Cribs are the core of any nursery: They are large, expensive, and important to your baby's well-being, so don't guess when it comes to crib size. Read our guide to learn exact crib dimensions – so you can get it right the first time.

Standard Crib Size

A standard crib size is 51 3/8" – 52 5/8" L x 27 3/8" – 28 5/8". Standard cribs are traditional in both style and design. They are intended to comfortably fit your child during the first 18–24 months of their life. Although standard cribs can be on the expensive side, they are long-lasting, giving them a great value. Some standard cribs are even designed to transform into a toddler bed as your child grows. These convertible cribs typically include additional parts that help the crib transition into a new, larger sleeping space. The size of your nursery will affect the crib dimensions you choose. Due to their dimensions, standard cribs are optimal in larger rooms and spaces. They will thrive in open-layout nurseries or in the center of a spare room. For more tips on how to fit a standard crib in your space, check out our Baby Nursery Room Layouts guide.

Mini Crib Size

A mini crib size is 37 3/8" – 38 5/8" L x 23 3/8" – 24 5/8" W. Sometimes interchangeably known as portable cribs, mini cribs are an excellent alternative to the larger standard option. Their smaller size makes them great for tight or limited spaces. They are very lightweight, and some can be easily folded up, wheeled into a corner, or packed away for travel or other extended stays. Mini cribs are also more affordable. These are an excellent choice for homes without a separate nursery room or for nurseries that serve multiple purposes. Due to their smaller size, mini cribs won’t fit your child as long as a standard crib will. Monitor your child's growth to ensure that they can still comfortably stretch and sleep in the crib.

Crib Mattress Size

The standard crib mattress size is 52" L x 27" W. The mattress is typically 5" – 6" thick and should not be thicker than 6". For safety reasons, there should be no gaps larger than two fingers wide between the mattress and the crib. The typical mattress size for a mini crib is 38" L x 24" W. The thickness tends to be lower, around 3" – 4" high and no higher than 5". For more information on this, read our How to Pick the Right Crib Mattress Size guide.