WHY OPTIMISE IMAGES?
There are three important reasons to optimise images for websites (not print media).
- To help images and therefore a path to your web page, to be found well by search engines.
- Page load speed is an IMPORTANT search engine ranking signal. The need for speed became more important for SEO because:
- Google’s search ranking algorithm started taking user experience (UX) into consideration in the summer 2021. User experience has indirectly affected page rank for some time. We’ve all been frustrated with the gradual loading of a photo dumped from a 25-megapixel camera straight onto a webpage without SEO consideration for both the photo file name and photo file large data size.
- You should not inflict expensive mobile data download costs on users if images are NOT optimised. This is especially true for places like Africa and Pacific islands, where internet data is expensive.
- For your image to show as a thumbnail in Google SERPs it’s best to be at least 1200 pixels wide with an aspect ratio of 16:9 or 4:3, or 1:1.
Visual search infographic links to more image optimisation for SEO stats.
My Perth Pinterest.
HOW TO BEST OPTIMISE IMAGES FOR ISO (Image Search Optimisation)?
There are many ways to optimise images, either before or after adding them to your website.
- Give images a file name that relates to the most important pages which the image will be added.
- Use keywords in image file names and image alt tags that accurately describe to blind people what the image is about.
- With computer graphics software, crop your image to one of three aspect ratios mentioned in point 3 above.
The above HTML is an example bad image use in a web page.
- poor photo file names
- wrong aspect ratio
- missing image alt tags
- wrong file type (not next generation)
Optimise Images BEFORE Adding to Web Pages
IMAGE PHYSICAL SIZE
Feature/header/hero images need to be wide to show on big desktop screens. I tend to go for a maximum of 1920 pixels wide images for web page header images. Minimum is 1,200 pixels.
Think about the average width of mobile phones. There are so many makes and models of mobile devices. For most of my images, I tend to use 768 pixels wide because it’ll fit on most tablets without pixellating.
Why does WordPress scale (resize) images?
WordPress scales images by default to improve website performance and user experience, generating multiple sizes, such as thumbnails and medium versions, from each uploaded image. This ensures images are displayed at the most appropriate dimensions for various locations on your site and different devices. There’s no point in trying to load a 1920 pixel wide image on a 800 pixel wide phone. Additionally, a feature introduced in WordPress 5.3 automatically scales down images larger than a 2560-pixel threshold to be “web-ready” and therefore avoids slow load times and increased server space.
What default sizes does WordPress scale images to
WordPress scales uploaded images to several default sizes, including Thumbnail (150x150px), Medium (300x300px max), Medium Large (768px wide), Large (1024x1024px max), and Full Size (the original uploaded dimensions)
What are recommended image sizes for web pages?
Recommended image sizes for WordPress websites in ratios of 1×1 or 4×3 or 16:9. Eg 768×768 px or 768×432 px or 1200×675 or 1024x576px. I like the 16:9 aspect ratio of HD TVs. 16 divided by 9 = 1.7777777777, a good number to remember. Eg if an image is 1440 wide then dividing its width by 1.777777777 give you a height of 810 pixels.
What is the best image size for Google Business Profile posts?
Google Business Profile is a big free kick for you from Google. According to Google’s guidelines, the recommended image size for posts in GBP is 720x720px
IMAGE PROPERTIES
Cloud-based image optimisation, such as tinypng.com, strips metadata from images. If you want to add image metadata back after optimisation, read on.
How to add image metadata using MS Windows.
- Locate your image in Windows File Explorer
- Right-click it > Properties >
- Give it a title and description with keywords. Eg below:
Image optimisation property details for SEO for the do and don’t image below.
IMAGE DATA SIZE
Compressing the DATA size of images before uploading can be done with Tinyjpg.com, Optimizilla, Kraken, CompressNow, GiftOfSpeed, etc. Tinyjpg.com has an option to convert to the Google-invented next-generation format of .webp before downloading.
What is the best size and aspect ratio for thumbnail images in Google SERPs?
To optimise an image to show on the RHS of Google SERPs, the image width should not be less than 1200px and no bigger than 150 KB. Google SERPs used to crop an image into a square but nowadays I sometimes see rectangles in SERPs.
Below is a thumbnail image in Google AI Overview results of me lecturing Action business coaches about SEO at the Mount Lawley Golf Club.
For best results, provide me with multiple images with the following aspect ratios: 16×9, 4×3, and 1×1.
If you want thumbnails to show in Google SERP and to avoid losing bits of image left and right margins, it’s better to publish an optimised SQUARE version of your image on your web page. Eg:
.
Optimising Images AFTER Adding to Web Pages
If you use a good WordPress image optimisation plugin, it will use thumbnails of various preset image sizes, detect the device, (eg table) used for seeing images and then serve up the best size image for the device.
Good WordPress image optimisation plugins will convert jpg formated images and serve them up as highly compressed webp formats. I use the EWWW image optimiser. All except my basic price SEO plans include a paid version of EWWW, which EWWW claim to load images 5 times faster.
What is a good image optimisation WordPress plugin?
You can configure WordPress image optimisation plugins to either losslessly compress for better quality or lossy-compress images for even more speed and slightly less quality. As an SEO specialist, I go for less quality in preference for faster loading images which can account for over half the page load speed time. You can adjust the quality of lossy images. Configure image optimisation plugins to save in next-generation image formats such as .webp. Also, test site wide lazy loading images.
IMAGE OPTIMISATION TIPS FOR SEO
USE RELEVANT IMAGES
- Your images should be relevant to your web page content.
- Irrelevant images will diminish the quality of your webpage content, thus reducing its SERP ranking.
- How can you get relevant images?
- Take photos yourself.
- Search free online image library.
- Use a copyright free photo that is more than 70yo.
- Buy an image from an online dealer.
- Use Ai to generate an image
IMAGES IN SITEMAP
Ensure images are included in your site map to make it easy for search engines to crawl images. If using WordPress try the Google XML Sitemap plugin if you’re not using, for example, the Yoast sitemap.
WHAT IS THE BEST IMAGE FORMAT FOR SEO?
- Choose the best image format for SEO.
- Next generation webp format is best for colour photos or gradients/shading. If you don’t want to use webp then jpg (.JPEG) is the next best option.
- png is better for solid colours and transparency
- I don’t recommend an animated gif but if you insist, keep it small and simple. You can search for and use pre-created gifs from online gif libraries or you can create them using Giffy or good computer graphic design software.
WHY USE IMAGE ALT TAGS?
Image alt tags started as a description for visually impaired people. 19% of searches on Google returned image/s. If you want your images as an attraction and visitor path to your sales information and or brand then use image alt tags.
Use alt image tags for good SEO and increased accessibility.
Incorporate focus keywords in image alt tags but avoid keyword stuffing.
MULTIPLE IMAGES
It’s lazy/easy for web designers to keep uploading the same image with different file names to your WordPress media library but that is an SEO issue because it forces web browsers to download a different image file each time instead of referring to one cached image in your computer. If you are a web designer designing for my Perth clients, do NOT upload multiple copies of the same image:
Author: Ben Grummels, SEO expert, influencer, Perth, Australia.