Revaluation is a change in a price of a good or product, or especially of a currency, in which case it is specifically an official rise of the value of the currency in relation to a foreign currency in a fixed exchange rate system. In contrast, a devaluation is an official reduction in the value of the currency. Under floating exchange rates, a rise in a currency's value is an appreciation. Altering the face value of a currency without changing its purchasing power is a redenomination, not a revaluation (this is typically accomplished by issuing a new currency with a different, usually lower, face value and a different, usually higher, exchange rate while leaving the old currency unchanged; then the new replaces the old).

In a fixed exchange rate system, the central bank maintains an officially announced exchange rate by standing ready to buy or sell foreign currency at that rate. In general terms, revaluation of a currency is a calculated adjustment to a country's official exchange rate relative to a chosen baseline. The baseline could in principle be anything from wage rates to the price of gold to a foreign currency. In a fixed exchange rate regime, only a decision by a country's government (specifically, its central bank) can alter the official value of the currency.

For example, suppose a government has set 10 units of its currency equal to one US dollar. To revalue, the government might change the rate to 9.9 units per dollar. This would result in that currency being slightly more expensive to people buying that currency with U.S. dollars than previously and the US dollar costing slightly less to those buying it with foreign currency.