BTO
Build-To-Order

Just Tell Me
BTO means Build-To-Order: an HDB sales exercise where eligible buyers apply for new public housing flats in selected projects.
Also called: Build-To-Order, build to order
Explain Like I’m Five
Think of a BTO launch as HDB offering a new set of housing projects to choose from. Eligible buyers apply for the offered location and flat type, and a computer ballot decides who gets a place in the queue to choose a flat. Applying is a chance to buy a flat, not a promise that you will get one.
Where You’ll Run Into It
You might hear friends discussing a BTO launch when they are thinking about a home. Each sales exercise offers different flat types across a selection of towns, giving buyers a choice of projects to apply for.
In conversation, “our BTO” can mean the flat someone is buying through this process, rather than the sales exercise itself.
Example
“We’re looking at the next BTO launch.”
They mean they are considering the new flats HDB will offer in that exercise. They have not necessarily applied for, or secured, a flat yet.
The Part People Get Wrong
BTO is one way HDB sells new flats, not the name for every HDB flat. There are also Sale of Balance Flats exercises and open booking of flats. Eligibility and application conditions apply; check HDB’s official information for your situation.