Strait of Hormuz — Frequently Asked Questions
How much oil passes through the Strait of Hormuz per day?
Before the 2026 Iran war, roughly 20–21 million barrels of crude oil, condensate and refined products transited the strait every day — about a fifth of global petroleum consumption. Wartime disruption, GPS/AIS jamming and rerouting through pipelines have sharply reduced seaborne flows. The live dashboard publishes an AIS-derived estimate of current outbound volumes, updated every 30 minutes, and the monthly statistics archive tracks how flows have evolved.
How wide is the Strait of Hormuz?
About 21 nautical miles (~33 km) at its narrowest point, between Iran and Oman's Musandam Peninsula. Ships use a Traffic Separation Scheme: a 2-mile-wide inbound lane, a 2-mile-wide outbound lane, and a 2-mile buffer between them.
Why is the Strait of Hormuz so important?
It is the only sea passage from the Persian Gulf to the open ocean. Exports from Saudi Arabia, Iraq, Kuwait, the UAE, Qatar and Iran must either sail through it or move by pipeline. It also carries roughly a fifth of global LNG trade, almost all of it from Qatar. No other chokepoint concentrates as much of the world's energy supply in one place.
Can Iran close the Strait of Hormuz?
Iran can disrupt the strait — mines, missiles, drones and harassment of shipping, as the 2026 war has shown — and can raise insurance and freight costs enough to deter much of the traffic. A complete, sustained closure is much harder: the shipping lanes run largely through Omani territorial waters, and keeping the strait open is a core mission of Western naval forces in the region. Disruption, rather than hermetic closure, is the realistic threat — and it is visible in the crossing statistics. Whether exporters could route around a closure is covered in Can oil bypass the strait?
What is AIS and how does ship tracking work?
AIS (Automatic Identification System) is a transponder system that broadcasts a ship's identity, position, course and speed. Coastal receivers and satellites collect these broadcasts — that is how every live ship-tracking map works. This site polls AIS positions for the Gulf region every 30 minutes and detects vessels crossing between the Persian Gulf and the Gulf of Oman zones; the methodology page has the full detail.
Why do ships disappear from tracking?
Three main reasons: deliberate transponder shutdowns (“going dark”, common among sanctioned-oil carriers), widespread GPS/AIS jamming and spoofing linked to the conflict, and plain gaps in receiver coverage. Since mid-2026, jamming has degraded position reporting across the strait — crossing counts derived from AIS should be read as conservative lower bounds. The jamming guide explains the mechanics and what spoofed tracks look like.
How is the oil export volume estimated here?
Each outbound crossing by a crude, product or chemical tanker contributes deadweight tonnage × 95% load factor × 7.33 barrels per tonne — the standard crude conversion. It is an AIS-derived proxy for gross seaborne outflow, not customs data, and it undercounts whenever ships transit dark. Full formula and caveats on the methodology page.
What is a VLCC?
A Very Large Crude Carrier — a tanker of roughly 180,000–320,000 deadweight tonnes carrying about 2 million barrels of crude. VLCCs are the workhorses of Gulf oil exports; smaller classes include Suezmax (~1M bbl) and Aframax (~700k bbl), while product and chemical tankers are smaller still. The live tracker labels each crossing with its vessel class and estimated barrels. The full ladder from product tankers to ULCCs is in Tanker classes explained.
Which countries depend most on the strait?
On the export side: Saudi Arabia, Iraq, Kuwait, the UAE, Qatar and Iran. On the import side, most Hormuz crude goes to Asia — China, India, Japan and South Korea are the largest buyers. Only Saudi Arabia and the UAE operate pipelines that can bypass the strait, with far less capacity than normal seaborne flow.
Is this data free? Is there an API?
Yes. The dashboard is free and current positions, crossing statistics and the ship directory are available through a free JSON API — no key, no registration. Data may be reused with attribution under CC BY 4.0.
Is the Strait of Hormuz closed right now?
Not physically, but seaborne traffic has collapsed. Since the 2026 Iran war began, this monitor has detected a fraction of the strait's normal crossings, and estimated seaborne oil outflow has run well under a fifth of the roughly 20 million barrels a day that moved before the war. The live tracker shows what is crossing right now and the monthly statistics show how the flow has evolved. Because GPS and AIS jamming hide some transits, detected figures are lower bounds: few ships seen does not mean no ships.
How many ships pass through the Strait of Hormuz per day?
Before the war, industry estimates put traffic at well over a hundred vessel transits a day across all ship types. In 2026 this monitor detects far fewer: August 2026 averaged about 18 detected crossings a day, and most months since March 2026 have been in a similar range. Detection depends on AIS, so the true count is higher than the detected one whenever jamming is active.
Why do the numbers here differ from other sources?
Three reasons. Coverage: this monitor uses terrestrial AIS from one provider and only sees ships that transmit, while commercial services blend satellite AIS, port data and analyst estimates. Method: a crossing here is a detected zone transition between the Persian Gulf and the Gulf of Oman, and oil volumes are deadweight-based estimates rather than cargo manifests. Timing: figures update every 30 minutes and are revised as late positions arrive. Treat them as a consistent, transparent lower bound rather than an official statistic; the methodology page has the details.
What are dark ships and ship-to-ship transfers?
A dark ship switches off or spoofs its AIS transponder to hide its movements, a practice common among sanctioned-oil carriers. A ship-to-ship (STS) transfer moves cargo between two tankers at sea, often in anchorages outside normal port reporting, so oil can change hands and identity before it sails on. Both make seaborne flows harder to count. The jamming guide explains what these tracks look like, and the dashboard flags matches against sanctions lists.
How long can oil stocks cover the shortfall?
Importers are drawing down inventories to replace lost Gulf supply. The Oil Storage page tracks reported stocks in the US, EU, Japan and other importers against their February 2026 pre-war levels, and the Supply & Demand page shows how much of the missing supply has been met by storage draws versus lower consumption, using EIA's monthly outlook. OECD commercial stocks amount to roughly two months of consumption, but strategic reserves, pipeline bypasses and demand destruction all stretch that figure. Both pages refresh daily as new data is published.