How to Change Products Per Row in Shopify Warehouse Theme

Warehouse lets you set the grid density separately for desktop and mobile, so a layout that looks right on a laptop doesn't end up cramped on a phone.

Steps

In your Shopify admin, go to Online Store > Themes and click Customize on Warehouse.
Switch to a Collection template using the page picker.
Select the Product grid section.
Adjust Products per row on desktop and Products per row on mobile independently.
Click Save.

For a catalog-heavy store, a denser grid (four or five columns on desktop) tends to work better than it would on a lifestyle-focused theme, since shoppers browsing a large catalog are often scanning for a specific spec rather than lingering on individual product photography.