Economic Convergence Calculator

Mountain to Climb shows how long a poorer economy would take to catch up with a richer one. Pick two countries, choose an indicator such as GDP per capita (PPP), set a growth rate for each, and the calculator plots the path and the year the gap closes. It covers 217 countries and several indicators, using World Bank, OECD and UN data.

What is economic convergence?

Economic convergence is the idea that poorer economies tend to grow faster than richer ones and so narrow the gap in income per person. Catch-up growth is the faster growth a follower achieves by adopting technology and practices the leaders already use, and by investing in capital that is scarce at low incomes. Whether a particular country actually converges depends on its institutions, investment, education and policy.

How is the catch-up time calculated?

If the chaser grows at rate g and the target at rate h, the gap closes when (1 + g)^t × chaser = (1 + h)^t × target. Solving for t gives t = ln(target / chaser) / ln((1 + g) / (1 + h)). The result depends only on the starting ratio and the growth differential. If the chaser does not grow faster than the target, it never catches up.

For example, Poland reached about 87% of UK GDP per capita (PPP) in the latest data. At 4% growth against 1%, that gap closes in a few years. Results are scenarios that follow from the growth rates you choose, not forecasts.

GDP per capita: PPP or nominal?

PPP (purchasing power parity) adjusts for local price levels and is better for comparing living standards. Nominal US-dollar GDP per capita uses market exchange rates and moves with currencies. Some countries, such as Ireland and Luxembourg, have GDP figures inflated by multinationals or cross-border commuting; the calculator flags these.

For developers and AI agents

The same calculation is available as a JSON API and as embeddable SVG charts. See llms.txt, the OpenAPI description and example pages such as Poland and the United Kingdom.