With no official data of what central Bangkok property investors can expect to achieve on average, the best source of useful data could well be from Numbeo.com.
This website collates crowdsourced data from users around the world, and for cities from around the world.
For central Bangkok, rental yield data for the past six years makes interesting reading.
It shows that average rental yields being currently achieved right now are generally low compared with those being achieved in 2014 and 2015.
That said, rental yields in central Bangkok now and good compared with other cities in Southeast Asia. In Singapore, for example, investors are getting 2.67 percent on average, according to the website.
Central Bangkok rental yields
Some Thailand developers, often keen to attract first-time buyers and investors, and more so outside Bangkok, are starting to offer guaranteed returns. Promotions offering 8 percent for five years are not uncommon, but the question anyone should ask is what rate should be expected following the expiry of the guarantee period.
A drop to just three percent may play havoc with investor balance sheets.
Real estate agents can be a good source of average rental yields that are currently being achieved in Bangkok, but perhaps only in areas they are personally familiar with.
Some property portals also offer data based on asking prices of listed properties. They can also give a good indication, but for us, crowdsourced information is probably the best source of accurate information for central Bangkok rental yields right now.