A plain-English guide to shipping chokepoints and oil supply risk.

Roughly 60 percent of world oil moves by sea. Those seaborne barrels do not travel evenly across the ocean; they funnel through five narrow passages where a small number of ships pass a given point every hour. Any threat to any of those passages is what oil traders call a chokepoint premium. This piece is the framework for what the five chokepoints are, how much oil moves through each, what a disruption at each historically costs the price, and why the current Iran story reaches oil through this specific channel.

The paired analysis today reads Friday's Brent +3 percent move on Iran retaliation as chokepoint-premium repricing. This piece explains why that channel matters more than Iran's own barrel production, and why the Red Sea specifically was named in the Houthi-preparedness reports.

Why chokepoints matter

The market for oil is roughly 100 million barrels per day. About 60 million of those barrels move by sea (the rest by pipeline or by rail, or are consumed where produced). Of the 60 million seaborne barrels, a substantial share passes through one of five physical bottlenecks on the way from producer to consumer.

A pipeline can be damaged or blocked; that removes the barrels for the duration of the repair. A single chokepoint disruption can remove several pipelines' worth of oil at once, and often for a longer period, because reflagging or rerouting ships around a blocked passage adds weeks of transit and can exceed the physical fleet's capacity to absorb the detour.

The market prices the risk of a disruption, not just the disruption itself. That means chokepoint premium trades on threats, not only on actual closures. When tanker insurance rates spike for a given route, the physical price of oil for prompt delivery via that route rises alongside. The pattern is: threat headline → insurance premium rise → tanker rerouting → prompt oil price rise. Each step compounds the next.

The five chokepoints

Strait of Hormuz

The 21-nautical-mile-wide passage between Iran and Oman that carries oil out of the Persian Gulf. Roughly 20 million barrels per day of seaborne oil pass through, which is about 20 percent of global oil consumption and roughly a third of seaborne oil. Saudi Arabia, UAE, Iraq, Kuwait, and Qatar all use Hormuz as their primary export outlet. Iran itself sits on the north shore. There is no fully commercial-scale alternate route: Saudi Arabia and UAE have some pipeline capacity to the Red Sea, but the total bypass capacity is roughly 6 million barrels per day against the 20 million Hormuz-borne. A closure would strand two-thirds of Persian Gulf export capacity.

Historically, Hormuz has never been closed. It has been threatened many times, most notably during the 1980s Iran-Iraq tanker war and repeatedly in the 2019-2020 period around US-Iran tensions. The market prices a Hormuz-threat premium on every US-Iran escalation cycle because the physical geography does not change.

Bab-el-Mandeb and the Red Sea

The 18-mile-wide passage between Yemen and Djibouti at the southern end of the Red Sea. Roughly 6-7 million barrels per day of oil pass through, plus a similar volume of refined products and LNG, and (crucially) a large share of the world's containerised trade heading to Europe from Asia via Suez. The Red Sea corridor (Bab-el-Mandeb at the south, Suez at the north) is the primary shortest-distance route between Asia and Europe. The alternative is around the Cape of Good Hope, which adds roughly 10-14 days of transit each way.

The 2023-2024 Houthi attacks on Red Sea shipping demonstrated that a non-state actor with anti-ship missiles can shift the global tanker map. Major shipping companies rerouted around the Cape for most of 2024, taking freight rates on the affected routes from roughly $2,000 per container up to more than $8,000 at peak, and pushing Brent premiums of approximately $4-6 per barrel that took months to unwind. The Houthi angle is why the Friday July 17 reports specifically named Red Sea shipping preparedness as an Iran-directed response option. Hormuz threat plus Red Sea threat is a much wider disruption surface than either alone.

Suez Canal

The northern end of the Red Sea route into the Mediterranean. Roughly 6 percent of world seaborne oil and about 10 percent of world LNG pass through, plus the container flows already noted. Suez is a single-file passage: the 2021 Ever Given grounding closed the canal for six days and produced a world-shipping backlog that took weeks to clear. The disruption cost approximately $9 billion of daily trade over those six days and pushed Brent approximately $3 per barrel higher on the first trading day.

Suez is a physical rather than geopolitical chokepoint. Egypt has an economic interest in keeping it open (canal fees are approximately 2 percent of Egyptian GDP), so the tail risk is accident or non-state disruption rather than state-level closure.

Strait of Malacca

The 500-mile-long passage between Malaysia and Indonesia carrying oil eastward from the Middle East and Africa to China, Japan, South Korea and the rest of East Asia. Roughly 25 million barrels per day pass through, which is more than Hormuz. Malacca is wide enough that a state-level closure is essentially unavailable to any coastal power, and the alternative (Lombok and Sunda straits) exists but adds days to transit. The chokepoint premium here is measured in piracy risk and, in the longer view, in China-Taiwan contingency planning.

Malacca does not currently price a live premium. It sits in every long-horizon energy-security analysis because a China-Taiwan disruption would touch it, but that is a tail risk not a live channel.

Turkish Straits (Bosporus / Dardanelles)

The passage from the Black Sea to the Mediterranean through Istanbul. Approximately 3 million barrels per day of oil, roughly a third of which is Russian, plus grain flows that make it materially relevant to the grain-complex chain as well. Turkey retains legal control under the Montreux Convention and has discretion over warship transit during wartime, which became a live constraint in 2022-2024. Oil throughput is smaller than Hormuz or Malacca but the concentration of Russian barrels makes it strategically important for the sanctions-and-price-cap channel.

How the market prices chokepoint risk

The visible signals are three:

• Prompt Brent premium over WTI. Brent is seaborne-priced (physical delivery at Sullom Voe, Scotland, sourced from North Sea grades and the wider ICE Brent basket that includes some Mid-East grades). WTI is landlocked at Cushing, Oklahoma. A seaborne supply threat widens the Brent-WTI spread. Historically the spread runs at $2-3; on a chokepoint scare, it widens to $5-8. Friday's Brent close of $86.75 against WTI's approximate $84.20 corresponds to a spread of roughly $2.55, wider than pre-shock but not extreme.
• Options skew on Brent calls. When the market expects a further right-tail supply shock, out-of-the-money call skew steepens relative to put skew. This shows up in the Brent CVX (Cboe Volatility of Brent Crude) as well as in the specific-strike implied vol surface. Traders track the skew as a leading indicator of physical premium repricing.
• Tanker rates on affected routes. VLCC and Suezmax spot rates on Mid-East-to-Asia and Mid-East-to-Europe voyages rise on threat headlines, often by a factor of two or three within a week. War risk insurance premiums layer on top; combined shipping cost per barrel can shift by $2-5 in a matter of days.

The half-life question

Chokepoint premiums decay when the market decides the threat has been priced in and the physical flow has not been interrupted. Historically the decay is faster than the initial spike: full round-trip within four to eight weeks is the modal path. But when the threat compounds (a second escalation event lands while the first premium is still in the tape), the decay pauses and the premium re-extends. That is what the July 13 to July 17 shape looks like in the Brent tape: initial +9 percent on the US strike, brief consolidation, second +3 percent on Iran retaliation.

A durable chokepoint disruption (any of the five passages materially closed or restricted for weeks) would put Brent into a $95-plus print and hold it there until either a demand-destruction response develops or a diplomatic de-escalation is credible. Short of that, each threat cycle produces a repricing that partially fades until the next event.

What to watch alongside a chokepoint story

• Reference: oil markets end to end. Curve structure, OPEC+ band, geopolitical premium overlay.
• Reference: oil inflation transmission. When Brent breaks above the level that materially moves headline CPI, the story is no longer just about oil.
• Baltic Dirty Tanker Index and Baltic Clean Tanker Index for the shipping-cost read.
• Reuters and Kpler weekly loadings data by origin port and destination for the physical-flow read.
• Insurance markets: Lloyd's list of high-risk designated areas, war risk insurance premium surveys.

The chokepoint premium is one of the highest-signal parts of the oil market because the physical geography does not change. When a threat lands on a specific passage, the market has a reasonably good historical base rate for how much of a premium to price. What varies is the credibility of the threat and the duration of the risk. Both are readable from headline flow and from the derivatives-market signals above.