One of the first things that confuses visitors in Thailand is the address. Your hotel might say: Sukhumvit Soi 11. A restaurant is on Soi 38. Someone tells you to meet them in Soi 4. Google Maps shows another name entirely. Then you discover that the soi itself has smaller sois branching from it. Welcome to Thailand. The good news is that the system makes much more sense once you understand one word: Soi.
So What Is a Soi?
A soi is a smaller road, lane or side street branching from a larger road. The larger road is usually called a thanon. So: Thanon Sukhumvit = Sukhumvit Road. Sukhumvit Soi 11 = a side street connected with Sukhumvit Road. That basic idea solves most of the mystery. The Thai word “thanon” means road or street. Major roads in Bangkok include: Sukhumvit Road, silom Road, sathorn Road, rama IV Road, ratchadaphisek Road and phetchaburi Road. These are the main urban arteries. Sois branch away from them. This distinction matters. Sukhumvit Soi 11 is not exactly the same concept as “11th Street” in a North American grid. It is a branch from Sukhumvit Road identified by the number 11. That branch can be substantial. It may contain: Hotels, restaurants, condominiums, bars, shops, smaller lanes, apartment buildings and entire neighbourhoods. Some sois are almost roads in their own right.
At the other extreme, a soi can be little more than a narrow lane. Cars may barely fit. Motorbikes squeeze past. Houses line both sides. A food cart blocks half the road. A dog sleeps in the remaining half. Both this and a major commercial street can be called a soi. The word describes the relationship with the larger road more than the physical size. Sukhumvit is the easiest place for most visitors to learn the system. The main road runs through central Bangkok and continues far beyond the tourist districts. Along it are numbered sois. Sukhumvit Soi 4, soi 8, soi 11, soi 13, soi 21, soi 55 and many more. Once you understand the numbers, Sukhumvit becomes much easier to navigate. Along major stretches of Sukhumvit, odd-numbered sois are on one side of the road and even-numbered sois on the other.
This is extremely useful. If you are standing beside Soi 10 and looking for Soi 11, simply continuing along the same pavement will not get you there. You need the other side of Sukhumvit. The odd/even arrangement is a famous feature of the road.
But Do Not Turn It into a Law of Thailand
The odd/even pattern is useful in many places, especially major numbered roads such as Sukhumvit. It is not a universal rule that every soi in Thailand follows perfectly. Roads developed at different times. Naming systems vary. Some streets have names rather than numbers. Some layouts changed. Use the pattern as a navigation tool, not as a sacred law of urban planning. Sukhumvit Soi 11 is a good example of how misleading the word “lane” can sound. It contains large hotels, condominiums, restaurants and nightlife businesses. Thousands of visitors know the area by the soi number alone. “I'm staying on Soi 11” is enough information for many Bangkok residents to understand roughly where you mean. Sukhumvit Soi 4 is another globally recognised address. It is closely associated with the Nana area.
Again, the soi number has become almost a neighbourhood identity rather than merely an address component. Here Bangkok becomes more interesting. Sukhumvit Soi 21 is better known as Asok Montri Road. Most people simply say Asok. The road is large enough that calling it a tiny side lane would be absurd. Yet its relationship with Sukhumvit remains visible in the numbered addressing system. Sukhumvit Soi 55 is famously known as Thong Lo or Thonglor. Restaurants, bars, condominiums, Japanese businesses, cafés and nightlife. The street became one of Bangkok's major lifestyle districts. Most residents say Thonglor rather than Sukhumvit Soi 55. Both refer to the same major corridor. Sukhumvit Soi 63 is Ekkamai Road. Like Thonglor, it is a substantial urban road with its own businesses, residential areas and smaller branches. This shows the central principle: A soi does not have to remain small forever.
Bangkok can grow around it until the “side street” becomes a major road. This is why maps can appear inconsistent. One source says: Sukhumvit Soi 55. Another says: Thong Lo Road. A taxi driver says: Thonglor. They may all mean the same place. Thai roads often carry official names, traditional names, common names and numbered relationships simultaneously.
Spelling Adds Another Layer
Thong Lo, thonglor and thong Lor. All can appear in English. Thai script does not map perfectly onto Latin letters. Different romanisation habits produce different spellings. So sometimes the road is not changing. Only the English spelling is. Bangkok did not develop as a neat rectangular street grid. For centuries, waterways were more important than roads. Communities formed along the Chao Phraya River and canals. As roads expanded and land was developed, smaller access roads reached inward from larger routes. That produced long corridors and branching side streets rather than a simple grid. Old Bangkok was often organised around khlongs — canals. Boats moved people and goods. Homes faced waterways. Later road development was layered onto this older geography. Modern Bangkok therefore contains a street pattern partly shaped by a city that originally moved on water. As Bangkok expanded, plots of land were subdivided and developed.
Access roads pushed inward from major roads. Housing appeared along them. Then more development appeared behind the first layer. This helps explain why a soi may travel surprisingly far without connecting neatly to the next major road. One of the most important Bangkok lessons: Never assume a soi goes through. A road can look substantial. You walk ten minutes. It gets narrower. Then suddenly: Wall, canal, condominium gate and end. The next main road may be physically close but completely inaccessible. Bangkok reality says: 1.8 kilometres. This happens because direct geographic distance and usable street distance are different things. A canal, railway, gated property or dead-end lane may separate two places that look almost adjacent on a map. Long sois helped create the perfect environment for motorcycle taxis. A person gets off the BTS on a major road.
Their apartment is 1.5 kilometres down a narrow soi. Walking in 35-degree heat is unpleasant. A motorcycle taxi solves the final distance quickly. This is why orange-vested riders often wait at the mouth of busy sois.
The Mouth of the Soi
You may hear people refer to the beginning or mouth of a soi. In Thai, “pak soi” refers to the entrance area where the soi meets the larger road. This is a very useful concept. Shops, motorcycle taxis, convenience stores and transport often cluster around the pak soi. The opposite concept is being farther inside. A hotel may advertise itself as being “on Sukhumvit Soi 15”. That tells you surprisingly little about walking distance. Is it 50 metres from Sukhumvit? Or more than a kilometre inside? For hotel selection, this difference matters enormously. In Bangkok heat, 500 metres can become a philosophical question. If a hotel is deep in a soi, check whether it offers: A shuttle. Tuk-tuk service, motorbike taxi access, A nearby shortcut and or simply a reasonable walk. The soi number tells you location. It does not tell you convenience.
Now we reach the advanced level. A soi can have smaller lanes branching from it. Those branches may have their own numbers or names. So you can enter a soi and then enter another lane inside it. Thailand has effectively placed folders inside folders. You may encounter the word “yaek” in addresses. Yaek literally relates to a split, junction or branch. In address usage, it can identify a smaller branch within a soi. So an address can contain: Main road, soi, yaek and house number. At first glance this looks like someone designed the address as a practical joke. It is actually describing a hierarchy of roads. Think of it like a computer: Thailand → Bangkok → Watthana → Sukhumvit Road → Soi 11 → smaller branch → building Once you understand that hierarchy, the address stops looking random. Thai house numbers create another surprise.
Do not assume neighbouring buildings have consecutive numbers. House numbering can reflect registration history and land subdivision rather than simple walking order. You may pass number 25, then 25/7, then 33, then 27/4. This is normal enough that nobody waits for the universe to repair itself.
The Slash Number
Numbers such as: 42/1 42/7 99/23 often appear in Thai addresses. They can result from properties being subdivided or additional buildings being registered within an original numbered plot. The slash is therefore not the same thing as an apartment number by default. It belongs to the property address. Visitors from countries with extremely regular street numbering sometimes try. This can end badly. Use the building name. Map pin, Soi, Landmark and Phone number if appropriate. Thai addresses make more sense as location descriptions than as a perfectly sequential mathematical system. Thai directions frequently rely on landmarks. Near the temple, opposite the school, beside the 7-Eleven, behind the market and next to the petrol station. At the mouth of Soi 8. This remains useful even in the smartphone era because formal addresses do not always describe the easiest entrance. There is one flaw.
Thailand has a lot of 7-Elevens. “Meet me at the 7-Eleven” can be dangerously incomplete information. There may be three within walking distance. The experienced version is: “The 7-Eleven at the entrance to Soi 11.” Now we are getting somewhere. Outside dense central Bangkok, addresses may include “Moo”. Moo refers to a numbered village administrative grouping within a subdistrict. It is not the same thing as a soi. An address can therefore contain both a Moo number and a soi. Visitors normally do not need to memorise the administrative system unless they are sending mail, completing official forms or living in Thailand. Thailand also uses subdistrict-level administrative terms. Outside Bangkok, “tambon” is commonly used. Bangkok uses “khwaeng” for its subdistricts. These appear in formal addresses but are less important to most short-term visitors navigating by street. The next administrative layer differs too.
Outside Bangkok, districts are generally called amphoe. Bangkok uses khet. So a Bangkok address can contain a khwaeng and khet where a provincial address contains tambon and amphoe. This is bureaucratic geography, not another kind of soi.
The Postal Address
A formal Thai postal address generally moves from the specific property outward through increasingly larger administrative areas. You may see: House number. Moo or village, soi, road, subdistrict, district, province and postcode. Not every address contains every element. Urban and rural addresses can look quite different. Fortunately, you usually need much less. For a hotel in Bangkok: Hotel name. Soi or road. Map location. District or nearby BTS/MRT station. That is enough most of the time. Tell a Bangkok resident: “I'm near Nana BTS, Sukhumvit Soi 11.” They immediately have a useful mental map. Tell them the postcode. Much less useful socially. Postcodes matter to postal systems. Transit stations matter to humans moving through Bangkok. Another beginner mistake is seeing “Sukhumvit” in a hotel description and assuming everything is nearby.
Sukhumvit Road extends far beyond central Bangkok and continues as a major highway through eastern Thailand. “Sukhumvit area” without a soi or station can therefore be extremely vague. For Bangkok accommodation, the soi number can tell you much more. Soi 4 places you near Nana. Soi 11 is another familiar Nana-area corridor. Soi 21 means Asok. Soi 55 means Thonglor. Soi 63 means Ekkamai. Suddenly “Sukhumvit hotel” becomes geographically meaningful. Soi 10 and Soi 12 may be close. Soi 11 is across the road. But do not assume the numerical difference maps perfectly to equal physical distance. Side streets were not created according to one ideal geometric plan. Numbers help orientation. They are not a ruler. You may notice that some numbering sequences seem odd or that a soi has a name that dominates its number.
Urban history, road changes and naming practices can create apparent gaps. Do not assume your map is broken because the sequence is not perfectly elegant. Many sois have proper names. Some names are far more commonly used than their number. Others are known almost exclusively by the number. Some retain old local names. This is why asking a local can produce a different answer from Google Maps while both are correct.
Bangkok Is a City of Corridors
“Nana” itself demonstrates how neighbourhood language develops. Visitors use Nana to describe a general Sukhumvit area around Nana BTS and famous nearby streets. But addresses still rely on specific sois. Neighbourhood names and formal road names operate together. Asok works similarly. It can refer to the intersection area, BTS station, MRT connection and wider commercial neighbourhood. Sukhumvit Soi 21 / Asok Montri Road is part of that geography. The local shorthand is more useful than trying to reduce everything to one address line. Thonglor has become almost a brand. People say: Dinner in Thonglor. Nightlife in Thonglor. Condo in Thonglor. Yet the spine of the district remains Sukhumvit Soi 55. A numbered soi became a named neighbourhood. This is one reason Bangkok feels different from grid cities. Life concentrates along main roads and deep side corridors. A single soi can contain its own ecosystem. Laundry. Restaurant.
Apartment, massage shop, café, food stalls, school, convenience store, temple and motorcycle taxis. You can live surprisingly much of your daily life without leaving the soi. For residents, the soi can become part of identity. People know the vendors, security guards, motorbike riders, street dogs, restaurant owners and neighbours. A soi is not merely infrastructure. It can function as a small social world. Yes, Thailand has given international English vocabulary another phrase: “Soi dog.” It refers to street or community dogs commonly found around lanes and neighbourhoods. Many are tolerated or cared for informally by residents. Others may be genuinely stray. Treat unfamiliar dogs cautiously, especially at night. Some of Thailand's best food is found down ordinary sois. A restaurant does not need frontage on a giant boulevard. Local customers know where it is. Delivery apps know where it is. Google Maps knows where it is. The tourist who never leaves the main road misses a lot.
The Best Things Are Sometimes 200 Metres Inside
This is part of exploring Thailand. Main roads provide orientation. Sois contain detail. Walk inside and the city changes quickly. Traffic noise fades, residential life appears, small restaurants emerge, hotels hide behind trees and temples appear unexpectedly. Bangkok starts feeling less like one giant road. Exploration is good. Missing dinner because your “shortcut” ends at a wall is educational but less useful. Maps matter. Before smartphone mapping, visitors depended much more heavily on printed maps, taxi drivers, hotel staff and landmarks. Today the soi system is far easier for foreigners. Search the exact business. Follow the pin. Still, understanding the address helps when the GPS pin is imperfect or a driver asks which entrance you mean. A large property can have several entrances. A condominium pin may sit on the centre of the property rather than the driveway. A mall can face multiple roads.
A venue may technically belong to one soi while its practical entrance is from another. Always check the final hundred metres. For taxis, a famous landmark or main soi can be more useful than showing a long English address. If possible, have the destination in Thai. A map pin helps. A phone number can help if the driver needs to call the business. Do not assume every driver reads Romanised Thai place names easily. For short trips down a soi, motorcycle taxis can be extremely practical. Riders stationed at the entrance usually know local buildings well. A condominium name may be enough. The system exists because the local geography creates exactly this need. In cities such as Pattaya, local transport geography works differently. Songthaews may follow major routes while smaller sois provide access to hotels, bars, homes and businesses. The word soi remains useful even when the overall urban structure differs from Bangkok.
Soi Is a National Word, Not a Bangkok Word
Pattaya has famous numbered and named sois of its own. Visitors quickly learn that saying a soi number can identify an entire nightlife, accommodation or restaurant area. But Pattaya's numbering and road layout should not be assumed to work exactly like Sukhumvit. Different city, different history. Chiang Mai also uses sois, but the city's historic moat, old-city grid and ring roads create a different navigation experience. A soi remains a lane branching from a larger street. The larger city logic changes. Phuket addresses use sois across urban and resort areas. Patong, Phuket Town and beach communities each developed differently. Again, learn the word rather than memorising one universal numbering rule. Visitors associate sois strongly with Bangkok because Sukhumvit makes the concept famous. But the word is used throughout Thailand. Wherever roads branch into smaller lanes, you will encounter it. Because the distinction describes hierarchy.
Main road, side road and smaller branch. This tells you how the place fits into the surrounding network. The vocabulary carries geographic information. This is perhaps the easiest way to understand it. A Western address can feel like a coordinate. A Thai address often feels more like instructions through increasingly smaller spaces. Go to this district. Find this main road, enter this soi, find this branch and then locate this property. It is a hierarchy. So an address like: 99/12 Sukhumvit Soi 31, Sukhumvit Road, Khlong Tan Nuea, Watthana, Bangkok is not random. It is saying, in simplified terms: Property 99/12. Inside Sukhumvit Soi 31, off Sukhumvit Road, within Khlong Tan Nuea subdistrict, within Watthana district and Bangkok. Once you see the layers, it becomes logical. The soi system helps explain that too. Two major roads can run almost parallel while few smaller roads connect them. A pedestrian may need to return all the way to the main road. Cars and motorbikes dominate narrow lanes. Footpaths can disappear. Distance alone does not tell you walkability.
The Secret Shortcut
Some large sois effectively function as major streets and connect with other roads. These can provide important cross-city routes. Others remain dead ends. Experienced Bangkok residents learn which ones connect. That knowledge dramatically changes how the city feels. Bangkok residents accumulate shortcuts, through a small lane, across a canal bridge, behind a market, through a shopping complex and past a temple. The official road network is only one layer of pedestrian geography. Yes. The old water city still influences the modern road city. A canal can sit invisibly behind buildings until it suddenly blocks your route. Sometimes a tiny bridge crosses it. Sometimes there is no crossing for a long distance. Bangkok's history is still hiding inside your Google Maps walking time. A soi 800 metres deep may seem fine on a map. At 1 p.m. in April, it becomes something else entirely.
Heat and rain make transport access important. This is why hotel reviews mentioning “deep in the soi” deserve attention. Some hotels and condominiums offer small tuk-tuk or shuttle services to the main road. That is not merely a luxury. A deep-soi location can be inconvenient without one. The shuttle solves the geographic problem created by the road layout. For Thailand4U, we recommend checking four things: Which main road? Which soi? How deep inside the soi? Which BTS/MRT station or major transport point is actually closest? Those four questions are more useful than simply reading “central Bangkok” in a hotel description. Marketing departments have a flexible relationship with distance. “Near Nana BTS” might mean: Three minutes. Ten minutes. A fifteen-minute walk in tropical heat. Always check the map. Our destination guides use areas and neighbourhoods because a city name alone is often too broad. For Bangkok especially, soi-level geography can transform a recommendation. Sukhumvit is not one experience. Soi 11, asok, thonglor and ekkamai. Each creates a different visitor experience.
The Soi Tells a Story
A road number can reveal urban history. A small access lane becomes popular. Hotels arrive, restaurants arrive, condos arrive and property values rise. The soi becomes famous. Eventually its common name becomes more recognisable than its number. Bangkok grows from the inside out. Thonglor is the perfect example. Technically rooted in a numbered Sukhumvit soi. Culturally understood as an entire neighbourhood and lifestyle district. Urban language grows with the city. Many favourite Bangkok experiences happen in them. A hidden café, A tiny restaurant, A hotel entrance, street food, A neighbourhood bar, A local market, A massage shop and A quiet temple. The main roads get you across Bangkok. The sois are where much of Bangkok actually happens. Remember this: Thanon = main road. Soi = side road or lane branching from it. Pak soi = entrance to the soi. Yaek = a branch or split, sometimes used for smaller sub-lanes.
That vocabulary will solve most of the confusion. If your Bangkok address contains: Sukhumvit Soi 11 think: “Turn off Sukhumvit Road into branch number 11.” Done. You now understand more Bangkok geography than you did five minutes ago. Technically, it is a side street. Practically, it can be: A lane. A road, A neighbourhood, A food destination, A nightlife district, A residential community, A transport problem, A shortcut and A dead end. Sometimes all of them at once. Soi is one of those Thai words worth learning because English translation loses something. “Alley” sounds too small. “Street” sounds too independent. “Side road” is closer but still incomplete. A soi is a relationship between a smaller street and the larger road from which it grows. Once you understand that relationship, Thai cities become much easier to read.