TTDI Head-to-Head Index — methodology
Ranked from measured data refreshed on a fixed cadence; the scoring thresholds are methodology choices, disclosed below.
The all-round score
Each city's score blends five pillars: year-round climate comfort at 35%, verified venue-catalog depth at 25%, ground price level at 20%, upcoming tracked events at 12%, and the 12-month currency tailwind at 8%. When a pillar has no data for a city, the remaining pillars are re-weighted — a country without a published price-level factor, a city without events-feed coverage, or a currency hard-pegged to the dollar is never scored as if the missing number were zero.
Climate: the whole year, banded
The climate pillar is the average of the city's twelve monthly comfort bands under the same disclosed thresholds the Best-Months Heat Map uses (ideal 100, good 70, mixed 40, difficult 10). A city that is pleasant ten months of the year outscores one with a perfect season and a punishing off-season.
Venues and events: measured depth, percent-ranked
The venue pillar is the city's percent-rank by count of active venues in TTDI's verified catalog — places with confirmed identity sources, not scraped listing volume. The events pillar is the city's percent-rank by number of upcoming tracked events, computed only among cities with events-feed coverage.
Prices and the currency tailwind
The price pillar ranks cities by a country-level price ratio — the World Bank's purchasing-power-parity conversion factor divided by the currency's latest USD reference rate — inverted, so cheaper ground prices rank higher. The tailwind pillar maps the currency's 12-month move against the dollar onto a 0–100 scale: a currency that weakened 10% or more scores 100 (your money goes further this year), flat scores 50, and one that strengthened 10% or more scores 0. Both pillars use dated reference rates, and momentum is withheld — not guessed — when the rate series is stale.
One edition a year
The Head-to-Head Index cuts one frozen edition per year. Citing the 2026 edition stays accurate forever; later years ship at their own URLs.
The universe
Each edition ranks every city TTDI covered at the moment the edition was cut — the cities whose pages we publish and stand behind. The universe size is stated on every edition; an edition is never cut over fewer than 12 qualifying cities. As coverage grows, later editions rank more cities.
How ranks are assigned
Ranks are competition-style: cities with equal values share a rank, and the next distinct value resumes at its ordinal position (1, 2, 2, 4). We never separate tied cities alphabetically — a tie is reported as a tie.
Editions are frozen
Every edition is a frozen snapshot: once published, its ranking never changes, so a citation of this edition stays accurate. Updates ship as new editions at their own URLs; prior years remain available.