Six-digit postal code system

Singapore Infopedia


The six-digit postal code system was introduced in Singapore in 1995.1 It was adopted by Singapore Post (SingPost) with the aim of facilitating the automation of mail processing, in particular the mail-sorting system.2

The postal code system currently used in Singapore is the six-digit code. It was introduced on 1 September 19953 to replace the previous four-digit code, which required 48 percent of mail to be sorted manually. With mail volume projected to increase six percent annually, SingPost saw the need for increased automation to raise postal standards and to reduce manpower.4

The new six-digit postal system enables mail to be sorted directly into the sequence of delivery for each postman, thereby reducing manual sorting to just 17 percent. However, manual sorting is still needed for incomplete addresses or if envelopes are flimsy or in odd sizes.5

The six-digit system enables the generation of one million numbers to cover the unique numbers of all delivery points in Singapore. The previous system, on the other hand, could generate numbers for only 10,000 delivery points. Each delivery point – a house, building or block of flats – is given its own identifying number. With the new expanded system, SingPost would be able to provide postal codes for future housing developments.6

Mechanism of the digits
Singapore first adopted a postal code system in 1950. The two-digit system then divided the island into 28 postal districts. This was replaced by the four-digit system in July 1979. The four-digit postal code system sub-divided the existing 28 districts into 80 postal sectors.7 The first two digits indicated the postal districts and the last two for the postal sectors.

The six-digit postal code consists of two parts: the last two digits (sector code) of the old four-digit postal code, followed by four new digits representing the delivery point within the sector. The delivery point is the residential block number (for Housing and Development Board flats), or the number assigned to a private house or commercial building. The latter number is assigned according to the alphabetical order of the street name in each sector.8

State-of-the-art sorting machine
Under the old system, mail was first sorted according to postal sectors. It was further sorted manually according to the postman’s beat within that sector. The postman then collected the mail for his beat and sorted it according to streets and apartment blocks, before arranging it in the sequence of delivery.9

In September 1998, the mail-sorting operations at Chai Chee moved to the Singapore Post Centre located along Eunos Road 8. The centre houses state-of-the-art mail sorting technology that was purpose-built for mail processing. The mechanised system automatically sorts mail based on the six-digit postal code and stacks the mail in order on trays for the postmen to collect. The new system allows more mail to be delivered in a shorter time.10

Preparation for the six-digit system

SingPost prepared the country for the transition to the new six-digit postal code system. It distributed the new postal code directory for free, and launched an easy-to-use automated, speech-enabled Postal Code Helpline system on 16 April 2002.11 New postal code information was also provided by automated machines. Organisations with large databases were given a free database conversion software to help convert old codes to the new ones.12

To mark the introduction of the six-digit postal code system, SingPost issued the Six Digit Postal Code commemorative collection in September 1995. It comprised two stamps: one with no value depicting the development of the postal code system, and the other on the six-digit postal code with a value of S$2.13

By end March 1997, the usage rate of the new six-digit postal code was about 85 percent of all mail delivered.14 This increased to 96.3 percent in March the following year.15 As at 31 March 1999, the usage level had reached 98 percent, an increase of 1.8 percent over the previous year. The high level of usage has allowed Singapore Post to reap the benefits of further automation at the Singapore Post Centre in Eunos.16


Joshua Chia

1. “Corporate Milestones,” Singapore Post Limited, last retrieved 1 June 2016.
2. “S’pore Telecom Explains Need for Six-Digit Postal Codes,” Business Times, 18 February 1992, 3. (From NewspaperSG)
3. Singapore Post Limited, “Corporate Milestones.”
4. “Need for Six-Digit Postal Codes.”
5. “Need for Six-Digit Postal Codes.”
6. “Need for Six-Digit Postal Codes.”
7. Eddie Koh, “Four-Digit Postal Code Makes Mail-Sorting Easier,” Singapore Monitor, 27 April 1983, 3. (From NewspaperSG)
8. Singapore Post Limited, “Corporate Milestones.”
9. “6-Digit Code to Save Time,” Straits Times, 15 February 1994, 19. Retrieved from NewspaperSG.
10. “Faster Mail Soon with New Sorter,” Straits Times, 12 September 1998, 31. (From NewspaperSG) “Corporate Information,” Singapore Post limited, last retrieved 1 June 2016.
11. Seng Li Peng, “SingPost Launches Speech-Enabled Helpline,” last updated 17 April 2002.
12. Kace Ong, “Software to Ease You into Six-Digit Postal Code,” Straits Times, 22 March 1994, 11. (From NewspaperSG)
13. “Two New Stamp Issues to Be Released on Sept 1,” Straits Times, 23 August 1995, 24; “New Collection of Stamps Sticks to Singapore’s Past.,” Straits Times, 5 December 1995, 5. (From NewspaperSG)
14. Singapore Post Pte. Ltd, Annual Report 1997 (Singapore: Singapore Post, 1997), 7. (Call no. RCLOS 383.495957 SPSPAR-[AR])
15. Singapore Post Pte. Ltd, Annual Report 1997/1998 (Singapore: Singapore Post, 1998), 8. (Call no. RCLOS 383.495957 SPSPAR-[AR])
16. Singapore Post Pte. Ltd, Annual Report 1998/1999 (Singapore: Singapore Post, 1999), 11. (Call no. RCLOS 383.495957 SPSPAR-[AR])

The information in this article is valid as at 13 July 2016 and correct as far as we are able to ascertain from our sources. It is not intended to be an exhaustive or complete history of the subject. Please contact the Library for further reading materials on the topic.


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