How to Reduce Image File Size

Have you ever had one of those great photos that you wanted to share or upload only to find out there was a file size restriction? Your grand photo was too big. Professional photographers and designers know how to get around these barriers, but this can be a nightmare for others. Fortunately, some easy and free online picture optimization services can reduce image file size without sacrificing quality.

Part of the file size problem is that digital cameras on our phones are getting better. This means the picture can be huge in both pixels and file size (MB). Recently, one viewer wanted to upload her images to a photo contest, but the site restricted the file size to 5MB per image. She wanted to know how to reduce the photo file size so she could submit her entries.

3 Methods to Reduce Image Sizes

Most problems have multiple solutions. In remembering my reader’s inquiry here are three solutions:

  1. Reduce the image dimensions. For example, if the original image was 4000px x 2000px you could reduce it to 2000px x 1000px. You probably want to keep the same aspect ratio. Many image programs like SnagIt or Affinity have this option to redefine the image by percentages or number of pixels.
  2. Photo cropping – this works well if you have non-relevant objects you can cut from your image.
  3. Use an image compression routine to remove extra data, including EXIF data.

Certainly, many software packages can do the above steps. However, they often come with a steep learning curve or expense. If you go that route, I much prefer Affinity Photo.

However, you can use one of the free image compression websites. The results will be a much smaller photo image file but at the same dimensions. This process is also useful if you need to reduce Microsoft Word file sizes.

My Ideal Solution

When looking at these services, I had some requirements in mind.

  1. Cost – I was looking for free services
  2. Ease of use
  3. Privacy and ownership
  4. Overall Features
  5. Ample file upload size
  6. Image file formats – I was concentrating on JPG

In many cases, this info was on the website. However, there were some services that didn’t address these issues.

How I Tested

I bought a stock image (JPEG) that weighed in at 9629KB to test the image optimization services. My math was based on the original file size and resulting file size. In some cases, online services showed different values.

This is also a reminder that you shouldn’t rename your compressed images the same name as your original. Always keep your original pictures as you may want to test various services. Another reason is some file formats such as JPG get very grainy when you try to enlarge them.

Test photo.
Test Photo © Patryk Kosmider

The original photograph, in the red outline, was 4500 px X 3000 px. Once I finished testing, I opened Snagit and Affinity Photo to see if I could notice visual differences between the files. From my perspective, the original and compressed images looked the same. I didn’t see any washed-out colors. All the services did allow you to compare “before” and “after” images.


JPEGIO image and results.
JPEG.IO Results

What I liked about JPEG.IO was the simple design. Although I was focusing on JPG images, I was surprised to see many supported image file formats, including WebP. It also allowed you to import images from 3rd party storage services like Dropbox, Google Drive, and Box. Although you can’t see the full image until you download the file, I could see a thumbnail image when I hovered over the button or clicked Download File.

What I disliked was that there was very little information about the site and service. I could see a lone pop-up dialog, which told me the service used proprietary technology.

Kraken.IO is well-known for image compression and tools. I’ve used their paid services in the past with great success to optimize images for this website. From the domain registration, I thought the same company might own JPEG.IO. However, I never got a response to my email inquiry.

The service did reduce the picture from 9.6mb down to 3.56mb (37% of the original). The version looked just as good as the original.

Final Image size: 3561 KB / 37% of original.


Optimizilla picture and results.
Optimizilla Results

Optmizilla didn’t seem as polished, but I learned it is feature-rich. They clearly state the JPG or PNG files you upload will delete in 1 hour. Two items stood out. The first was they offer 14 different language options other than English, which I thought was a nice touch.

They also allowed me to use a slider to adjust the image quality. This is something you might see in desktop software. I didn’t see this feature offered with the other web applications.

The output examples of the before and after images weren’t as large as other services and contain an inset. I’m guessing when the initial thumbnail loads, it’s using the center of your image. You can click the image and locate a more important part of the photo for comparison.

The service reduced the file size the most bringing it down to 20.1% of the original size. As with the other services, the compressed image looked fine to me.

Final Image size: 1931 KB / 20% of original.


Compressor.IO Results

Compressor.IO is a personal project of front-end developer Stephane Lyver and uses open-source software such as OptiPNG, JPEGOptim, etc. The service did an impressive job at image compression. The resulting photo was reduced to 24% of the original size. According to the site, it’s possible to get a 90% file reduction. It can optimize JPEG, PNG, SVG, GIF, and WebP.

The service allows 3 options for compression: Lossy, Lossless, and Custom. If you drill down into the custom option, you see additional options such as resizing the image and fine-tuning the image quality. However, these options are not available on the free version.

Final Image size: 1326 KB / 13.7% of original.


Squoosh is a new player on the block from Google Chrome Labs. Like Compressor.IO, it includes many image file formats, including some beta versions. It’s the only service I’ve seen that handles the newer AVIF format.

Like the other services, the process begins by uploading your file. The initial pass will convert using the same file format. However, you can do additional edits with other file formats. Using a JPEG XL (Beta) option, I could get the best compression, which was 4% more efficient than the default pass.

What’s also appealing is the options that show after the first pass. You can also reduce the number of colors via a Reduce palette option and even resize. The only drawbacks I saw were there is no help, and I encountered processing errors with AVIF.

The service also looks out for developers and allows you to copy NPX commands or clone the repo from GitHub. You can install install a desktop app if you prefer.

Squoosh optimization options

Final Image size: 1495 KB / 15.5% of original.

Multiple Winners

I think all these services did what they claimed, and I would feel comfortable using any of them. If I had to provide a starting point, I would opt for Squoosh. I think it provides the most options, which could be handy if you need to fine-tune your settings.

It’s also interesting to note that when I first conducted this image compression test in 2017, Compressor IO came in at 2,135KB and is now the leanest file size.

Directory listing of compressed images and sizes.
Original Image and Compressed File Sizes

One item to remember is that these file size reduction results can vary based on the image. I only used 1 image in this test and not a set containing varying colors, sizes, and resolutions. As the saying goes, “your mileage may differ.”