Google searches are about to look a lot different.

From Tuesday, the search giant will penalise companies whose websites are not geared for tablet and phone searches, in an algorithm update dubbed “Mobilegeddon”.

Companies with mobile-friendly sites will appear higher in Google rankings, while desktop-only sites are likely to be demoted beyond the first page of results, making them difficult to find.

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The update was a response to a shift in how internet users use the web, Google has said.

“As more people use mobile devices to access the internet, our algorithms have to adapt to these usage patterns,” a company representative wrote in a blog post.

While some companies may suffer in the short term, users will in fact “find it easier to get relevant, high quality search results that are optimised for their devices,” the blog said.

A Google graphic explaining the websites it will now favour in searches.

More than a third of Australian websites aren’t prepared for the algorithm update, despite three months of warnings, digital marketing experts Roi.com.au have found.

Large companies like Pepsi and Domino’s Pizza were yet to implement truly mobile-friendly sites, Roi.com.au reported.

Sixty per cent of Google’s traffic comes from mobile devices, Business Insider Australia has reported.

Despite garnering criticism for the move, a Google spokesperson said it had been working with website owners to help them with the transition.

“We’ve been offering resources for webmasters to test their mobile sites and tools to make their pages mobile-friendly,” the spokesperson told Fairfax.