Google’s John Mueller speaks on whether it’s okay to publish charts as images, or if it’s more beneficial to use HTML.
This topic came up during a Google Webmaster Central hangout held on July 24th.
A site owner asked Mueller what’s the best way to go about displaying charts with data on a web page.
Is it acceptable, in Google’s eyes, to publish the charts as images?
Or would there be some benefit to re-creating the charts in HTML?
Here’s what Mueller advises.
John Mueller’s Response
Mueller says there’s nothing wrong with publishing a chart as an image.
In fact, he outright recommends using images over creating charts with HTML code.
Relying on images to convey a message is a valid concern when it comes to Google crawling and understanding a page.
Site owners can ensure nothing gets lost in translation, so to speak, by utilizing the alt attribute.
“I think it depends a bit on what you want to achieve with the chart. Usually, these kind of things I would just add as an image and make sure that you have an understandable alt attribute for the image as well.
So if there’s any critical information in that chart that you need to get across then put it in the alt attributes. So that we can pick it up as text, so that people who can’t see the image can also get that information. But in general I would just use images.”
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Another way to communicate to Google what the chart is about is through adding textual content around the image.
To be sure, Mueller is not suggesting the site owner publish an image on a web page and leave it at that.
A web page containing just an image, with no text in the body of the page, is unlikely to gain much traction in search results.
Site owners can’t depend on image search results either, as Mueller says charts do not do particularly well in Google Images.
So a site owner’s best chances of publishing a chart that gets ranked in search results is to:
- Publish the chart as an image with an understandable alt attribute.
- Add sufficient textual content around the image to further explain what the chart is about.
“I think usually these kind of charts are not going to do something fantastic in image search, because it’s hard to image that someone is looking for that particular chart using Google Images. But, essentially, and image is the best approach there.
I don’t think you would get a lot of value out of making that chart into HTML and putting the numbers and labels into text, because that’s something that you could just as easily put in the body of the blog post or in the alt attribute as well.”
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Mueller didn’t add this part – but I would be remiss not to bring up the importance of page speed in a discussion about images.
When dealing with what could be some very large images, it’s important not to let file sizes get out of control.
With page speed being a ranking factor, you should vehemently avoid publishing bloated pages with images several megabytes in size.
The full question and answer can be seen below (starting at (0:32):