It’s pretty easy to buy alcohol in Thailand and throughout Bangkok. You can find easily beer (Chang, Singha, or Leo) in many convenience store such as 7eleven or Family mart, and you can find stronger alcohol like vodka or whiskey and wine at supermarket.
But be careful, as you can’t buy it throughout the day. The rule is really strict and you won’t be able to buy it, even at 3 minutes before or after the limit.
Basically, you can buy alcohol from 11am to 2pm and from 5pm until midnight. As mentioned earlier, most of the cashiers are automated and any alcohol won’t go through (i had to wait a few minutes to buy some once). The main reason for that is to avoid younger ones to drink after school.
Additionally, on some special days, it’s absolutely not possible to buy or order alcohol (anywhere). This happens mostly for buddhist ceremonies such as Makha Bucha (february), Visakha Bucha (may), Asalha Puja Day (july), Wan Khao Phansa (july). So be extra careful and stock some at home if you intend to drink on this particular days.
Outside of these particular days and time of the day, you can sip some delicious cocktails on a rooftop. Here’s the list of the best rooftops in Bangkok.