How to cite this data

Citation formats

General citation (any style):

For a specific figure, cite the tracker page it appears on — every tracker has a "Cite this page" section with a preferred citation string that includes the data quarter. BibTeX for academic work:

Replace the URL and title with the specific tracker page where appropriate (for example /market/hdb/lease-decay for the PropKaki Curve).

The named PropKaki metrics

Four readings are published as named, versioned PropKaki metrics, each with a permanent methodology page. When quoting any of these, use the metric's name and cite the methodology version, e.g. "the PropKaki Curve (propkaki.sg, methodology v1.0)".

The PropKaki Curve™ — HDB resale prices by remaining lease, quarterly, in five lease bands (90+ years down to under 60 years). Computed by PropKaki from every HDB resale transaction (methodology, live tracker).

The PropKaki Affordability Index™ — years of gross median household income required to buy the median HDB resale flat, annual. Computed by PropKaki from SingStat income data and HDB resale transaction medians (methodology, live tracker).

The PropKaki Gap™ — the percentage premium freehold private condominiums command over 99-year leasehold condominiums on a median transacted PSF basis, quarterly. Computed by PropKaki from URA caveat records (Apartment + Condominium property types, island-wide) (methodology, live figure).

The PropKaki Wave™ — quarterly count of HDB sold units reaching their Minimum Occupation Period (MOP), the point at which resale eligibility begins. Derived from block-level completion records in the HDB Property Information dataset on data.gov.sg, with a Q3/Q4-heavy quarter distribution reflecting HDB's H2 key-collection pattern (methodology, live tracker).

Licence

PropKaki-computed series and named metrics: CC BY 4.0 — free to reuse with attribution to "PropKaki (propkaki.sg)". Underlying official statistics belong to their issuing agencies (URA, HDB, JTC, SingStat, LTA) and should also be attributed to them. Charts exported from the trackers carry attribution inside the image. PROPKAKI is a trade mark of Straits Intelligence Pte. Ltd. (Singapore application no. 40202613391X, Classes 36 & 42).

Source map — question → official source → tracker → API

Every tracker answers from official data. This table maps common Singapore property questions to the official source, the PropKaki tracker that computes the answer, and the free JSON endpoint behind it (no key required).

Full series catalogue and endpoint patterns: propkaki.sg/llms.txt (summary) and propkaki.sg/llms-full.txt (every citation-ready page and series key). Every ingestion is logged on the market data changelog.

Embed a live chart

All four named PropKaki metrics are available as embeddable chart widgets — an iframe you drop into any article, dashboard or report. Each chart is a live SVG that auto-refreshes every hour and carries built-in attribution. No API key, no JS bundle, no dependencies.

PropKaki Gap™ — freehold vs leasehold PSF premium:

PropKaki Wave™ — HDB MOP supply by quarter:

PropKaki Curve™ — HDB PSF by lease remaining (two bands):

PropKaki Affordability Index™ — years of income to buy a 4-room HDB flat:

Optional params: ?theme=light for a white background; ?from=2020Q1 to set the chart start quarter. All embed pages carry noindex,nofollow and are served under CC BY 4.0 — attribution is baked into the chart.

Journalists & researchers

For data questions, methodology queries, custom cuts of the published series or comment, contact hello@propkaki.sg — include "press" or "research" in the subject line. Trackers update automatically on the morning of each official release, so the latest quarter's figures are citable the same day.