If you’ve ever shopped around for furniture, you’ll notice that they tend to come in a common range of sizes. Even amongst different manufacturers, they all have similarly sized dining tables, office desks, and nightstands. These “standard” sizes have become the default guide or baseline when designing a space. They offer predictability, helping ensure that furniture will generally fit within a space and coordinate with common seating and circulation standards.

But while these dimensions are helpful starting points, they aren’t rules. You don’t have to follow them exactly if they don’t fit your needs. In this article, we’ll explore these standards, when they work, and when they fall short.