Source: Economist.com
If the local cost of a Big Mac converted into dollars is above $5.28, the price in America , a currency is dear; if it is below the benchmark, it is cheap. The average cost of a Big Mac in the euro area is €3.95, or $4.84 at the current exchange rate. That implies the euro is undervalued by 8.4% against the dollar.
According to the Economist’s Big mac chart, the AUD is undervalued vs the USD by between 10-25%.
Source: Economist.com