The Best Methods to Reduce Image Size and Increase Your Website Speed
In today's digital era, speed is everything, whether it is user engagement, ranking on search engines, or overall success of an online presence.
It's often the case that when looking at page weight, images make up the bulk of the problem.
Unoptimised images can dramatically slow down your site, which is really annoying for your visitors and could lose you business.
This guide is a technical one: the best ways to reduce image size and improve your website speed – so that you know how to deliver fast, lightweight, and beautiful-looking sites.
Why Website Speed Is Critical
But before we get into how to optimise images on your website, you need to know just how important site speed is in this day and age.
For starters, the user experience (UX) is the key.
Research demonstrates that 40% of people will leave a website if it takes 3 seconds or more to load.
Faster loading pages make users really happy, decrease your bounce rates, and keep users longer.
Google has implemented page loading into the SEO score of websites.
Google's Core Web Vitals algorithm likes websites that load fast.
The faster the site, the greater its likelihood of appearing in search results, and thus, the more organic traffic.
Third, you can drastically improve conversion rates by being fast.
Greater conversion: Up to 20% of online shopping cart abandonments are attributed to slow websites.
when e-commerce sites are faster, there are fewer cart abandonments and more completed sales.
The ever-increasing flood of mobile traffic finally brings another level of variability into the mix, in that more than 60% of people look at sites from smartphones and tablets, each with their own speed.
Photos are compressed and much smaller in size than on desktop, so they load quickly for users on slow Internet connections, or on 2G or 3G networks.
That’s because, when it comes to website performance, image optimization isn’t merely a technical ‘nice-to-have,’ it’s a business requirement.
Back to the Basics: What is Image Size, Resolution and Format?
Drawing inspiration from the video world, it’s important to distinguish between image size and image dimensions.
Image size refers to the file size or simply the size in KB or MB of an uploaded image.
This will also change the time it takes to download the image.
Image dimensions are width & height in pixels (e.g. 1920x1080).
One would naturally expect bigger file sizes for bigger dimensions: that is, there are more pixels to encode.
As far as the image formats, you would often run into JPEG, PNG, GIF, WebP, and SVG.
JPEG is ideal for photos or other images where some degree of detail loss is acceptable in order to achieve a much smaller file.
PNG is preferable for images requiring transparency or for crisp images with text & objects and images along with sharp edges.
It does not discard data, but in most cases it creates a larger file than JPEG.
The most widely used is the GIF, designed for simple animations that contain a small number of colors.
WebP is a new image format that was developed by Google as a response to the increasingly popular JPG and PNG image formats in particular.
Modern browsers support it more and more.
Use a perfect vector image format, wherever graphics are involved, be it logos, icons, or simple flat images.
When you're deciding to compress your images for the web, ensure that you make the proper format choice.
Best Ways to Reduce Image Size
• Selecting the Right Image Format
Selecting the right kind of image and finding the proper balance between quality and file size could make a difference in the performance of the images for their use case.
If your images have soft color tones and subtle textures, go with the JPEG.
So, really, it allows for a significantly reduced file size with some acceptable loss in quality.
When it comes to images with sharp lines, transparency, or some degree of text, like a logo or an icon, PNG is superior because it will also preserve quality losslessly.
If you’re looking for quality versus compression, WebP is the all-around best modern format.
Deliver WebP images to supported browsers to reduce the size of your files.
In the case of logos/basic graphic design, use SVG if you can. SVG scales infinitely, whereas with JPG/PNG, scaling increases the file size.
• Resize Images to Match Display Requirements
Big image/Small preview. One of the biggest mistakes is to upload big images that are scaled down to a very small size by the site.
For example, uploading a 4000x3000 photo to show it at 800x600 wastes both disk space and slows down the page.
This applies except for the ones that have the required size on your website.
Before uploading, we recommend that you resize your images to match the maximum display size that you need, i.e., the largest size that you need them to appear on your site.
You may have to use things like Adobe Photoshop, GIMP, and free services like ResizeImage.net or BulkResizePhotos.com.
Alternatively, you can do resizing on the server side with scripts/ImageMagick, or use CMS plug-ins which enable resizing images during upload.
Apply Compression the Smart Way
Compress a file, or make it smaller, by subtracting redundant or superfluous data.
Lossy compression can provide more substantial compression where some image data is lost – and it may not be really missed all that much.
Lossless compression reduces file size with no quality loss, making it a good choice for logos or when quality is crucial.
Popular tools include:
TinyPNG and TinyJPG, which provide smart lossy compression through easy web interfaces.
ImageOptim, a Mac application focused on lossless optimization.
Google’s Squoosh app, which lets you experiment with compression settings and formats.
Command-line utilities, like jpegoptim or pngquant for batch processing.
Use Lazy Loading for your site performance.
Lazy loading will wait to load the contents whenever they come into view as the user scrolls down, thereby decreasing the initial page size and load.
It helps minimize bandwidth particularly for the sites that host lots of images.
Enabling lazy loading with image tags in modern browsers can be done using the loading="lazy" attribute, as follows:
If you need a more universal solution or want extra functionality, you can use JS-library - Lozad.js or LazySizes.
Responsive Images: Deliver the Right Image Based on the Device
The size and resolution of monitors, however, vary, so serving the same huge image to all those users doesn’t really make sense.
You can state multiple sources for the same image using the HTML tag or the srcset attribute depending on the size, height, and pixel ratio of the device.
An example using srcset:
This way, mobile users will be receiving smaller images, less bandwidth will be used, and the website will load faster.
Apply Content Delivery Network (CDN) Image Optimization via the DomainRouteProvider.
CDNs provide your content from servers at multiple points around the world, and can therefore deliver it faster to people physically closer to one of those servers.
Some CDNs provide tools for automatic image optimization such as on-the-fly resizing, format conversion (JPEG to WebP), compression, etc.
For example, there are Cloudflare Images, Cloudinary, Imgix, and Akamai Image Manager.
Through the use of a CDN, and through having image optimization in place — much of the manual work is offloaded for you so your optimized images are served quickly.
For practical implementation, see our tutorial on Boost Website Speed with Cloudflare.
For small icons and UI elements use CSS sprites to combine images.
Small images such as icons or buttons can be combined into a single image file (a CSS sprite), which will reduce the amount of HTTP requests made to the server.
You can show the required portion of the sprite using the CSS background positioning.
This helps to reduce load time by minimizing the number of server requests, particularly on "legacy" browsers or low latency connections using HTTP/1.1.
Advanced Techniques for Image Optimization.
Automate Optimization into the Development Workflow.
To streamline your process, integrate image optimization into your development build tools.
Webpack provides image loaders for image optimization as part of the bundling process.
There are task runners such as Gulp and Grunt that have plugins like gulp-imagemin and grunt-contrib-imagemin which will optimize images on the fly.
This is to provide you with optimized images in your production builds with minimal human effort.
Use Vector Graphics Whenever Possible
It is a logo, icon, and simple drawing format on the web.
They are lightweight, resolution independent, and graceful when manipulated in CSS.
SVG files are super tiny and super sharp on high-DPI screens.
Cache Optimized Images
Ensure your web server uses strong HTTP caching headers to cache the images in the browser.
Static images should have very long expiry times, with cache-munging techniques, such as adding version hashes to filenames, to force the updated version to load when it changes.
Caching is what prevents users from having to download the same assets over and over whenever they return to the app.
Testing and Measuring the Impact
Once you have compressed your images, all you have to do is check your website speed with the help of these:
Google PageSpeed Insights, which measures performance and optimization opportunities around things like Largest Contentful Paint (LCP).
GTmetrix provides very detailed waterfall charts displaying the loading sequence and bottlenecks.
WebPageTest offers advanced testing from various geo-locations and devices.
Lighthouse is included in Chrome DevTools and helps developers audit the performance, accessibility, and SEO of sites.
Top KPIs to improve from a performance standpoint are going to be FCP First Contentful Paint, TBT Total Blocking Time, and overall page size.
Common Mistakes to Avoid
That is: over-optimising images to the point where they’re unattractive and of low-quality = bad user experience.
Not using responsive images, which are slow to download on mobile devices.
Uploading huge images without resizing, wasting bandwidth unnecessarily.
Failing to adopt modern image formats like WebP, missing opportunities for better compression.
Ignoring lazy loading, which forces all images to load immediately and slows page speed.
Conclusion
Image optimization and website speed are crucial elements in the current web development and website management.
But by carefully selecting image formats, sizing correctly and compressing well and using features like lazy loading and responsive images you can greatly enhance the performance of your website.
There are also CDNs to take advantage of, and you can go even further by automating the entire optimization process making certain your site remains fast and lean as it grows.
Websites that load faster not only offer a better user experience, but also rank higher on search engines, leading to better conversions and ultimately to success in a crowded online world.
Mastering image optimization is no longer optional — it’s a fundamental skill for developers, marketers, and website owners alike.
