Birdhouse & Hole Size Calculator
Get the perfect dimensions for your feathered friends.
Building a birdhouse is a rewarding way to attract wildlife to your yard. But to attract specific birds and keep them safe, dimensions matter! A correctly sized entrance hole, interior floor, and height can deter predators and invasive species while providing a comfortable nesting space for your target birds. Use this calculator to get the ideal plans.
Plans for the
Entrance Diameter
Floor Size
Interior Height
Predator Guard
Why These Dimensions Matter
- Entrance Hole: This is the most critical measurement. It’s designed to be just large enough for the target species, while being too small for larger, more aggressive birds (like starlings) and common predators.
- Floor Size: Provides the right amount of space for the typical number of eggs and hatchlings (the clutch size) for the species. Too large, and the nest may not stay warm; too small, and it becomes overcrowded.
- Interior Height: The distance from the floor to the bottom of the entrance hole is vital for safety. A deeper box prevents predators like raccoons from reaching in and grabbing eggs or young birds.
Important Construction Tips
- Material Matters: Use untreated wood like cedar, pine, or cypress. Never use pressure-treated wood.
- No Perches: Avoid adding a perch below the entrance hole. Native birds don’t need them, and they provide a foothold for predators.
- Ventilation & Drainage: Drill a few 1/4-inch holes in the floor for drainage and add gaps at the top of the side walls for air circulation.
- Rough Interior: The inside walls should be rough or have grooves cut into them to help young birds climb out when they are ready to fledge.
- Placement is Key: Mount your birdhouse on a pole or post. Face the entrance away from prevailing winds (typically east).
Annual Maintenance Checklist
- Clean Out After Nesting: Once you are certain the nest is empty (usually by late summer or fall), remove all old nesting material. This reduces parasite problems for the next season.
- Scrub and Dry: Use a solution of one part bleach to nine parts water to scrub the interior. Rinse thoroughly and allow the box to dry completely in the sun before closing it up.
- Inspect and Repair: Check for any damage, loose screws, or enlarged entrance holes. Make necessary repairs to ensure the box is safe and secure for the next year.
- Store or Leave Up: You can store the clean birdhouse in a shed or garage, or leave it mounted. Some birds may use it for roosting during cold winter nights.