Yes, adding a built-in or custom closet generally increases your home's value and makes it more attractive to potential buyers. A well-designed closet adds utility, organization, and a touch of luxury, which are appealing selling points. Most homeowners see a return on investment (ROI) of 50% to 60%; for example, a custom closet can add about $1,000 to your home's value on average. The specific ROI depends on the type, with custom walk-in closets typically providing more value than reach-in closets. However, to maximize value, ensure the closet doesn't significantly detract from the room's usable square footage. Converting an entire room into a closet can actually lower your home's value. Similarly, using overly lavish materials may not recoup their cost. A good strategy is to add a closet that takes square footage from a non-living area, such as a garage, to create a mudroom closet.

The vertical space between closet shelves depends on what you're storing. For clothing like shirts and sweaters, 10 to 12 inches is enough. Towels and linens need 12 to 15 inches, while tall storage bins may require 18 inches or more. Overcrowding your shelves can reduce accessibility and increase clutter, so be sure to leave breathing room for your items.

Some features and upgrades you can add (some of which increase the closet’s value) are: modular shelving, motion-activated lighting, climate control, custom lighting, cigar humidors, revolving shoe racks, jewelry shelves, custom woodwork, and built-in laundry hampers. While only truly luxury closets have all of these, many custom closets have at least one special feature listed above. 

Walk-in closets are always the biggest and can easily be more than 100 square feet. Primary bedroom closets, even if not walk-ins, are the second largest category in most homes and sit between 30 and 80 square feet. Linen closets, utility closets, and built-in closets are smaller and, depending on their usage, tend to be between 10 and 50 square feet.