What Is Deflation?
Definition
Deflation: A fall in the general level of prices of goods and services, when the yearly change of the price index turns negative. With deflation, the same money buys more over time.
Deflation is a fall in the general level of prices of goods and services: a negative inflation rate. In Türkiye it would show in TÜİK’s consumer price index (CPI, TÜFE): deflation means the index’s annual change is below zero. Deflation raises purchasing power. Slower inflation is not deflation; prices still rise. That is called disinflation.
Where it appears in the formulas
A price change is (new price / old price − 1) × 100, and with deflation it is negative. For example, an index that falls from 100 to 98 changes by −2% (percentage change calculator). The inflation calculator accepts only rates of 0 or more, so it does not model deflation.
Türkiye’s recent record
In TÜİK’s data from January 2020 to August 2026, the annual CPI change was never negative. The lowest annual rate in that period was 10.94%, in April 2020.