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Strait of Hormuz Explained: What If It Closes

How much oil and LNG pass through the Strait of Hormuz, which pipelines bypass it, the law of transit passage, and what a closure does to prices and insurance.

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The Strait of Hormuz is the only sea exit from the Persian Gulf. In 2025 about 20 million barrels per day of crude oil and oil products passed through it, around a quarter of world seaborne oil trade, plus almost a fifth of global LNG trade (IEA). If it closes, that cargo cannot be rerouted by sea. Two pipelines can carry part of it out, so a closure strands supply, raises prices and insurance costs, and leads importing governments to release emergency stocks. All of that has been happening since March 2026, when traffic through the strait fell to a small fraction of normal.

Where the strait is and how ships use it

The strait lies between Oman and Iran and links the Persian Gulf with the Gulf of Oman and the Arabian Sea. The IEA’s factsheet (last updated February 2026) puts its narrowest point at 21 nautical miles (39 km). Shipping uses a traffic separation scheme: one 2-mile-wide channel (3.7 km) inbound, one outbound, and a 2-mile buffer between them. EIA notes that it is deep and wide enough for the world’s largest crude tankers (EIA).

How much oil goes through Hormuz

Two agencies publish estimates from different tanker-tracking data, so their figures differ slightly.

  • EIA (last updated 3 March 2026): total oil flows averaged 20.9 million b/d in the first half of 2025 and 20.7 million b/d in 2024. That was about 20% of global petroleum liquids consumption and a quarter of maritime oil trade (EIA).
  • IEA (February 2026): in 2025, nearly 15 million b/d of crude, close to 34% of global crude trade, plus around 5 million b/d of products (IEA).

The IEA’s 2025 breakdown by exporter, in million barrels per day (analysis based on Kpler):

ExporterCrude and condensateProductsTotal
Saudi Arabia5.430.806.23
Iraq3.320.313.63
United Arab Emirates2.021.223.24
Iran1.690.722.41
Kuwait1.400.972.37
Qatar0.730.691.43
Saudi-Kuwaiti Neutral Zone0.350.000.35
Bahrain0.000.210.21
Total14.954.9319.87

Where the cargo goes

EIA estimates that 89% of the crude and condensate through the strait in the first half of 2025 went to Asia, and that China, India, Japan and South Korea together took 74%. The US imported about 0.4 million b/d through it in that period, about 7% of its crude imports. The IEA puts flows to Europe at around 600,000 b/d, about 4% of the region’s crude, in 2025.

LNG

About 93% of Qatar’s LNG exports and 96% of the UAE’s transit the strait. Just over 112 bcm passed through in 2025, almost 20% of global LNG trade, and almost 90% of it went to Asia. Bangladesh, India and Pakistan imported almost two-thirds of their LNG this way in 2025 (IEA). LNG has no pipeline bypass.

Can oil bypass the Strait of Hormuz?

Only partly. All figures below are from the IEA factsheet unless noted.

  • Saudi East-West pipeline (Abqaiq to Yanbu on the Red Sea): design capacity 5 million b/d. Aramco reported raising it to 7 million b/d in March 2025, but sustained flows at that level have not been tested. About 2 million b/d was in use in early 2026, leaving 3 to 5 million b/d spare.
  • UAE Habshan-Fujairah pipeline (ADCOP, 400 km to the Gulf of Oman): nameplate 1.5 million b/d, reported capacity close to 1.8 million b/d. The UAE already ships about 1.1 million b/d through it, leaving room for up to 700,000 b/d more.
  • Iran’s Goreh-Jask pipeline is effectively non-operational, according to the IEA.

Estimates of usable spare bypass capacity differ by source and date: about 2.6 million b/d (EIA, June 2025), about 4.7 million b/d of Saudi and UAE bypass capacity (EIA, March 2026), and 3.5 to 5.5 million b/d (IEA, February 2026). By our comparison of the IEA figures, even 5.5 million b/d is under a third of the roughly 20 million b/d that normally transits. Iraq, Kuwait, Qatar, Bahrain and Iran have no comparable route.

Who controls the strait: the law of transit passage

Part III of the UN Convention on the Law of the Sea (UNCLOS) governs straits used for international navigation. Article 38 gives all ships “the right of transit passage, which shall not be impeded.” Article 44 says bordering states “shall not hamper transit passage” and “there shall be no suspension of transit passage.” Under Article 41, sea lanes and traffic separation schemes must be adopted by the competent international organization.

The UN Treaty Collection, read on 28 October 2026, shows:

  • Oman signed on 1 July 1983 and ratified on 17 August 1989.
  • Iran signed on 10 December 1982, with no ratification recorded. Its signature declaration says “only states parties to the Law of the Sea Convention shall be entitled to benefit from the contractual rights created therein”, naming transit passage under Article 38.
  • The United States is not listed as a signatory or party.

So Iran’s stated position is that non-parties cannot claim treaty transit passage, and the US is a non-party. How far the regime binds non-parties is disputed, and that dispute shapes what each side calls lawful in a crisis.

What happens if the Strait of Hormuz closes

The effects below are the ones described in official analysis. Most of them have played out since March 2026.

Supply is stranded

A Suez or Red Sea disruption can be avoided by sailing around Africa. Gulf-loaded cargo has no such option: EIA notes that most Hormuz volumes “have no alternative means of exiting the region” beyond the pipelines (EIA). Once storage in exporting countries fills, producers shut in output (EIA, April 2026). The IEA adds that a prolonged disruption would also lock up most of the world’s spare production capacity, held mainly by Saudi Arabia and above 4 million b/d in the fourth quarter of 2025, excluding sanctioned countries.

Prices

Prices react even to the threat. Between 12 and 13 June 2025, with no blockage, Brent rose from $69 to $74 per barrel (EIA). Although most Hormuz crude goes to Asia, the IEA says the price effect would be global. For gas, it estimates that losing Hormuz LNG would remove over 300 million cubic metres per day that other exporters, already near capacity, could not quickly replace.

Insurance and listed areas

London hull war cover follows the Joint War Committee (JWC) of the Lloyd’s Market Association and the IUA. It publishes “Listed Areas” where vessels face increased risk of war perils. Ships entering them must notify underwriters. Premiums are negotiated between underwriters and brokers, and the JWC says it plays no role in rating. After the JWC widened its Gulf listings in March 2026, the Joint Maritime Information Center (JMIC), which publishes advisories through UKMTO, observed that “insurance terms may act as a practical gating factor for transit decisions independent of any legal navigational closure” (JMIC, 8 March 2026). In practice, ships can stop sailing without any formal closure.

Emergency stocks

Each IEA member with a stockholding obligation must hold oil equal to at least 90 days of net imports. In a severe disruption members can agree a collective action, with each country’s share proportional to its oil consumption (IEA). By October 2026 there had been six: 1991, 2005, 2011, two in 2022, and the largest on 11 March 2026.

Past disruptions

The Tanker War, 1984 to 1988

During the Iran-Iraq war, Iraq struck Iran’s Kharg Island terminal in March 1984 and both sides then attacked shipping. By the end of 1987 Iraq had made 283 attacks on shipping and Iran 168, killing 116 merchant sailors, with 37 missing and 167 wounded, according to the US Naval History and Heritage Command. The same account says the attacks did not cut off Gulf oil and “all they really did was drive up insurance rates.” The US reflagged 11 Kuwaiti tankers, and US Navy escorts under Operation Earnest Will ran from 24 July 1987 to 26 September 1988.

The 2026 disruption

A dated record from official sources:

  • 28 February 2026: a Middle East conflict began that, in the IEA’s words, “impeded oil flows through the Strait of Hormuz” (IEA, 11 March 2026).
  • 3 March: the JWC added Bahrain, Djibouti, Kuwait, Oman and Qatar to its Listed Areas (JWLA-033).
  • 8 March: the JMIC rated regional risk CRITICAL and reported one confirmed commercial transit in 24 hours, against a historical average of about 138 vessels a day (JMIC Update 008).
  • 11 March: the IEA said Hormuz crude and product exports were below 10% of pre-conflict levels. Its 32 members agreed to make 400 million barrels of emergency stocks available (IEA).
  • March and April: EIA estimated that six Gulf producers shut in 7.5 million b/d of crude in March, when Brent averaged $103 per barrel (EIA, 7 April 2026). The IEA put April Gulf output 14.4 million b/d below pre-war levels (IEA, May 2026).
  • 18 June: the JMIC lowered the strait’s threat level to MODERATE after the US and Iran announced intentions to open it, but advised avoiding the traffic separation scheme because of mines and using a southern route along Omani territorial waters (JMIC 009-26).
  • 12 July: Iran proclaimed the strait closed. The JMIC said the southern route remained available and rated the threat SEVERE (JMIC 014-26).
  • September: the IEA reported a bombing of the Saudi East-West pipeline on 11 September. Oil flows through Hormuz rose to 10.9 million b/d for the month, and bypass exports to 5.6 million b/d (IEA, October 2026).
  • 15 October: IEA members had released about 330 million barrels, with around 100 million still to come (IEA).
  • 25 October: the JMIC kept the strait at SEVERE, counted 156 incidents since 1 March, and reported 101 US-facilitated transits over 22 to 24 October plus single-digit independent-tracking counts, against the 2025 baseline of about 138 a day. About 492 vessels were waiting outside (JMIC Update 108).

How to follow Hormuz traffic

GADUIN’s Strait of Hormuz page shows daily vessel transits against the strait’s normal level, the share of normal, the change from the week before and the latest news. Each day’s count is published with a delay. On these counts, Hormuz went from about 60–100 ships a day before the conflict to about 3–4 a day in March 2026. The chokepoints overview compares all chokepoints, the weekly transit counts page gives weekly totals, and shipping covers voyages. For how Hormuz ranks against Malacca, Suez and others, see the busiest shipping chokepoints.

Sources

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