How to Reduce the File Size of a JPEG, Not its Dimensions!

Inevitably when referring to the size of a jpeg or photo, there is always some confusion. Does the 'size' refer to the file size of the photo (measured in megabytes or kilobytes) or the dimensions of the photo (usually measured in pixels)? In this article, I'll show you how to reduce the file size of a picture. 

The best online application for reducing the file size of a JPEG is tinyjpg.com.

Open Tinyjpg.com in your internet browser and drag-and-drop your photo or photos into the space provided. The application will optimise your images, reducing their file size without any noticeable change in quality. You can download your newly optimised photos individually or together in a zip file.

Drag and drop photo into tinyjpg dot com webpage

Drag & Drop Your Photo To TinyJPG.com

download compressed photo from tinyjpg dot com

When Complete Download Your Newly Optimised Photo

If you're worried about uploading your photos to the internet or prefer not to use an online tool, keep reading, and I'll show you step-by-step how you can reduce the file size of your photos on both a PC and Mac.

How To Reduce The File SIze of A Photo In Windows 10

Unfortunately, none of the applications that comes built into Windows 10 allows you to reduce the file size of an image without reducing its dimensions. Microsoft Word and Powerpoint have a picture compression feature, which works well, but it will also reduce the dimensions of the image.

This is not necessarily a bad thing. 

The photo I use in this tutorial is the one above, which I took in Riga using my iPhone X. The dimensions of the original picture are 4032 pixels by 3024 pixels. That's more than 4K resolution which is unnecessarily large for most situations and uses.

The file size of the image is a whopping 2.78 megabytes. Ideally, I would want to resize the dimensions of the photo to something more manageable while maintaining the photo's aspect ratio and without cropping. Having resized the photo to say,1080 pixels or Full HD, I would then look at reducing the file size through compression.

However, this article is about reducing the file size of a photo while maintaining its dimensions. So let's do that.

For Windows 10, I recommend downloading a free software called Image Compressor from the Microsoft Store.

How to install and use Image Compressor on Windows 10

If there isn't a link to the Microsoft Store app on your taskbar, you can search for it by typing, 'store'.

Once open, use the search bar and type, 'image compressor' and click on the magnifying glass. The search will return several results, most of which aren't free. It isn't necessary to pay for such a simple function, which is why I chose Image Compressor.

search for image compressor on the microsoft store

You'll find the Image Compressor app in the Microsoft Store

Click Get. Microsoft may require your account details to download and install the app. If you don't have a Microsoft account, creating one is straightforward and doesn't cost anything.

Once you've installed the app, you can launch it from the Store window or again use the Windows 10 search bar and type 'Compressor'.

image compressor on the microsoft store

Install and launch Image Compressor from the Microsoft Store

As you'll see, the app is very basic. The easiest way to use it is to drag and drop your photo or photos onto the window.

Drag and drop photo onto image compressor window

Drag and drop your photo onto the image compressor window

The photo will appear, as will a sliding scale in the bottom-left of the screen. Use this to reduce the file size. The original file size is shown on the right. It would be nice if the file size updated as you slide the scale to the left, but it doesn't.

use the sliding scale to reduce the file size of the photo

Use the sliding scale to reduce the file size of the photo

You must click on the icon that resembles an A4 page with its corner folded over to see the result. 

click on the A4 page icon to compress the photo

Click on the A4 page icon to compress the photo

The other two icons are to Save the current image and Save As, allowing you to rename the file. I would recommend using Save As and checking the results, rather than saving over the original.

That's it. In my example, you can see the compressed photo has maintained its enormous dimensions, but the file size of just 539 kilobytes; a saving of roughly 80 per cent.

My original photo file size versus the compressed photo file size

My original photo file size versus the compressed photo file size

How To Reduce The File Size of A Photo on an Apple Mac

Somethings are just infinitely easier on a Mac and reducing the file size of an image is one of them. All you need is the Preview app that is the default image viewer on Mac OS.

Open your photo in Preview, click on File in the menu and choose Export. 

export photo from preview on mac

Export photo from Preview on mac

Rename the file unless you wish to replace your original photo, set the format to JPG and use the slider to reduce the file size of the image. The file size will update as you move the slider.

In my example, I've slid the slider all the way to the left, opting for maximum compression to compare the results. Click Save to finish.

Set the export settings in Preview

Set the export settings in Preview

You can see in my example that the compressed image has a file size of 356 kilobytes compared to the original, which was 4.8 megabytes. The surprising thing is that, to my eye, there is very little difference in the quality of the two photos. Unfortunately, these screenshots don't do justice to either photo, since they have both been optimised for my website.

Compare the file size of the exported photo with the original

Compare the file size of the exported photo with the original

Final Thoughts...

Compressing a photo in this manner will always impact the image quality. However, it is possible to reduce the file size substantially before the change in quality becomes noticeable to the human eye. That said the resolution of photos, especially ones taken on the latest smartphones, tend to be needlessly large; more than most monitors or televisions are capable of displaying.

Before compressing your photos to reduce their size, it is worth reducing their dimensions, at least in line with the display you intend to view them on. You'll maintain the picture quality while reducing the file size.