What is purchasing power parity (PPP)?
Understand the common purchasing-power unit behind cross-country comparisons.
By RankMyIncome · Updated 22 October 2026
A common basis
National price levels differ. PPP expresses amounts on a common purchasing-power basis rather than comparing raw local-currency numbers. RankMyIncome uses the conversion factor stored with each country in its WID snapshot. The global comparison uses the WO-PPP world distribution and the dataset’s USD PPP unit. It does not fetch live foreign-exchange quotes.
The exact arithmetic
Let A be local annual income and f be local currency per world unit. The common-unit amount is A ÷ f. For an equivalent in country B, multiply that amount by B’s factor. Thus B-equivalent income = A-income ÷ A-factor × B-factor. Converting back with the same factors recovers the original value apart from ordinary floating-point rounding.
Purchasing power and rank differ
Equal purchasing power does not imply equal national rank. Each country has its own distribution. A common-unit amount can lie near one country’s middle and another’s top. The comparison tool reports national positions separately and uses the same world curve for global context.
Limits of the comparison
PPP does not quote city rents, a particular apartment, school fees, taxes or a personal spending basket. Historical national factors cannot provide a complete relocation budget or a current-price forecast. Try the purchasing-power comparison and inspect both source years. The median ranking keeps common-unit values separate from local currency.
Sources and calculation notes
Numerical examples use the public dataset shared by all tools. Definitions: WID methodology and codes dictionary. Calculations: RankMyIncome source code. Hypothetical scenarios illustrate arithmetic, not observed market salaries.