In 1956, Phillip Cagan wrote "The Monetary Dynamics of Hyperinflation"^[1], generally regarded as the first serious study of hyperinflation and its effects. In it he defined hyperinflation as a monthly inflation rate of at least 50% (prices doubling every 51 days).

International Accounting Standard 29 describes four signs that an economy may be in hyperinflation:

The general population prefers to keep its wealth in non-monetary assets or in a relatively stable foreign currency. Amounts of local currency held are immediately invested to maintain purchasing power.

The general population regards monetary amounts not in terms of the local currency but in terms of a relatively stable foreign currency. Prices may be quoted in that currency.

Sales and purchases on credit take place at prices that compensate for the expected loss of purchasing power during the credit period, even if the period is short.

Interest rates, wages and prices are linked to a price index and the cumulative inflation rate over three years approaches, or exceeds, 100%.