In-article ads are responsive ads which means that they automatically adjust their size for the device that they’re being viewed on. On mobile devices in portrait mode, In-article ads expand to use the full-width of the user’s screen. The minimum width for an In-article ad is 250 px. The height of an In-article ad is automatically adjusted by AdSense.
To help increase revenue, Google In-article ad units automatically expand to use the full width of the user’s screen when their device is orientated vertically. In-article ads use high-quality advertiser ad elements so they look great and provide a better user experience for your readers.