Hyperinflation is an exceptionally rapid increase in the general price level that severely erodes money’s purchasing power and usefulness. Research often uses Cagan’s monthly threshold. Accounting also considers other indicators, so monthly, annual and multi-year figures cannot simply be treated as interchangeable.
Economist Phillip Cagan gave researchers a widely used boundary: an episode starts in the month when price growth exceeds 50 % per month. A study from the International Monetary Fund (IMF) also recalls his end rule: the final month is the one before inflation drops below that threshold and stays there for at least a year. A single quieter month is not enough, and the end can only be confirmed retrospectively. This is a convention for comparing events, not a universal legal definition. When someone calls an economy hyperinflationary, check whether they use Cagan’s definition or another. Otherwise, apparently conflicting claims may simply use different measures. [1]
Take two months of growth at 50 % each. Our example purchase initially costs 100, then 150 and then 225. The total increase is 125 %, not 100 %, because the second rise starts from a higher price. If the same 50 % repeated for all 12 months, annual growth would be about 12 874.63 %, not 600 %. We multiply successive price ratios rather than add the percentages. This is not a country’s historical record or a claim that exactly 50 % exceeds Cagan’s threshold. The example shows why a number without its time period can be so misleading. [1]
We immediately notice a sharp petrol price increase. But one price tag does not tell us how the general price level has changed. The IMF explains it through an index tracking a defined basket of goods and services over a specified period. A jump in a share price or bitcoin (BTC) is likewise not a measure of domestic inflation. We need a comparable monthly series, a known methodology and acknowledgement of missing or delayed data. Even a banknote covered in zeros cannot replace the missing index. Debasement, a broader term for deterioration in money’s value, can also concern a coin’s metal content; it is not automatically synonymous with hyperinflation. [2]
Germany’s central bank, the Bundesbank, describes Germany in 1923, when wages in some places were paid daily. People rushed to exchange notes for goods, merchants rewrote prices and some trade shifted to exchanges for food or coal. Money was failing as a Medium of Exchange, a means of trading, and as a Store of Value, a way to carry value into the future. Purchasing Power means how much it buys: waiting could sharply reduce that amount. The effects were not identical for everyone. They depended on how quickly wages adjusted, the currency of debt and when someone received a payment and could spend it. [3]
When a state persistently spends more than it collects, it must finance the gap. A study of modern episodes published by the IMF links their onset to large deficits, financing that includes Seigniorage, the return from issuing money, and difficulties sustaining an exchange-rate regime, meaning the chosen rules governing the exchange rate. This is not one universal script. If people also become unwilling to hold domestic money, faster spending or conversion can reinforce the loss of confidence. Yet growth in Monetary Base, cash and the balances banks hold in accounts at the central bank, alone does not prove that hyperinflation is under way. Nor does a one-off supply disruption. Causes require evidence, not inference from a single chart. [4]
Accounting standard IAS 29 concerns an entity whose functional currency, the currency of its primary economic environment, belongs to a hyperinflationary economy. Its indicators include cumulative inflation over 3 years of around 100 % or more, and prices, interest or wages linked to an index. That is not Cagan’s 50 % per month. An IFRIC decision, from the standards interpretation committee and published in July 2025, describes assessing several indicators using judgement rather than reaching a conclusion from just one. The aim is to avoid comparing monetary units with vastly different values in financial statements. Restating them using an index does not restore the purchasing power a business or saver has already lost on cash balances. [5] [6]
The Bundesbank dates the introduction of the Rentenmark to November 1923. A genuine monetary-regime change must not be confused with merely renaming units. In our separate example, 1 000 old units become 1 new unit. Balances and prices are converted in the same ratio, so the renaming alone supplies no more goods. This is a model, not the historical conversion rate. Disinflation also means slower price growth, not an automatic return to earlier prices. When price tags stop changing so quickly, that is an important improvement; it does not erase past losses in savings. [3]
Bitcoin.org describes limited BTC issuance, but also a price determined by supply and demand. People escaping a local currency may seek other currencies, goods or various assets; they need not choose Bitcoin. And if BTC’s price shoots up in a collapsing currency, part of the movement may reflect that currency’s fall. The exchange rate alone does not prove an equal real gain measured in a shopping basket. Access to exchange, secure custody and BTC price fluctuations still matter. Limited issuance explains a property of the system, not a guaranteed outcome for every person in a currency crisis. [7]
For the clearest picture, read this entry together with Seigniorage, Debasement, Disinflation, Purchasing Power. The reverse links also lead from Seigniorage, Debasement, Disinflation.