Apple would like you to go big: The company introduced a new maxi-sized iPad, dubbed the iPad Pro, at its press event in San Francisco this week. Apple CEO Tim Cook called the device “the most capable and powerful iPad we’ve ever created.” That may be true — but with its 12.9 inch screen, it’s also clearly the biggest one. In fact, the iPad Pro’s screen is twice the size of the iPad mini.

So why is Apple now selling a giant iPad? The answer is simple: You can blame your phone for it.

When Apple first introduced the iPad in 2010, its 9.7 inch touchscreen seemed huge in comparison to the then-current iPhone 4, which had a screen size of 3.5 inches. But phones have grown massively in size ever since.

Samsung pushed the envelope early on when it introduced the Galaxy Note with its 5.3 inch screen in 2011, and it followed up with a 5.7 inch model in 2013. Other Android phone manufacturers followed suit with giant screens, including Google with its 6-inch-sized Nexus 6 and HTC with a 5.9 inch One Max. Companies like Huawei and Hisense have even introduced phones with screens measuring up to seven inches in recent months.

Apple long resisted the push for bigger phones, but the company had to eventually give in to market demands, and introduced a 5.5 inch iPhone 6 Plus last year, followed by this year’s 6s Plus with the same screen size.

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But phones with big screens haven’t just replaced smaller smart phones, they have also eaten into the sales of tablets. Android tablets, a product category that was never really able to match the success of the iPad, were the first to feel the crunch. Samsung shipped 11 million tablets during last year’s holiday quarter, according to IDC, compared to 13.5 million the year before. Amazon’s Android-based Kindle Fire tablets even saw shipments decline by close to 70 percent during the same quarters.

But Apple hasn’t been immune to this trend either. Sales of the iPad were down 18 percent during the company’s most recent quarter, while phone sales were up 35 percent.

The trend away from tablets and to phones isn’t just about screen size. It’s also an indicator of how much more powerful phones have become, and how big of a role they are playing in our daily lives. Phones are now our default photo and video camera, they’re how we consume media and they integrate with everything from wearables to car dashboards.

Tablets on the other hand haven’t shown any big leaps in innovation, and largely still fulfill the same functions in their owner’s lives as they did two, three or even five years ago. That’s why Apple is now trying to redefine what a tablet can do and be. The company is hoping that targeting professionals, and the enterprise, will help to capture new markets for the device category.

Many have rightfully pointed out that Apple has taken quite a few cues from Microsoft for the iPad Pro, down to the external keyboard that doubles as a case. That’s because in order to compete with the iPad, Microsoft tried to position its Surface tablets not as media consumption devices, but as tools to create and get work done.

Apple is now doing the same thing — except this time, it’s about competing with today’s smart phones.