Last updated on April 12, 2026
The metric system was officially introduced by a law passed on 17 December 1923 as Measurements in Thailand. However, old Thai units are still in common use, especially for measurements in Thailand of land which is often quoted using the traditional Thai system of wha, ngaan and rai. In the provinces, old-times will occasionally use the traditional Thai system of weights and measurements. Here are some conversions:
| Thai system | Metric System |
| 1 square wha | 4 square meters |
| 1 ngan (100 square wha) | 400 square meters |
| 1 rai (4 ngan) (1 sq cen) | 1600 square meters |
| 1 baht | 15.16 grams |
| 1 tamlung (4 Baht) | 60 grams |
| 1 chang (20 tamlung) | 1.2 kg |
| 1 haap (50 chang) | 60 kg |
| 1 niu | 2 cm |
| 1 kheup (12 niu) | 25 cm |
| 1 sawk (2 kheup) | 50 cm |
| 1 waa (4 sawk) | 2 meters |
| 1 sen (20 waa) | 40 meters |
| 1 yoht (400 sen) | 16 km |
| 1 kwien | 2,000 liters |
| 1 ban | 1,000 liters (2 ban=1 kwien) |
| 1 sat | 20 liters (50 sat=1 ban) |
| 1 tannan | 1 liter (20 tannan=1 sat) |
Table of Contents
1. Traditional Measurements in Thailand
In the past, Thailand adhered to a system deeply rooted in age-old customs, a tradition that persists in rural regions or within specific industries. You see it often with title deeds in Thailand. This historical framework may still be evident today, offering a glimpse into the country’s rich cultural heritage and practices.
- Wa (วา): One wa equals 2 meters. It’s commonly used for measuring land. For instance, you might hear about a plot being so many wa wide.
- Ngan (งาน): One ngan is 400 square meters. Land measurements in Thailand often include ngan, especially when discussing property size.
- Rai (ไร่): One rai equals 1,600 square meters, or about 0.4 acres. It’s the standard unit for larger land areas, such as farmland.
2. Metric System
Thailand now uses the metric system for measurements, following global standards to stay consistent and compatible with international norms. It is used for:
- Length: Meters and kilometers are standard for distance.
- Weight: Grams and kilograms are used for weight. If you’re at a market, you’ll often buy fruits and vegetables by the kilogram.
- Volume: Liters and milliliters are the norm for liquids. Gas stations sell fuel by the liter, and you’ll buy bottled water in liters.
3. Everyday Measurements in Thailand
Throughout your daily routines, it’s common to come across a blend of various systems, each contributing its unique characteristics and functionalities to the overall landscape of your experiences.
- In Thailand, land and property are measured using traditional units such as rai, ngan, and wa, as well as square meters. Rai, ngan, and wa are commonly used units of measurement for real estate in Thailand. Additionally, square meters are also used to measure land and property in the country.
- Shopping: Grocery stores and markets use kilograms for produce and grams for smaller items like spices.
- Construction: Builders often use meters and centimeters for measurements but might refer to traditional units for land size.
4. Practical Tips about Measurements in Thailand
- Conversion: Familiarize yourself with basic conversions. For example, 1 wa equals 2 meters, 1 rai equals 1,600 square meters, and so on.
- Ask for Clarity: When in doubt, ask for measurements in the system you’re most comfortable with. Most locals are familiar with both and can help translate.
- Legal Documents: Ensure all legal documents, especially those related to property, clearly state measurements in both traditional and metric units to avoid any misunderstandings.
FAQS about Measurements in Thailand
How many square meters in 1 rai in Thailand (rai–ngan–square wah conversion)?
Thailand uses a traditional land system where 1 rai = 4 ngan and 1 ngan = 100 square wah (also written talang/tarang wah). A square wah is 2 m × 2 m = 4 m², so 1 ngan = 400 m² and 1 rai = 1,600 m². Quick formula: m² = (rai × 1,600) + (ngan × 400) + (square wah × 4). Example: 2–1–50 (rai–ngan–wah) = (2 × 1,600) + (1 × 400) + (50 × 4) = 3,800 m².
Rai to acres and hectares: what’s the fastest way to convert Thai land size?
For rough mental math, remember these anchors: 1 rai ≈ 0.395 acre, 1 acre ≈ 2.529 rai, and 1 hectare (ha) = 6.25 rai. Conversions: acres = rai × 0.395; rai = acres × 2.529; rai = hectares × 6.25; hectares = rai ÷ 6.25. Example: 5 rai ≈ 5 × 0.395 = 1.98 acres (about 0.80 ha). Or 1 acre ≈ 2 rai, 2 ngan, 11.7 sq wah (because 1 acre ≈ 4,046.86 m²).
What is a “square wah” (talang/tarang wah), and why is it on Thai title deeds?
A square wah (ตร.ว. / talang wah) is an area unit equal to 4 m². You’ll see it on Chanote and Nor Sor 3 Gor land title deeds and in property listings because it breaks plots into easy-to-read sizes (100 sq wah = 1 ngan; 400 sq wah = 1 rai). Memory tip: 25 square wah = 100 m², and 100 square wah = 400 m².
How are distances and speed limits shown in Thailand (metric vs imperial)?
Road distances and speed limits use the metric system: kilometers (km) and kilometers per hour (km/h). Highway markers (“kilometer stones”) and navigation apps display km, while fuel efficiency is typically in L/100 km or km/L. Imperial units are rare on roads, though you may still see inches used for things like TV screen sizes or pipe diameters in retail.
How are utilities billed—electricity, water, gas, and internet speeds?
Electricity bills charge per unit (kilowatt-hour, kWh), water is billed per cubic meter (m³), and cooking gas is sold either by kilogram (LPG cylinders) or by liter at service stations. Residential internet plans advertise speeds in Mbps/Gbps, and mobile data packages list GB allowances. If you’re budgeting a condo or house, check the kWh rate, monthly service fees, and any minimum charges per m³ of water.
Construction & real estate in Thailand: floor area vs land area explained
Land area is typically in rai–ngan–square wah, while building/floor area is in square meters (m²)—plans, BOQs, rebar sizes (mm), and ceiling heights all use metric. Listings sometimes mix them (e.g., “60 sq wah land with 180 m² usable area”). Air-conditioners are commonly sized in BTU (e.g., 12,000 BTU for a bedroom), while electrical loads and wiring remain in watts/amps/volts.
Everyday measurements expats ask about (temperature, fuel, food, gold)
Daily life is metric: °C for weather, kg/g for groceries, liter for fuel (including Gasohol E20/E85), and mL for drinks (330 mL cans, 500 mL bottles). Thai recipes often use ช้อนโต๊ะ (tablespoon ≈ 15 mL) and ช้อนชา (teaspoon ≈ 5 mL). In jewelry shops, Thai gold is sold by the baht weight, roughly ≈ 15.2 g per baht (a salung is a quarter baht, ≈ 3.8 g), while purity for Thai gold jewelry is commonly 96.5%.
Understanding the mix of traditional and metric systems in Thailand is key to navigating daily life and legal matters efficiently. Start by familiarizing yourself with the basic conversions, ask for clarity when needed, and ensure legal documents are precise. This knowledge will help you feel more confident and connected in your interactions and transactions in Thailand.
- Systems of Units Measurements Wikipedia