How to Optimize Images Online – Image SEO Best Practices


In this text I address the question of how to optimize images online and suggest some image SEO best practices for a WordPress blog or site. This issue is frequently overlooked.

However there are many details related to the image SEO which, when taken together and when done properly, may considerably increase your chances for a good ranking.

Why you should read this text

I use a lot of images in my sites, and I have been in this for many years already. The picture below shows the media library in my biggest site, and as you see, it contains more than 8000 images.

Media library in one of my sites.
Media library in one of my sites.

So I guess I want to say that I have some experience with all this, and hopefully the text below will convince you that this is really so and that you will find it helpful.

Preparing the ground – an image example

Below I add an arbitrary test image, it will be used in the text to explain some SEO best practices:

This is AltTxt.
This is caption

Here is the code of this image, and at your side you can see such image codes  for your images when you switch to Text mode in your Edit Post back office. Such a code contains some useful pieces of information about the image that will be discussed further in the text:

Now we go, it may be a long read, so take a cup of coffee…

What is image SEO? How to optimize images for a website?

I am running WordPress sites, so the text here addresses images used for such sites only. I cannot say how much of this can be used for some other platforms because I have never used them.

So this is about optimizing images on your WP website for the following reasons: i) to help search engines easily understand what an image means, and also what the post is about, and ii) to potentially increase your chances for better ranking. Namely, bots practically do not see images, for them an image is a more or less empty space in your post. So it is advisable to do some necessary steps and to add relevant information.

There is quite a number of possible things to bear in mind and to do, so here are some:

  1. Optimize image file names.
  2. Use alt tags.
  3. Optimize image titles.
  4. Add image captions.
  5. An image should complement the text, so mention it in the nearby text what an image is about.
  6. Resize images.
  7. Make sure images are clear and attractive.
  8. Make sure you are using images legally, this is not about SEO, this is about avoiding trouble.

I shall address all these elements in the text below.

Are images important in SEO?

The short answer is yes, and this is due to several different reasons that will be discussed in the text. There are two different aspects here, i) images as seen by search engines, and ii) images as seen by readers. They are interrelated.

What are image keywords?

It is a common wisdom that every post should be focused on one particular keyword. Regardless of your or mine opinion about this issue, you can indeed use this targeted keyword in the parameters of a picture/image.

There are 4 places and elements of the image where you can use your targeted keyword, but this does not mean that you should use it in all these places. It is better to use its variant or synonyms, and tags. Therefore use the opportunity to increase your chances for better ranking and for more keywords. You can use the keyword at the following places:

  1. In the image title.
  2. In the image Alt Text (AltTxt).
  3. In the image file name.
  4. In the image caption.

1. Image title SEO and keywords. Does image title affect SEO?

Practical aspects of the image title regarding the SEO are as follows:

    • The title is not for machines, this is for your visitors. It shows when you hover over the image but this only if you have done it properly. This means if you have added it in the Image Title Attribute, the screenshot below shows where this is. This is from my test image given above.
Image Title Attribute.
Image Title Attribute.
  • If you have not used the targeted keyword elsewhere (image file name, Alt Text, figure caption), then use it here. Otherwise use something else. It can be call for action as well.
  • Instead of the targeted keyword you can use some synonyms or tags in Alt Text and image title, and make them different in these two places, this can only be beneficial.
  • Make it relevant to the text, and catchy, just as you would do with the post title.

The image title attribute doesn’t have any impact on keyword rankings because search engines don’t crawl them, so if you had to choose between optimizing Alt Text vs. titles, you should choose the former every time.

2. Image Alt Text SEO best practices

Alt Text is one of several details which you normally put into your picture. It is used in the following ways:

  • By search engine crawlers. Namely this is practically the only information which they might get about your image, together with the image file name. As mentioned, those search machines do not see the picture itself, but perhaps this statement might become obsolete soon as bots’ technology improves.
  • By people with visual handicaps, who also use help of some machines, screen readers. So in this case, obviously Alt Text is related to good user experience and Google will reward you if you provide an adequate information for your picture.
  • Sometimes images are turned off by users in case of a slow connection. They may be invisible even if readers do nothing, and this is when connection is slow. But the Alt Text will remain and the user will still have some extra information related to the missing image.

Some useful tips related to image Alt Text SEO:

  • Avoid keyword stuffing. If you have used the targeted keyword in the image file name or in the image title, then you will not use it in Alt Text.
  • Use some synonyms instead, some variant of the targeted keyword, some word from tags (if it is the matter of a post; nowadays pages in WordPress do not have tags). In other words, make it keyword reach without keyword stuffing.
  • Do not make a story here. Ideal number of words which Matt Cutts from Google recommends is 7, see the video below. Yes I know this is an old video, but this is still the same in Google.

3. Image file name SEO – How do I name my photos for SEO?

The image name is supposed to describe the image. But here are some rules to follow:

  • Make the name descriptive and relevant to the text and/or to the image.
  • Use dashes between the words. This helps machines to distinguish words, although Google is good at distinguishing them even without dashes. But why dashes? Well, Matt Cutts has repeatedly spoke about it, suggesting to use dashes (hyphens). This is an old video but I think it holds even now. This seems to be because Google used to treat hyphens as word separators, and underscores as part of the same word. For Yahoo dashes and underscores are both good.
  • Use the targeted keyword in the image file name if possible, similar to what you do in the post url. In fact, this is the best place.
  • Normally, readers do not see the image file name, but search engines do. But OK, let me correct myself. Readers can see the image file name if they know how to do this, here is how. If I right-click on my test image above, I shall have a menu offered so I choose Inspect.
This is what you get if you right-click on an image in a post.
This is what you get if you right-click on an image in a post.
  • Now click Inspect and it will show you the picture similar to the one below. Here you can see the image file name which is “How-to-Optimize-Images-Online-a-test-image”. So you see that I used my targeted keyword here with dashes, and added some extra info.
The code obtained from Inspect.
The code obtained from Inspect.
  • If you do not use the targeted keyword, then use some of tags which you would normally associate with the given post. Or use some variant of the keyword.
  • If you use the targeted keyword in the image file name, then do not use it in the Alt Text, image title, or in image description. This would be keyword stuffing.

4. Image caption for SEO – Do image captions help with SEO?

Do not miss to add description whenever possible. There are some claims on the Internet that they considerably decrease bounce rate. In other words, visitors tend to stay on the page if they see a caption under the picture.

I can not say with certainty that this is indeed so, but think always on ‘good user’s experience’. Google will reward you for this. As you can see in the screenshots above, I did not use my keyword in the caption.

What is the difference between caption and description in WordPress?

I always leave the image description box empty. The text that would be added there would only appear in image attachment page. This option you have when you add images, see the picture:

Attachment Page option.
Attachment Page option.

So instead of choosing this option, in Link To, I choose None. Though sometimes images may be in an image gallery with links so in such cases I choose Media File.

Such Attachment Pages are with a poor content (the one you added in the Description box) and having them many is not wise. All in all, the difference between the caption and description can be summarized as follows: always add a caption to an image, and leave the Description box empty.

The image size for SEO – Can images be bad for SEO?

The image size matters for SEO. There are two separate issues:

  • The actual size of the image within your text.
  • The storage space required for the image.

Regarding the actual size of the picture on the screen, use common sense, find a balance. See how other successful bloggers deal with it. Pictures describe a lot and they can replace many words, but this is all the matter of context. For Google spiders a picture is an empty space, remember this.

Remember, nobody has time to wait for your great huge picture to download. Make it smaller, ideally well below 100 kB. This is easily done by using some optimizers that are available on the Internet. So resize your image yourself. My test image above is only 25 kB, and it is 700 pixels wide. In fact, it may be too wide. Some claim that for mobile phones it should not be bigger than 600 pixels.

If you make a mistake by defining only height and width which will be visible on the screen, without actually re-sizing the image, when a user click on it, it will be downloaded first and the browser will then resize it after that. So you realize, this may be painfully slow. You will lose your visitor for sure.

Too many images per page/post may increase its load time, and this may be bad for SEO. But sometimes this cannot be avoided. Then try to make them small and do not forget to compress them.

Images and social media

In my another text, I described my experience with social media in general. This is indirectly related to the issue of images. By this I mean that you can have traffic from some social media platforms, and this will be registered by Google so the post’s ranking may be improved. In this context it is Pinterest to keep in mind because it operates with images only.

Pinterest works great for one of my sites as you realize from the screenshot below. So this is all about images and this is how it is relevant for this text.

My site's traffic sources.
My site’s traffic sources.

So this was all that I wanted to say on how to optimize images online in your sites and blogs. I hope you find this text useful. You might want also to read my text on how to add a pdf to a page or post.

If you are in search of a good site hosting and online business learning platform, you can use the same place where I started many years ago and where I am still now with my sites.

Thank you for reading. Let me know if you have questions, there is a comment box below.


8 thoughts on “How to Optimize Images Online – Image SEO Best Practices”

  1. wow what an amazing post!! thank you so much. I knew the importance of SEO for images but I had no idea about using dashes between the words.
    I always use keywords for all the visuals on my websites but never used dashes… does it matter much or can I leave it that way?

    • Thank you Sarah, kind words from you. Yes it is important to use dashes, I do not miss them ever.

  2. Your article is so much powerful and helpful especially for those who are struggling with SEO problem. You give a exact information which is really powerful and if anyone give a try of these tools that you mentioned then they will be see success and great result in their life. I really appreciate your work, we really lacking good information. Thank you for giving good information.

  3. Hello there!
    This was a very useful post. I had no idea that it is that important for images to be SEO friendly. I will follow your tips and optimize my images from now on and even do that with the images in my older posts. I can’t believe i haven’t done that earlier.
    Thank you so much for this helpful info!

    • Hi Katerina, thank you. You have seen some examples I gave, so obviously it is worth doing what you plan with your older pictures. Best luck.

  4. Hey,
    Thank you very much for teaching me more about image SEO practices 🙂

    I have been adding keywords to images within my posts, but I just didn’t know how effective it was until I started to search for images using my keywords within Google, and I was quite surprised by what I found.

    I will certainly be following your best practices from now on, as I move forward with my website images.

    Thank You!

    • Great to read your comment Neil. I myself have been making mistakes with images in the beginning, there are many details to take care about, and clearly it is worth doing this.


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