Bird House Dimensions

What Size Is Best for a Bird House?

Bird house
Caramel images / Getty Images

Cavity-nesting birds are flexible in their requirements for the preferred size of a bird house, but there is more than species preference at stack when planning the appropriate bird house dimensions. Whether you are building a bird house or choosing a new one to purchase, the right dimensions can make all the difference for safe, comfortable housing for your backyard birds.

Why Bird House Sizes Matter

Birds instinctively look for nesting cavities and bird houses that are the appropriate size for their needs, but what determines that best size?

A lot of factors affect how big a home birds need, including…

  • Adult Size: The bird house needs to be large enough to be comfortable for the brooding adults and still provide adequate circulation and ventilation. In addition to interior dimensions, the bird house entrance hole size needs to be able to accommodate the movements of the adults birds as they bring food back and forth to their mates and chicks. A house that is too tight can erode the adults' feathers and make them more vulnerable to predators and poor weather.
  • Brood Size: The more eggs a bird typically lays, the larger a base the bird house will need to accommodate each egg safely and comfortably, with room for the eggs to be rearranged if needed for proper incubation. Species that only lay a few eggs may use smaller houses, while birds that have larger broods will need houses with larger bases.
  • Fledgling Size: Altricial baby birds, such as most songbirds, can be nearly the size of adults by the time they leave the nest and will need a bigger house to accommodate their growth. Precocial birds, like cavity-nesting waterfowl, however, leave the nest much sooner and will not be as large, so a smaller house size can be acceptable.
  • Safety: The size of a bird house directly impacts how safe the house is for both the parents and their chicks. The house must be large enough to accommodate all its residents with proper ventilation for air circulation and temperature control, and the entrance must be positioned at an appropriate distance above the floor to safeguard against predator intrusion. At the same time, a house that is too large may not retain enough heat for healthy eggs and chicks, and a larger house could more easily admit bird house predators or other unwanted guests, and too much room will not help the chicks feel snug and secure.

    Planning the Best Bird House Dimensions

    When measuring a bird house for the proper dimensions, be sure to take into account the thickness of the walls, floor and ceiling. The dimensions for a safe, comfortable bird house are interior measurements, and improper measuring could subtract as much as two inches or more from the overall size of the house, making it much too small to be attractive and useful to the birds.

    See the table below for the proper interior base, overall interior height and entrance height measurements for the most common and desirable backyard birds that use bird houses. Measurements are given in inches.

    Beyond the Measurements

    While the right bird house measurements are essential, they are not the only factor that will encourage birds to use the house. When building or choosing a bird house, don't forget to consider…

    With proper measurements and careful consideration of what makes a house attractive to birds, it is possible to offer the perfect housing for your backyard birds to raise their families.

    Photo – Bird Houses © Walt Stoneburner

    Ideal Bird House Dimensions (Inches)

    Bird SpeciesFloor SpaceTotal House HeightEntrance Height Above Floor
    American Kestrel8x812-159-12
    Eastern / Western / Mountain
    Chickadees and Tits4x48-106-8
    Downy Woodpecker4x48-106-8
    Ash-Throated / Great Crested
    Hairy Woodpecker6x612-159-12
    House Finch6x664
    House Sparrow4x4 or 5x59-126-7
    Northern Flicker7x716-1814-16
    Red-Breasted / White-Breasted / Pygmy / Brown-Headed
    Pileated Woodpecker8x816-2412-20
    Prothonotary Warbler5x564-5
    Purple Martin6x661-2
    Red-Bellied Woodpecker6x612-1410-12
    Tree Swallow5x56-84-6
    Tufted Titmouse4x410-126-10
    Wood Duck10x1810-2412-16
    Bewick's / House / Carolina