There are many factors to take into account when you're buying a custom mattress. What kind should you get? What brand? How firm should it be? What kind of budget is reasonable? Among this overwhelming amount of information, it's easy to miss the forest for the trees (or... miss the bed for the pillows?) and gloss over one of the most basic questions: what mattress size should you get? Resolving this question might seem as easy as knowing whether your bed will be sleeping one person or two, but it's not that simple. In fact, the array of options requires a thorough mattress size comparison to ensure that the bed you purchase fits your specific needs.

Before you head to the mattress retailer or online store, it's important to do a self-assessment of your mattress size needs. First, think about the sleep footprint you'll leave. Will the footprint include one body or two? Are those bodies small? Big? Tall? Short? A combination? Take note of the amount of space you, or your and your partner, will take up, and then add some extra space - nobody wants to be right up against the edge of the bed feeling like they're about to roll off. If the person sleeping in the bed tends to move a lot during sleep, you should add even more margin. Also, keep in mind that mattress measurements are slightly less than the standard bed size, to ensure the mattress fits inside the frame.

Once you've gotten a firm sense of your needs, it's time to consider the options. Here's our rundown on the different mattress size options and what each one is best for.

Twin Size

Size: 38" x 74"

Good for: Kids' bedrooms, smaller guest spaces, daybeds

Pros: Twin mattresses, also called single mattresses, take up the least amount of space of all beds, making them great if you want to maximize space in a small room. They're also the perfect choice for a child's bedroom and the only choice for bunk beds.

Cons: Twin size mattresses don't leave a lot of room for kids to grow into.

Twin Extra Long

Size: 38" x 80"

Good for: College dorm rooms, small apartments

Pros: Extra-long twins are perfect for teens or young adults who are too tall for their twin beds but don't need to upgrade width-wise. As narrow as a twin, they also take up minimal space, making them ideal for college dorm rooms or for apartments where you're looking to save space.

Cons: Though twin extra long beds add 6" space, they're no wider than a twin-size mattress, and can still feel a bit cramped for many adults.

Full Size

Size: 54" x 74"

Good for: Small guest rooms, single sleepers who need more space

Pros: About 40 years ago, when homes and rooms were smaller, full mattresses were commonly used for two adults. Today, they provide a good option for two smaller adults who don't have the room for a queen. With an extra 16" of width over a twin, they also allow a single sleeper to spread out comfortably.

Cons: At only 27" per person (the size of a crib), full mattresses are a tight fit for two. Plus, they're the same length as a twin, which can be too short for some.

Queen Size

Size: 60" x 80"

Good for: Couples, guest rooms

Pros: The most popular bed size, queens allow a comfortable amount of space for couples who don't have room for a king or split king size bed. They're also great if you're looking to maximize the amount of living space in the bedroom. For taller single sleepers who need a lot of space, it's a decent option as the smallest width bed size that's longer than a twin or full.

Cons: For couples with a bigger sleep footprint, queens have the potential to feel cramped.

King Size

Size: 76" x 80"

Good for: Master bedrooms

Pros: With an extra 16" of width (8" per person), kings provide couples a more luxurious sleeping experience than a queen. They are also ideal if either partner gets hot or moves a lot during the night, or if you have pets or children who like to climb into bed with you.

Cons: Significantly wider than a queen, king size mattresses require a large room.

California King

Size: 72" x 84"

Good for: Large master bedrooms

Pros: Great for extremely tall people that just cannot fit on any smaller mattress. All the roomy benefits of a king size bed, with even more legroom. A California king size bed should provide all the space you need for family, pets, and general lounging.

Cons: Space limitations might become a real issue with this mattresses' massive footprint. Careful measuring is in order before buying one of these beds.

Split King

Size: 76" x 80"

Good for: Couples with different sleep preferences

Pros: With dual adjustability, split king beds and split king mattresses are the solution for couples who have different sleep position preferences. If your partner likes a different level of firmness, or one of you is often sitting in bed while the other reclines or lies down, there's really no other option.

Cons: Split kings take up as much space as regular kings, and are generally more expensive.

 Of course, after you've considered all the options, be sure to go try a few out in-store, and, ideally, spend some nights sleeping on it before you commit. Some measurements and a description are often not enough to tell you if your sleep needs will be met—and beds are one thing where size really does matter.