How to read a Bangkok address — and why the driver still calls

A Bangkok address looks like a street address and behaves like a filing reference. The number is not a position on the street, the sois on one side of a road do not line up with the sois on the other, several of the most-used streets have a name instead of the number they officially carry, and the English spelling is a suggestion — one that the government itself does not apply consistently. None of this is disorder; it is a coherent system built on land registration rather than on walking down a street counting doors. Once you can read it, the puzzling parts of daily life here — the ride-hail driver who phones you, the delivery that goes to the wrong side of Sukhumvit — stop being mysterious.

The order, and the words

Thai addresses run from the smallest unit to the largest: house or building number, then the soi, then the road, then sub-district, district, province and postcode. Thailand Post publishes the standard through the Universal Postal Union, and it is worth knowing that the official specimen looks exactly as unfamiliar to a European eye as the one above.

Four Thai words do most of the work, and they are not interchangeable. Thanon (ถนน) is a main road. Soi (ซอย) is a side street branching off a thanon — usually numbered, sometimes named. Trok (ตรอก) is narrower still, an alley rather than a street, and the classic examples are in Chinatown. Yaek (แยก) is not a kind of street at all — it means an intersection, which is why you will meet junction names like Ha Yaek Lat Phrao, the Lat Phrao five-way. Mistaking a yaek for a soi will put you on a corner instead of a lane.

Then the administrative layer, where Bangkok deliberately uses its own vocabulary. Elsewhere in Thailand a sub-district is a tambon and a district is an amphoe; in Bangkok the same two levels are a khwaeng and a khet. Nothing else differs — it is a naming convention for the special administrative area, and Thailand Post’s own glossary sets out both pairs. Bangkok is divided into 50 khet, a number that has been stable since the city’s 1972 reorganisation and which we found no evidence of changing through 2026. The count of khwaeng beneath them is quoted inconsistently — the figures in circulation disagree and the ones with a clear date attached are old — so we would not memorise a number for that level.

One more word to disambiguate: muban (หมู่บ้าน), often written “moo ban”. Formally it is the administrative village that sits under a tambon and appears in rural addresses as a moo number. In everyday Bangkok usage it more often means a private housing estate. Both meanings are live, and which one you are looking at is usually obvious from whether there is a moo number in the address.

The slash: why 123/45 is not a street number

This is the piece that unlocks everything else. In 123/45, the first figure identifies the original land plot and the second identifies the building registered on that plot. The number therefore encodes when and on what land something was registered, not where it sits along the street. Everything that follows is a consequence:

• Numbers do not run in order along a soi. Walking up the lane looking for 88/17 by counting from 88/15 is a method that does not work, because the two may be nowhere near each other — or on opposite sides.
• New buildings get a suffix. A property built or subdivided later takes a “/1, /2…” after the fact, which is exactly why the sequence is broken.
• Two very different buildings can share a first number, because they share a plot of origin.

Practically, the consequence is that the house number is the last thing to navigate by and the first thing to write down. It is essential for post, deliveries and paperwork; it is close to useless for finding a door on foot. What actually locates you is the soi, and then a landmark within the soi.

Soi numbering: the staggered ladder

Along Sukhumvit Road, the most-referenced example in the city, odd-numbered sois branch off the north side and even-numbered sois off the south side. The important corollary is the one nobody tells you: the two sequences are staggered, not aligned. Soi 39 is not across the road from Soi 40. The odd side and the even side advance at different rates because the sois are different lengths and were absorbed at different times, so crossing the road to the next number is a reliable way to arrive somewhere else entirely. This is the single most common way a delivery or a meeting goes wrong on Sukhumvit — two people on the correct road, on the correct-looking number, several hundred metres apart.

We are deliberately not printing a specific “Soi X is opposite Soi Y” pair. The examples that circulate in guides contradict each other, and a reader with a map would catch it. The rule to carry is the shape of the thing: odd one side, even the other, never assume alignment.

How far does the odd/even convention generalise? It is well attested for Sukhumvit and holds on Silom, where the odd sois including Soi Lalai Sap sit on the southern side. For other arterials — Phahonyothin, Ratchadaphisek, Lat Phrao — we could find no properly sourced confirmation that the same parity rule is applied consistently. Treat it as a strong heuristic on the big Sukhumvit-style roads and not a law of the city.

Sub-sois, and the two things “39/1” can mean

Sub-soi naming has two distinct patterns, and conflating them causes real confusion:

• Insertion. A lane that appears between existing Soi 7 and Soi 9 becomes Soi 7/1, with 7/2 following if another appears. The slash here means “squeezed in after”, mirroring the logic of house numbers.
• Branching. A soi can have its own sois. Thong Lo Soi 4 is the fourth lane off Thong Lo — which is itself Sukhumvit Soi 55. The address nests.

So “Sukhumvit 39/1” and “Thong Lo Soi 4” are built by different rules, and the only safe reading is the one your map and your eyes agree on.

The famous sois are numbers in disguise

Several of the sois you will hear named every day carry an official number as well, and knowing both halves means you can match what a driver says to what a form wants.

Postcodes do not respect district lines

Thai postcodes are five digits, and the structure Thailand Post publishes is straightforward: the leading digits identify the province and the remainder identifies the post office. Bangkok shares its 10xxx provincial prefix with neighbouring Samut Prakan.

Because the second half tracks post offices, the tidy rule people assume — one district, one postcode — is false. Several Bangkok khet are split across two codes, among them Bueng Kum, Bang Khen, Lat Phrao and Prawet, with the boundary falling at khwaeng or even moo level. If a form rejects your postcode, the district is not necessarily wrong; the pairing may be. Thailand Post runs an official postcode lookup at thailandpost.co.th, which takes province, district and sub-district. Use that rather than an aggregator site — on this specific question the aggregators inherit the same one-per-district assumption that is wrong.

Why the spelling keeps changing

There is an official transliteration standard: the Royal Thai General System of Transcription (RTGS), published by the Royal Institute, with successive versions in 1932, 1939, 1968 and 1999. It appears on road signs and in government publications. It is also applied inconsistently — including by the state.

The cleanest demonstration we found is internal to the official record itself: Thailand Post’s own specimen address, published through the Universal Postal Union, spells a major road “Ratchadapisek”, while the transcription used on most maps and references is “Ratchadaphisek”. If the postal authority and the mapping convention differ on the same road in the same country, your search box does not stand much chance. The practical technique is to match on shape, not on letters: Thong Lo, Thong Lor and Thonglor are one place; Phetchaburi and Petchburi are one road name.

Decoding drill: what to do with what you are given

Most of the trouble comes not from a wrong address but from an incomplete one — a string that is perfectly clear to the Thai speaker who wrote it and ambiguous to you. Here is what the common shapes actually tell you, and what to do next.

Why the driver phones you

Put the pieces together and the daily experience explains itself. The house number does not locate a door. The soi may be long, with a single usable entrance from the main road. The English spelling in the app may not match the sign on the pole — there are documented cases of a lane known locally by one name and signed with an entirely different official one. Mapping data on smaller lanes and newer buildings is patchy. So the person driving towards you does the rational thing: they call, and they navigate by landmark.

Which tells you how to be findable. Give the soi and a landmark inside it rather than the house number: a BTS station and exit, a mall, a temple, a 7-Eleven, the name of the building. Drop the pin and then check what the pin says the address is — if it disagrees with your address, the pin is what the driver follows. Answer your phone; a number that rings out is a more common cause of failed arrival than a wrong address. And if you can, keep a copy of your address in Thai script to show or send, because that removes the transliteration problem in one step. The same discipline applies to anything delivered to you, and it is why a Grab pin often works better than a written address even though the address is more precise.

One thing genuinely helps on foot, and it follows from the geometry above: because sois are long and staggered, the distance between two adjacent-sounding addresses can be substantial, and the walk back out to the main road to cross is often longer than the walk in. That calculation is the same one behind deciding whether to walk at all.

One more document you will meet: the tabien baan

Sooner or later somebody asks about a tabien baan (ทะเบียนบ้าน), the house registration booklet issued by the district office, which records a property’s registered address and the people registered as living there. Two factual points are worth carrying: it is not proof of ownership — that is what a land title deed is for — and the address on it is the registered address, which is exactly the formal string discussed on this page and not necessarily what anyone uses to find the building. We are not going to go further than that here, because what a tabien baan means for any individual’s paperwork depends on their status, and that is a question for the district office rather than for us.

Quick answers

What does 123/45 mean?

Land plot, then the building registered on it. Not a street sequence — numbers along a soi are not in order.

Is Soi 39 opposite Soi 40?

No. Odd sois are on one side, even on the other, and the two are staggered.

Khwaeng or tambon?

Same level. Bangkok says khwaeng and khet; the rest of Thailand says tambon and amphoe.

Does each district have one postcode?

No — postcodes follow post offices. Bueng Kum, Bang Khen, Lat Phrao and Prawet each span two.

How do I make myself findable?

Soi plus a landmark, a dropped pin, the address in Thai script, and a phone you answer.