The instability of the exchange rate and the individual banking system and the impossibility of using the Visa card or Master card makes it difficult for passengers to travel, raising the question of which currency to bring to Iran. The best currency you can bring to Iran is the US dollar (USD) or Euro(EUR). Other currencies, such as the Pound (GBP) and the Australian dollar (AUD), are exchangeable in currency exchange, but due to the unpopularity of these currencies, the commission for foreign exchange may be slightly higher.
The best and fastest way to exchange money is by going to the currency exchange. If you go to a bank, it will take more time. You can easily find a currency exchange in all the province centers and, as far as possible, these are preferable to dealing with street currency exchanges.
On a trip to Iran, the currency issue is always confusing for travelers. There are two types of currency in Iran. Tuman and Rial. Rial is the official unit of the country and is usually used in official bank transactions and banknotes. But Tuman is an unofficial unit that people use in their daily deals. So if you take a taxi, surely the taxi driver will quote you the price in Tuman. In short, each one Tuman equals 10 Rials. The value of banknotes are published in English and Persian in units of Rials. But the value of the coins is engraved only in Persian.
Due to bank boycotts against Iran, the banking system of Iran is completely independent and therefore there is no possibility to use Master card and Visa card. So you have to bring adequate cash to last the whole trip. But for more convenience, you can get an Iranian Prepaid card from one of the bank branches of Iran, and use it in stores and restaurants during your stay in Iran.