Every market on Rent Index resolves to one number: a city's rent index.

Every covered city pulls live asking-rent listings — price per square metre or square foot — from multiple major rental platforms, never just one, so no single site’s pricing quirks move the index alone.

Duplicate listings, obvious data errors, and outliers (top and bottom slice per neighbourhood) are filtered out before anything is averaged.

What is left is grouped by bedroom count and neighbourhood, converted to a common price-per-m² basis, so a studio in one district cannot quietly drag down the index for three-bedrooms across town.

Where a public official rent statistic already exists for a city — a national statistics office, a housing authority, a land registry — the index is checked against it as an external sanity check. A guardrail, not the primary feed.

The kind of public source used for calibration where available — e.g. INSEE in France, the ONS in the UK, HUD data in the US, land-registry data in Dubai and Singapore. Rent Index is not affiliated with these bodies; they are cited as the category of benchmark used, not as partners.

The resulting number, and the full history of how it moved, is published before any market opens on it. Nothing is recalculated after the fact to fit a trade.