Eastern Bluebird birdhouse dimensions & cut list

The exact entrance hole, floor size, depth, and mounting height for a Eastern Bluebird nest box — plus a cut-list generator for your lumber and a printable diagram.

Quick-answer dimensions

Entrance hole
1.5 in round
1 1/2" round (NABS standard). NABS also accepts a 1 3/8" x 2 1/4" vertical oval or a 1 9/16" round; do not enlarge beyond 1 9/16" or European Starlings can enter.
Hole height above floor
6 in
Floor (interior)
5.5 x 5.5 in
5 1/2 x 5 1/2 in (NestWatch). NABS accepts 4x4 in up to 5 1/2 x 5 1/2 in.
Interior depth
9 in
Interior height 9 in (NestWatch); entrance ~6 in above the floor (NABS: 4 1/2-6 in floor-to-hole).
Mounting height
4-6 ft
Habitat
Open grassy areas, fields, large lawns, orchards; low human/feeder traffic.

Cut-list generator

Printable dimension diagram

Front 5.5 in floor 1.5 in round 6 in Side 5.5 in deep 9 in

Placement & mounting

Mounting height4-6 ft
HabitatOpen grassy areas, fields, large lawns, orchards; low human/feeder traffic.
Placement notesFace the entrance east, toward open habitat (NestWatch). Space boxes ~300 ft (100 yd) apart; to reduce Tree Swallow competition, pair two boxes 15-20 ft apart. No perch.

Materials & cautions

Materials checklist

  • 3/4 in untreated cedar, cypress, or pine (one ~1x6 or 1x8 board, ~4 ft)
  • 1 1/4 in galvanized or exterior deck screws
  • Drill + 1 1/2 in spade/Forstner bit for the entrance
  • Recessed floor with ~1/4 in drainage gaps at the corners
  • Two ~1/4 in vent slots high on the sides

Cautions

  • No exterior perch (helps predators and invasive species).
  • Add roof overhang and recessed floor for rain; drill drainage holes.
  • Monitor weekly; remove House Sparrow nests (a non-native, unprotected species).
Sources & how the cut list is computed

The biological requirements above (entrance hole 1.5 in round, floor 5.5x5.5 in, interior depth 9 in, entrance 6 in above the floor, mounting 4-6 ft) are taken from the sources below and last reviewed 2026-06-18.

Data basis: NestWatch 'Right Bird, Right House' — Eastern Bluebird (1 1/2 in hole, 5 1/2 x 5 1/2 in floor, 9 in interior depth, 4-6 ft height, faces east, ~300 ft spacing), fetched 2026-06-18; entrance-hole options cross-checked with the North American Bluebird Society nest-box factsheet.

The interactive cut-list is DETERMINISTIC GEOMETRY, not an official plan. It assumes a simple back-mounted butt-joint box: the front and back panels overlap the two side panels (front/back width = interior floor width + 2x board thickness), the side panels fit between them (side run = interior floor depth), the floor sits inside (interior floor width x depth), and the roof overhangs. Heights come from the species cavity depth; a sloped roof makes the back panel taller than the front by the chosen slope. It is labeled a STARTING cut list; users should verify against the linked official plan and their own joinery.

Hobby-woodworking and backyard-habitat information only. Not wildlife-rescue, veterinary, or medical advice. Follow local regulations; for native cavity-nesters, monitor responsibly and control invasive House Sparrows and European Starlings per local guidance.

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