How to Compress images on Mac in 2023

🗓️ June 30, 2022 By ✍️ Jaysukh patel

We are all so fond of capturing every special moment of our lives, whether it’s going out and partying, a birthday celebration, or the beginning of a new event. We want to cover it all. But sometimes, our devices get filled with tons of pictures and screenshots. Pictures are the only things that consume most of the storage. But nobody wants to delete the digital memories that you have created.

So here arrives the question: Is there any way to keep your images secured and make some room for new ones? The answer is yes, and the solution to this problem is image compression.

If you are a Mac user, then this blog is for you. We have shared numerous options that you can choose from to compress your images, and you don’t have to fret about the quality of your files.

I hope, this blog post will help to all Apple’s Silicon M1-series, M1 Pro (MacBook Pro), M1 Max (MacBook Pro & Mac Studio), M1 ultra (Mac Studio), M2 chip of 2022 (MacBook Pro & MacBook Air) Or Intel chip Mac computer.

What is image compression, and how does it work?

If you ever look at two compressed and uncompressed images, you will hardly notice any difference between them at once. They may look similar at first, but when you check their image size, that’s when you will know the difference. Both of the images, the original one and the compressed one, will have different image sizes.

Image compression reduces an image file’s size without losing any information. It works by taking a large bitmap and breaking it down into smaller sections (called blocks). Each block contains data that can be used to recreate the original image but in a smaller space. The more blocks you have, the better your compression ratio will be.

Image compression is the process of reducing the size of an image by removing unnecessary information. In the early days, people used it to store pictures on floppy discs and later in digital cameras. It reduces the file size of images captured from digital cameras, webcams, and scanners. You can do image compression either by using lossless or lossy algorithms. Lossless algorithms cannot remove all data, but they do so with minimal degradation to the original image quality, while lossy algorithms cannot preserve all data but with maximum possible quality reduction.

Whereas the lossy algorithm is used to compress an image. You can apply it to any image, like text, sound, video, etc. 

The lossy algorithm reduces the data size without losing its high quality. Lossy algorithms are widely used in audio and video compression and multimedia applications.

Is it possible to compress images without visible quality loss?

As mentioned in the upper section, there are two ways to compress an image; they are lossless and lossy algorithms. Lossy compression results in the loss of the original quality of the picture. It affects the pixels of the image. The more minor the files get, the more noticeable the changes will be.

Lossless compression helps retain the information and find a better way to store it, which results in maintaining the quality of the image. So the result of your reduction largely depends on the type of method you are using.

How to reduce the photo size on Mac?

If you are running out of space on your Mac because of the stock of images with higher resolution or want to attach some files over the mail, but the size is creating an issue, then reduce the photo sizes.

 And you can easily do that in just a few steps. 

Step 1: Select the image you wish to reduce the size.

Step 2: Right-click it and select Quick Options, followed by Convert Options.

Step 3: It will open a whole new window, where you can select the format from JPEG, PNG, and PNG.

Step 4: Next, in the image size drop-down menu, select Small, Medium, Large, and Actual and hit Convert to JPEG.

Your new File with a reduced size will be saved in the exact location as the original File. And the sweetest thing is that you can do this same thing with multiple pictures. 

How to compress images with the Mac Preview app?

One of the superb things about the Mac is that it allows compressing photos without purchasing other photo editing software. Its built-in app called Preview can do that. 

Follow these simple steps:

Step 1: Go to the application folder, look for Preview, and open it.

Step 2: Choose an image that you wish to compress. Drag the image into the Preview located at the bottom of your deck. 

Step 3: Then, on the menu bar, go to Tools and click on the Adjust Size option.

This will show you a pop-up window where you must look for a few things.

First, you will get a resulting size box at the bottom showing the actual size of your File. 

Then, in the image dimension, select the pixels option.

Step 4: On the top list, you will get an option to fit into. What you need to do is to select a dimension available that is smaller than the current dimension of the image.

Step 5: After checking the image size and selecting your preferences, click “OK.”

Step 6: Next up, go to view, which is available on the menu bar, and scroll down to the actual size. What it does is it precisely shows us the real dimension of the image on the screen. 

Step 7: When you’re finished, Go to File and hit Duplicate because you do not want to overwrite the original File. 

Step 8: Finally, go to File, rename your File, choose a location to save it, and click Save.

If you want to differentiate between the original and compressed image size, go to the folder where you have recently saved your photo and check the details of it.

How to compress images with online tools? [Useful for Mac & Windows users]

Thanks to the bunch of image compressor tools available online, you do not always have to rely on Mac Preview and other software such as Photoshop. Here is the list of the top three that you can go for to compress your image in no time.


This website is at the top of the list of online image compressors because you have the freedom to select between lossy and lossless compression. You can use this website with large image files with a higher resolution. Some features include free 50 compressions of files up to 10 M.B. per day. Another advanced part that makes this website great is adjusting the compression ratio to get even further size reduction.

Now let’s look at the steps to using it.

Step 1: In your browser or Safari, go to

Step 2: Choose the compressed image file and then drag and drop it from your computer.

Step 3: Wait for some time and click on “Download” once the compression is done.

2. TinyJPG:

If you have to compress images of a smaller size, that is, 5 M.B, and you also have a bulk of them, then you can try this website. The attractive user interface has a panda on it. TinyJPG runs on a lossy compression algorithm to reduce the file size of the images. This website allows the user to compress 20 JPEGs and PNGs at once, whose size limit must be 5 M.B. There’s no daily limit on this website, so you can add as many files as you wish to, even in the free version. The paid version gives you the feature of adding files of up to 75 M.B.

To perform the compression on this website, follow these steps:

Step 1: Go to and open the website.

Step 2: Click “drag your files here” and select the File you wish to compress.

Step 3: Allow the File to upload. Once done, it will display how much of the File is compressed.

Step 4: You can directly download it by clicking on the “download all” option or save it to your Dropbox.

3. Optimizilla:

When you already have two options available to do most of your work, why go for another one? Well, the answer is that this website has no daily limits or size limits. But you can only add 20 files at once. Optimizilla is an intelligent online image compression tool that works on the lossy algorithm to reduce the image size of JPEG, GIF, and PNG images without compromising the image quality.

Using this website is way more leisurely; follow these steps:

Step 1: Open the website on your browser by simply typing

Step 2: Click on “Upload Files,” which will direct you to your file location. Select the images that you want to compress.

Step 3: You now have two options: either download all of your files if you uploaded multiples or simply click on the individual ones to download them separately.

Step 4: Choose your option and click on “download.”

What are the free ways to compress images on a Mac?

Freeing up space to add more files or to attach them over e-mail, whatever might be the reason, if you want to compress the images on your Mac, here are a few easy and free ways to do it.

  • Change the format to reduce the image size: Most of the screenshots taken on an iPhone or Mac are saved in PNG format if that image contains text only. If the screenshot has graphics, it will be kept in JPEG format. To reduce the image size of the files, you can change the format from PNG to JPEG, which will not affect the quality.

Change The Format Of The Screenshot On Your Mac Using Terminal:

The Terminal is a program that can be used to access the command line on Mac OS X. It comes pre-installed with Mac OS X.

Hit COMMAND+SPACE on your keyboard. It will open the spotlight where you can easily search for Terminal. Click on it, and it will open up a new window. 

Next up, you must paste a set of lines into the Terminal Window and hit the Run key to execute the command and change your files into different formats. 

To change into JPEG format:  Use the following line to transform it into JPEG format:

killall SystemUIServer; type jpg;

To change into GIF format: Use the following line to transform it into JPEG format:

Write com. apple.screencapture type gif; killall SystemUIServer by default.

To change into PDF format:  Use the following line to transform it into PDF format:

killall SystemUIServer; type PDF;

To change into PNG format: Use the following line to transform it into PDF format:

killall SystemUIServer type png

To change into TIFF format: Use the following line to transform it into TIFF format:

killall SystemUIServer type tiff

Compressed Images In bulk using the Preview Application

Follow these simple steps, and you can compress several images at once using only the default Mac Application Preview. 

Step 1: Open the folder containing the images you want to compress.

Step 2: Select all the images and hit right-click> Open with > Preview App (Default).

Step 3: A new preview window will open up containing all the selected images, and it will be displayed on the left side. Select one image and hit Command+A, which will select all the files.

Step 4: After selecting everything, go to the Tool option on the Menu Bar and select Adjust Size.

Step 5: This will open a window where you can select the various size dimensions. Select one of them.

Step 6: Lastly, click on OK, and the changes will be applied to all of your files.


From using the default application on Mac named Preview to the online website available we have shared every possible way you can use to compress the size of your image and that too with retaining the quality of it. Hope this article has been helpful for you and will save your time and effort. Keep visiting our website for such tech-related blogs. Thank you for reading.

Jaysukh Patel
Jaysukh Patel

Jaysukh Patel is the founder of howtoisolve. Also self Professional Developer, Techno lover mainly for iPhone, iPad, iPod Touch and iOS, Jaysukh is one of responsible person in his family. Contact On: [OR]

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