Income levels — two options:
Current USD: GDP per capita in current US dollars (
NY.GDP.PCAP.CD).
PPP: GDP per capita in current international dollars, adjusted for purchasing power parity (
NY.GDP.PCAP.PP.CD). PPP removes price-level differences between countries.
Growth rates — two options:
Real series: World Bank official real GDP per capita growth, stripping out inflation. Current USD mode:
NY.GDP.PCAP.KD.ZG. PPP mode:
NY.GDP.PCAP.PP.KD.ZG.
Implied from data: arithmetic mean of year-over-year % changes across the most recent 5 available years of the chosen GDP series. This is a nominal rate.
Base year: both countries aligned to the older of their two latest data years.
Catch-up formula: t = ln(GDP_B / GDP_A) / ln((1 + g_A) / (1 + g_B)).
Sources
World Bank, World Development Indicators — GDP per capita: NY.GDP.PCAP.CD (current US$) and NY.GDP.PCAP.PP.CD (PPP, current international $); real per-capita growth: NY.GDP.PCAP.KD.ZG and NY.GDP.PCAP.PP.KD.ZG.
data.worldbank.org.
All figures are stored locally (gdp-current-usd.json, gdp-ppp-latest.json, gdp-real-growth-latest.json) — no live API calls at runtime.