Postcodes in Australia

Postcodes were introduced in Australia in 1967 by the Postmaster-General's Department (PMG) to replace earlier postal sorting systems, such as Melbourne's letter and number codes (e.g., N3, E5) and a similar system then used in rural and regional New South Wales. The introduction of the postcodes coincided with the introduction of a large-scale mechanical mail sorting system in Australia,[1] starting with the Sydney GPO.

By 1968, 75% of mail was using postcodes, and in the same year post office preferred-size envelopes were introduced,[1] which came to be referred to as “standard envelopes”.

Postcode squares were introduced in June 1990[2] to enable Australia Post to use optical character recognition (OCR) software in its mail sorting machines to automatically and more quickly sort mail by postcodes.

Australian postcodes consist of four digits,[3] and are written after the name of the city, suburb, or town, and the state or territory:

Recipient Name
100 Citizen Road
BLACKTOWN NSW 2148

When writing an address by hand, and a row of four boxes is pre-printed on the lower right-hand corner of an envelope, the postcode may be written in the boxes instead. When posting to an organisation, business names can be written instead of a recipient name. If an article is intended for a specific identity within an organisation, their identity can be prepended on the line above the business name, with c/- prepended to the business name.

If addressing a letter from outside Australia, the postcode is recorded before 'Australia', which is placed on a fourth line.

Australian postcodes are sorting information. They are often linked with one area (e.g. 6160 belongs only to Fremantle, Western Australia). Due to postcode rationalisation, they can be quite complex, especially in country areas (e.g. 2570 belongs to twenty-two towns and suburbs around Camden, New South Wales). The south-western Victoria 3221 postcode of the Geelong Mail Centre also includes twenty places around Geelong with very few people. This means that mail for these places is not fully sorted until it gets to Geelong. Some postcodes cover large populations (e.g., postcode 4350 serving some 100,000 people in Toowoomba and the surrounding area), while other postcodes have much smaller populations, even in urban areas. Australian postcodes range from 0200 for the Australian National University (now 2601) to 9944 for Cannonvale, Queensland.

Some towns and suburbs have two postcodes — one for street deliveries and another for post office boxes. For example, a street address in the Sydney suburb of Parramatta would be written like this:

Mr John Smith

99 George Street

PARRAMATTA NSW 2150

But mail sent to a PO Box in Parramatta would be addressed:

Mr John Smith

PO Box 99

PARRAMATTA NSW 2124

Many large businesses, government departments and other institutions receiving high volumes of mail had their own postcode as a Large Volume Receiver (LVR), e.g. the Royal Brisbane and Women's Hospital has the postcode 4029, the Australian National University had the postcode 0200. More postcode ranges were made available for LVRs in the 1990s. Australia Post has been progressively discontinuing the LVR programme since 2006.

Some places in Australia do not have postcodes. These are typically remote areas with little or no population.

Australia Post prefers envelopes sold in Australia to have four boxes in the bottom right corner of the front of the envelope. Entering the postcode in these boxes or squares, which Australia Post calls postcode squares, enables Australia Post to use optical character recognition software in its mail sorting machines to automatically and more quickly sort mail into postcodes, which also embeds routing information. Postcode squares were introduced in June 1990.[2]

Australia Post says that postcode squares should not be used for machine-addressed mail, or mail going overseas.

Many other organisations now use postcodes. Insurance companies often use postcodes when working out the cost of car and house insurance. Transport for NSW uses postcodes to give specific numbers for each bus stop in Greater Sydney. The stop number is five to seven numbers: the first four are the postcode, and the others show the bus stop (sometimes written with a space in between, e.g. "2000 108").

Many companies that produce metropolitan street maps also list the postcodes for each suburb, both in indexes and on the maps themselves. Spatial representation of postcodes is also very popular in defining sales and franchise territories.

Australian Bureau of Statistics, Australian Taxation Office and many other Federal and State government organisations publish a variety of statistics by postcode which extends the use Australia Post four digit code to many business and social planning related activities.

There is an inherent problem with spatial representation of postcodes since areas referenced to a specific postal code tend to change over time, as new postcodes are added or existing ones are split by Australia Post for operational purposes.[8]

Some mail generating software can automatically sort outward mail by postcode before it is generated. This pre-sort of mail into postcode order eliminates the need for it to be sorted manually or using mail sorting machines.

To improve mechanised sorting, each address now has a sorting number which is printed on the letter as an orange-coloured barcode. This number might be 12 digits long. This system enables the post office to place items in delivery order. Companies can also use Rapid Addressing Tool (RATS) to print Customer Addressed Barcodes, which are printed above the address. Every Delivery Point in Australia (DPID) has its own number. Barcode sorter machines sort and sequence letters up to C5 size. Flat multi-level OCR reads, imprints and sorts C5 to A3 sized articles.

• Postcodes in the United Kingdom - the United Kingdom equivalent
• Postal codes in New Zealand - the equivalent in New Zealand
• ZIP code - the United States equivalent

• Postcodes Australia - Australia Post's postcode search
• Australian Bureau of Statistics data related to postcodes
• Free Australia postcode maps by state and city
• Public domain database (XLS,CSV,XML,JSON) of Australia postcodes and geographical data