Before You Start: Placement Rules

In Australia, Australia Post has guidelines for residential letterbox placement: accessible to the postie from the street, within 2 metres of the front property boundary, at a height suitable for delivery without the postie dismounting (typically 90–120cm from ground for walk-up delivery). Check your local council for any specific requirements. Your mailbox must display your house or unit number.

Installing a Post-Mount Letterbox

  1. 1

    Choose location and mark the post hole

    Select a spot within 2 metres of the front boundary, clearly visible from the street. Mark the centre of the post hole. Call Dial Before You Dig (1100 in Australia, free) before digging — underground utilities can be present even in front gardens.

  2. 2

    Dig a 60cm hole

    Use a post-hole digger or hand auger. A 100mm diameter hole is sufficient for a standard 75–100mm post. Depth of 60cm provides adequate stability for a letterbox post in most soil conditions.

  3. 3

    Set the post in concrete

    Place the post in the hole. Check it is plumb (vertical) using a spirit level. Pour in a dry-mix concrete product (like Postcrete — available from Bunnings, just add water in the hole). Add water as directed. Hold the post plumb while the concrete begins to set. Allow to cure for at least 24 hours before attaching the letterbox or applying any load.

  4. 4

    Attach the letterbox to the post

    Most post-mount letterboxes bolt to the top of the post through pre-drilled holes. Position the box at the correct height (90–120cm from ground to the opening), drill pilot holes if needed, and bolt firmly.

Installing a Wall-Mount Letterbox

  1. 5

    Mark mounting holes and identify the wall type

    Hold the letterbox against the wall in position. Mark the mounting hole positions. Determine the wall type: brick/masonry requires masonry drill bit and wall plugs; timber framing uses wood screws; rendered masonry same as brick.

  2. 6

    Drill and fix

    For masonry: drill with a masonry bit, insert wall plugs, drive screws. For timber: use appropriately rated exterior screws directly into the stud. Use stainless steel or galvanised fixings to prevent rust staining the wall.

Add your house numberAffix your house number clearly to the letterbox. Large, visible numbers (at least 75mm high) help emergency services, delivery drivers and visitors find your home. Reflective numbers are better in low-light conditions.

Frequently Asked Questions

Australia Post recommends a letterbox with a minimum opening of 230mm wide by 30mm high for standard letters, and ideally 340mm wide by 240mm deep internally to accommodate large envelopes and small parcels. Parcels that do not fit are left with a parcel pickup card. A larger internal capacity reduces missed deliveries significantly.
60cm is the minimum for a standard letterbox post in stable soil. In sandy or loose soil, go to 75cm. The rule of thumb is that one-third to one-half of the total post length should be below ground. A 1.5m total post with 60cm below ground provides a 90cm above-ground post height — suitable for most letterbox installations.