo” feature. But this is not the best format for exporting photos, especially to Android or Windows. That’s why it’s good to convert HEIC to JPG or PNG before sending them to mail or uploading them on a website.

How to convert PNG to JPG or JPG to PNG?

That’s actually quite simple using Simple Image Resizer | Image Converter. That’s because you just need to upload the photo in either JPG or PNG, select the output format and let the tool do it’s job. After that, all you need to do is click download now!

How to convert images on Mac or iOS?

Our tool let’s you convert images or photos on any platform (Mac, iOS, Windows, Android, Chromebook etc.). Just open Simple Image Resizer | Image Converter on your device and upload the photos you want to convert!

How to convert images to jpg on mobile?

It’s very simple, just open Image Converter on your mobile device and upload the images in whatever format you want. Then just select the format for output (JPG) and download the images.

How to convert HEIC to JPG or PNG on Windows PC, Mac, iOS or Android?

Simple Image Resizer | Image Converter Let’s you convert HEIC to either JPG or PNG. Just open the website on your desktop or mobile device, upload the HEIC file and select the output format. After our image converter finishes the job, you can download the image!

How to convert / change format from WEBP to JPG?

It’s quite simple, all you have to do is upload the WEBP file to our Image Converter and select the output file as JPG. Then wait for the conversion to happen and download the file!

How to convert TIFF to JPG?

It’s quite simple, all you have to do is upload the TIFF file to our Image Converter and select the output file as JPG. Then wait for the conversion to happen and download the file!