Block 521 Serangoon Nth Ave 4

Neutral read: bigger bars = more nearby flats able to list in that year; smaller bars = less new competition. A haio estimate — not advice on when to sell.

Two precision tiers: flats resold in the last 5 years count from the resale month (MOP actually runs from key collection); never-resold BTO flats are a year-level estimate from the block's completion year + 5 (+10 for Plus/Prime/PLH blocks).

MOP estimated as HDB completion year + 5 (standard scheme); +10 for Plus/Prime/PLH blocks. Able-to-sell figure nets out resale transactions in the last 5 years (those buyers' own MOP restarted). haio estimate — not guaranteed to reflect individual flat eligibility.