Are you paying too much for an old HDB flat?

How to figure out if an old HDB flat is worth its asking price? Besides looking at the psf, look at also the psf on a per annum of the balance lease. Here is an example:

a Bukit Timah flat of 1,345 sq ft that sold for $950,000, reported in The Straits Times recently. That is $706 psf.
That flat was built in 1974 on a 99-year lease. It thus has 56
years of lease remaining. The price psf on a per annum of
balance lease basis is $12.60.
Is that a good price?

Check out the full report The Straits Times