How long is a piece of string? There is no average monthly budget as you can spend a lot or very little in Chiang Mai and everything in between. Depending on where in Chiang Mai and how old/new the building is, you can still find a very basic 1bd for 3,000 baht a month, but you could easily spend
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k for a 2bd in a modern complex. Food the same - you can spend very little or a lot.