The Iranian Rial — Oil and Sanctions Shrank It Until Parliament Voted to Drop Four Zeros
Summary
The Iranian rial did not collapse in a single catastrophic spike; it eroded, year after year, until it was worth so little that the parliament legislated to strike four zeros off it and rename the unit the toman. The verdict here is devaluation: an oil-dependent economy, squeezed by international sanctions and chronic high inflation, watched its currency fall from roughly 70 rials to the US dollar in 1979 to around 162,500 on the free market by May 2020 — and on 4 May 2020 the Islamic Consultative Assembly approved a plan to redenominate, making one new toman equal to 10,000 old rials. That redenomination is best understood as a symptom dressed as a reform: a legislative acknowledgment that the rial unit had become too small to be usable, not a measure that halted the decline. The crisis is ongoing.
The mechanism is the classic oil-state version of the resource curse, compounded by geopolitics. Iran's public finances and foreign-exchange earnings rest heavily on crude exports, which makes the state's revenue hostage both to the oil price and to whether Iran is permitted to sell at all. When the United States withdrew from the nuclear deal in 2018 and reimposed "maximum pressure" sanctions, that second variable turned against Iran sharply: oil-export revenue fell from around 51 billion dollars in 2018 to roughly 5 billion in 2020. A government facing a revenue collapse and cut off from world finance leaned on monetary financing, and inflation, already chronic, settled into a punishing range — roughly 30 percent in 2020 and in the 40s through the years that followed.
The redenomination itself must be described precisely, because its status is easily overstated. The May 2020 parliamentary vote approved removing four zeros and renaming the rial the toman, with a smaller sub-unit, the parseh (one toman = 100 parsehs). But the measure was legislated and phased, not instantly executed: it required the approval of the Guardian Council, and the central bank was to be given up to two years to withdraw the old rial, with rial and toman circulating in parallel during the transition. The "toman" was in any case already the unit Iranians used in everyday speech, informally dividing rial prices by ten. The reform proposed to make official what the street had long done.
What it did not do was anchor the currency. After the 2020 vote the rial kept falling, reaching record lows against the dollar in the years that followed as sanctions persisted and inflation stayed high. A redenomination that strips zeros without changing the fiscal and external pressures behind the inflation does not stabilize a currency; it relabels it. This file records the dated devaluation and the legislated reform; it does not claim the rial was saved.
Timeline
An Economy Wired to the Oil Price
Iran's monetary fate is bound to a single commodity. Crude oil and its associated revenues have long anchored the state budget and the country's supply of foreign exchange, which means the government's finances rise and fall with two things it only partly controls: the world oil price, and Iran's ability to find buyers. This is the resource curse in its petrostate form — not a sudden windfall squandered, but a structural dependence that leaves the entire economy, and its currency, exposed to swings in a market set far from Tehran.
The first variable, price, has buffeted Iran for decades; the oil-price collapses and recoveries since the 1980s map onto the rial's bouts of weakness. The second variable, access, is where geopolitics becomes monetary policy. Sanctions do not merely slow Iran's economy; they attack the very mechanism by which an oil state earns the hard currency that backs its money. When buyers retreat and revenues fall, the central bank's foreign reserves thin, the official exchange rate becomes harder to defend, and the gap between the official rate and the black-market rate yawns open — a spread that itself signals the market's verdict on the currency.
A government in that position has limited room. Cut off from much of the world financial system, unable to borrow abroad freely, and facing a shrinking revenue base, Iran covered fiscal gaps in part through monetary expansion. The result was chronic inflation — not the hour-by-hour hyperinflation of Zimbabwe or Yugoslavia, but a persistent, grinding rate that ran in the tens of percent year after year, compounding into an enormous loss of value over a generation. From 70 rials to the dollar in 1979 to six figures by 2020 is the arithmetic of decades of that grind.
The Sanctions Shock and the Grinding Inflation
The decisive turn came in 2018. The United States withdrew from the 2015 nuclear accord and reimposed sweeping sanctions under a "maximum pressure" policy aimed squarely at Iran's oil exports — the country's economic lifeline. The effect on revenue was severe and quick: oil-export earnings fell from around 51 billion dollars in 2018 to roughly 5 billion by 2020, a collapse of the state's principal source of foreign exchange in barely two years. The economy contracted, and the rial, which had traded around 34,000 to the dollar in the post-deal calm, slid to roughly 190,000 by September 2018 and on toward 162,500 by the time of the 2020 redenomination vote, with the black market leading the official rate down.
Inflation tracked the currency's fall. After the sanctions shock, Iran's annual consumer-price inflation ran at roughly 30 percent in 2020 and settled into the low-to-mid 40s percent in the years that followed — high, persistent, and corrosive without ever crossing the technical hyperinflation threshold. For Iranian households the consequence was the familiar tax of inflation: imported goods priced in a dollar that kept getting more expensive, savings in rial steadily eroded, and a constant pressure to convert cash into foreign currency, gold, or goods before it lost more value. Real people are living through this; the loss of purchasing power has been a daily fact of Iranian life across the period this file covers.
By 2020 the rial had become almost comically unwieldy as a unit — not because any single note was absurdly large, but because everyday sums required so many of them. The largest standard banknote was 100,000 rials, and the central bank supplemented it with "Iran Cheques," bearer instruments that circulated like cash in much larger denominations, up to the millions of rials, precisely because the base unit was too small for ordinary transactions. Iranians had long since stopped speaking in rials at all, quoting prices in tomans — informally lopping a zero in their heads. The currency's own users had redenominated it years before the parliament got around to it.
Legislating the Toman — A Reform Described Precisely
On 4 May 2020 the Islamic Consultative Assembly approved a plan to formalize what the street already practiced: strip four zeros from the rial and rename the currency the toman, with one toman equal to 10,000 old rials, divided into 100 parsehs. A government spokesman framed it as a measure to simplify transactions. It was, on its face, an admission of how worthless the rial unit had become — you do not legislate to delete four zeros from a currency that is doing well.
The precise status of the reform matters and is easy to get wrong. The May 2020 vote was an approval in parliament, not an instant changeover. The plan required ratification by the Guardian Council, the body that vets legislation, before it could take effect; the central bank was then to be given up to two years to phase the old rial out, with the rial and the toman circulating side by side through the transition. This was a legislated, phased redenomination — a multi-year administrative process, not a single overnight reset of the kind that retired the German mark or the Yugoslav dinar. (A further parliamentary vote in 2025 revisited the redenomination with broadly similar terms, underscoring that the change had not been cleanly executed in the years after 2020.)
This is why the verdict on the record is devaluation rather than redenomination as a completed act. The dated, documented monetary event of this period is the rial's collapse to a tiny fraction of its former value — the fall from 70 to six figures against the dollar, driven by oil dependence and sanctions. The toman plan is the reform that fall provoked, and it is properly described as legislated and phased, not as a stabilization. Stripping zeros, whenever it is finished, will change how Iranians write prices; it will not, on its own, change what those prices do, and Iran's inflation and currency weakness have continued regardless.
The Five Factors
Aftermath
The redenomination did not stop the rial's decline, because a redenomination cannot. In the years after the 2020 vote the currency reached successive record lows against the dollar, passing several hundred thousand to the dollar on the open market as sanctions persisted, the oil-export channel stayed constrained, and inflation held in the 40s percent. The toman plan moved slowly through Iran's legislative machinery — phased, contingent, and revisited again by a later parliament — rather than landing as the clean break a stabilization requires. The crisis this file describes is, plainly, not over.
The cost has fallen on ordinary Iranians, who have absorbed years of high inflation and a currency that loses value faster than wages rise. Savers see rial balances shrink in real terms; importers and the households who buy what they import pay more each year; the flight into dollars, gold, and durable goods is the rational response of people trying to outrun the erosion of their money. The lasting significance of the episode is diagnostic: the toman redenomination stands as a formal confession of how far the rial had fallen — a state legislating away four zeros it could no longer pretend were meaningful. Whether the toman, once fully implemented, becomes anything more than the rial with a shorter number depends entirely on resolving the oil dependence and the sanctions pressure that hollowed the rial out, and neither was resolved by the vote.
Lessons
- Diversify away from a single export commodity before its price or your access to its market turns against you — a currency anchored to one externally priced good inherits all of that good's volatility.
- Treat sanctions as a monetary event, not only a trade one: cutting off oil revenue attacks the hard-currency base that backs the money, and the black-market spread will price the damage in real time.
- Watch for the grinding inflation as well as the dramatic spike — decades in the tens of percent can hollow a currency as completely as a burst of hyperinflation, while being easier to ignore.
- Read the warning signs from the public: when citizens supplement the base note with larger bearer instruments and quote prices in a shorthand unit, the currency has already failed at its job.
- Describe a redenomination honestly — a legislated, phased plan to drop zeros is an admission of lost value, not a stabilization, and the inflation behind it will continue until its causes are addressed.
References
- Iran Revamps and Renames Currency The Iran Primer, U.S. Institute of Peace
- Iranian rial Wikipedia
- Iran to introduce currency re-denomination in tomans Coin World
- How US sanctions and external threats destroyed Iran's economy Middle East Eye
- Iranian economic crisis Wikipedia