When you use Masonry layouts for image-heavy grids, you often encounter unique challenges due to how images load in the browser. Unlike text or fixed-size elements, images do not have a fixed height until they are fully loaded. This means that when Masonry.js starts calculating the positions of grid items, it may not know the final height of each image. As a result, you can see layout shifts, where items overlap or leave unexpected gaps. Sometimes, the grid appears jumbled until all images finish loading.

This happens because browsers load images asynchronously. If Masonry.js initializes before every image has finished downloading, it arranges the grid based on the current—often incorrect—dimensions of each image. As images finish loading and their heights change, the grid items move, causing a poor user experience. Therefore, it is important for Masonry to wait until all images are fully loaded before calculating and applying the layout. Otherwise, you risk broken layouts, overlapping items, and content that jumps around on the page.