The Thai Baht, Thailand's Currency

Banknotes come in five denominations, each with its own color, ฿20 (green), ฿50 (blue), ฿100 (red), ฿500 (purple), and ฿1,000 (brown/gray). All carry the image of the King, which matters in practice, because Thai law treats defacing or stepping on money as an insult to the monarchy, so never stamp on a dropped note to stop it blowing away.

Coins run ฿1, ฿2, ฿5, and ฿10, plus 25- and 50-satang pieces you'll mostly meet as supermarket change. The workhorses of daily spending are ฿20s, ฿100s, and ฿10 coins. ATMs dispense ฿1,000s, so break them at 7-Elevens, supermarkets, or malls early and hoard the small stuff for street food and transport.

Budget ฿1,000–2,000 ($30–60) per person per day in cash for the things that are cash-only (street food, markets, tuk-tuks, songthaews, laundry, temple entry) and put hotels, malls, chain restaurants and tours on a card. For a week that's ฿10,000–15,000 in baht, and you don't need to land with all of it. ฿2,000–3,000 exchanged at the airport covers the taxi and first meal, and city exchange booths or ATMs give better rates than anything you'll get at home.

Two official numbers to know. Immigration can ask arriving visitors to show funds, ฿10,000 per person (฿20,000 per family) on a visa exemption, ฿20,000 (฿40,000 per family) on a tourist visa. Checks are rare, but the rule specifies cash or equivalent foreign currency. Separately, you can bring up to US$20,000 (or the equivalent) into Thailand without declaring it. Above that, or above ฿500,000 in baht, you must declare it at customs. Neither is a reason to carry your whole trip budget in cash. Bring a few days' worth, then use a no-fee travel card at ATMs.

The best rates in the country come from dedicated exchange chains, SuperRich (the green and orange ones), Vasu, and SIA Money Exchange in Bangkok. They routinely beat banks by 1–2% and airport counters by 3–5%. Bring clean, undamaged notes, since torn or heavily-worn foreign bills are refused, and US $100 bills often get a slightly better rate than small denominations.

Don't exchange at home before you fly. US and European banks give worse THB rates than you'll get in Thailand. Exchange ฿2,000–3,000 worth at the airport for the taxi and first meal, then do your real exchanging in the city. Hotels are the worst rates of all, and airport counters are second-worst.

The zero-exchange alternative most travelers land on is to pay by card where possible and pull baht from ATMs with a no-fee travel card (Wise, Revolut, Schwab). Even after the ฿220 machine fee, a ฿25,000 withdrawal costs under 1% all-in. That's competitive with the best cash rates, and you're not carrying thousands of dollars through airports.

Visa and Mastercard work at hotels, malls, chain restaurants, supermarkets, and most tour operators. American Express is patchier. Thailand's own QR payment system (PromptPay) is everywhere, but it needs a Thai bank account, so as a visitor you'll watch locals scan while you pay cash. Contactless acceptance is growing fast in Bangkok. Assume nothing outside the cities.

Tipping is appreciated but not expected, so round up taxi fares, leave ฿20–50 at casual restaurants, 5–10% at nicer ones if no service charge is already added (check the bill, many add 10%), and ฿50–100 per day for hotel housekeeping or a helpful driver. Nobody will chase you for a tip, and nobody refuses one either.