About This Site & Methodology

What this is

The Strait of Hormuz Ship Monitor is an independent, free dashboard that tracks commercial shipping through the Strait of Hormuz — the world's most important oil chokepoint — in near real time. It detects vessel crossings, estimates oil and gas export volumes, classifies transit routes, and flags sanctioned vessels, with historical charts for trend analysis.

It is built for anyone who needs a quick, factual read on what is physically moving through the strait: energy analysts, commodity traders, journalists, researchers, and the generally curious. It is not affiliated with any government, data vendor, or trading firm.

Why the Strait of Hormuz matters

The strait is a narrow waterway — about 21 nautical miles at its narrowest — connecting the Persian Gulf to the Gulf of Oman and the open ocean. Roughly a fifth of the world's petroleum and around a quarter of global liquefied natural gas trade passes through it. There is no meaningful seaborne alternative: pipeline detours can replace only a fraction of the flow. Ships transit through designated traffic-separation lanes, each just a few kilometers wide, making the strait uniquely sensitive to disruption — and making its daily traffic a leading indicator watched by energy markets worldwide.

Where is the Strait of Hormuz?

The Strait of Hormuz lies between Iran and the Arabian Peninsula, around 26.6°N, 56.4°E. It is the only sea passage out of the Persian Gulf: to its west are the Gulf ports of Iraq, Kuwait, Saudi Arabia, Bahrain, Qatar, the United Arab Emirates and Iran; to its east the Gulf of Oman opens into the Arabian Sea and the Indian Ocean.

The northern shore is Iran, with the port of Bandar Abbas and the islands of Qeshm, Hormuz and Larak. The southern shore is the Musandam Peninsula, an exclave of Oman separated from the rest of the country by the UAE, with Khasab as its main town. At the narrowest point, between Larak Island and Oman's Quoin Islands, the strait is about 21 nautical miles (39 km) wide.

Ships follow a traffic separation scheme in Omani waters off Musandam: one lane into the Gulf and one out of it, each about 2 nautical miles wide, with a 2-mile buffer between them. The tracks on the map show a second route closer to the Iranian islands; this site labels every transit with the path it took, Oman or Iran (see How crossings are detected below).

Two terminals on the Gulf of Oman let oil leave without passing through the strait: Fujairah in the UAE, at the end of the Habshan–Fujairah crude pipeline, and Jask in Iran, at the end of the Goreh–Jask line (see Can oil bypass the Strait of Hormuz?). Inside the Gulf, Abu Musa and the Greater and Lesser Tunbs are held by Iran and claimed by the UAE; Dubai and Ras al-Khaimah are the UAE's nearest large ports.

Where the data comes from

Commercial vessels above certain size thresholds are required to broadcast their identity, position, course, and speed via AIS (Automatic Identification System) transponders. This site collects AIS position reports from publicly available sources approximately every 30 minutes, typically observing around 4,000 vessels per cycle across the Persian Gulf, the strait itself, and the Gulf of Oman. Vessel characteristics (type, deadweight tonnage, flag, destination) come from the same public data, enriched with public ship registries.

Position history is retained for 365 days (the most recent 30 in full detail, older reports compacted; positions from 9 April to 19 May 2026 were not preserved); detected crossings and daily aggregates are retained indefinitely.

How crossings are detected

The monitored area is divided into three zones: the Persian Gulf, the strait area (which also contains major anchorages such as Bandar Abbas and Qeshm), and the Gulf of Oman. A crossing is recorded when a vessel's observed track moves from one gulf to the other — whether we see it transit the strait fix by fix, or it disappears on one side and reappears on the other (common during coverage gaps and transponder dark periods). There is no limit on how long the ship may be unseen in between: a tanker last seen inside the Gulf and next seen off India still counts. A crossing found after more than a day without a signal is dated back to its estimated passage, from the sea distance to the strait at 12 knots.

The dashboard's 24-hour and 7-day figures count a crossing from when it was found, so a ship that crossed dark adds to the figures on the day it reappears. Daily charts and the monthly statistics file it on its estimated date, and a crossing found more than 15 days after that date counts only there.

Two refinements matter in practice:

• Anchorage calls. The Bandar Abbas / Qeshm anchorages sit inside the strait area. A vessel that arrives from the Gulf of Oman, dwells at anchor for more than 24 hours, and departs the way it came has still transited the strait's narrows twice; we count one crossing in the direction of the departure leg, provided its track actually crossed the narrows.
• Route classification. Completed transits are classified by which side of the strait they favored — the Oman-side or Iran-side lanes — where the track allows it; transits observed only as a disappearance/reappearance are labeled unidentified.

How the oil and gas estimates work

The headline export figures are capacity-based estimates, not measured cargoes:

applied to outbound tanker crossings only, split into crude (crude oil tankers) and products (oil products and oil/chemical tankers) by vessel category. LNG/LPG volumes are estimated the same way from gas-carrier crossings, in tonnes (DWT × 0.95). Inbound tankers (typically in ballast) are counted as crossings but contribute nothing to export volumes.

The “Oil leaving the Gulf” table

The table on the dashboard adds the routes that carry Gulf oil out without crossing the strait. Each row shows the selected period (24 hours by default), the average per day over the last 7 days, and a pre-war daily baseline. Each tanker counts as a full cargo, using the formula above.

• Through the strait: the outbound tanker crossings described above. Pre-war: 20 million barrels a day, the oil that crossed Hormuz before the 2026 war.
• Fujairah bypass: crude loaded at Fujairah, at the end of the Habshan–Fujairah pipeline (see the bypass guide). A crude tanker of 60,000 DWT or more that moors at Fujairah's crude berths for at least 8 hours and then leaves counts as one loading, dated the day it left. A tanker under 120,000 DWT counts only at the offshore buoys; at the port jetties it may be loading fuel oil, not crude. A tanker that crossed the strait outbound in the 30 days before is already counted in the strait row, and one that sails into the Gulf within 10 days is left out. Pre-war: 1.2 million barrels a day, the 2025 average.
• Ship-to-ship exports (estimate): oil that tankers took from storage tankers in the Gulf of Oman and carried out of the region, counting only barrels that no other row holds (method below). There is no pre-war figure, because we have only seen these transfers since 11 October 2026.
• Total measured: the sum of the three rows above, all from our own AIS data.
• Saudi East–West (reported): crude loaded at Yanbu on the Red Sea, at the end of Saudi Arabia's East–West pipeline. This row is not measured here: Yanbu is outside our coverage and the loading tankers there keep their AIS off. It shows the latest published figure, Kpler's export count reported in the press, updated by hand, with its date in the table's notes. Pre-war: 1.0 million barrels a day.
• Total: total measured plus the reported Saudi figure.

Iran's Goreh–Jask pipeline has no row: the tankers off Jask sit there for weeks as floating storage, and we see no loadings there to count. Oman's own exports from Mina al Fahal are not a bypass and are left out.

Dry cargo

The dry-cargo tile counts merchant cargo ships crossing the strait in both directions: bulk carriers, container ships, general cargo, ro-ro and vehicle carriers, reefers and similar. Tankers are left out because they are already in the oil and LNG/LPG figures. Unlike tankers, dry cargo moves loaded both ways: grain and ore come in, while fertiliser and sulphur go out. AIS gives no draught in our data, so each crossing carries a fixed share of its deadweight:

Both shares come from comparing our crossings with IMF PortWatch, which estimates cargo per transit from each ship's draught, for September and October 2026.

Known limitations — read this before trading on the numbers

Honest measurement requires stating what this system cannot see:

1. AIS is self-reported and can be switched off. Sanctions-evading ("shadow fleet") vessels routinely go dark. A dark transit is invisible until the vessel reappears on the other side, and is never counted if it does not. Since mid-2026 most large tankers have crossed with AIS off, so the strait row shows a small part of the oil that commercial trackers using satellite imagery and port data report.
2. Electronic interference. GPS jamming and spoofing around the strait, reported intermittently since mid-2025, has been widespread since July 2026 and degrades position quality for all vessels. Read our figures as conservative lower bounds. The jamming guide explains the mechanics.
3. Laden status is assumed, not observed. The DWT-based formula assumes outbound tankers are ~95% laden. Some are not; conversely, some cargo moves on vessels our category filter treats conservatively.
4. Category granularity. Public vessel-type data is imperfect; a small share of vessels is classified from partial information.
5. Coverage varies. Terrestrial AIS reception in parts of the strait fluctuates; the detection logic is designed to recover crossings from partial tracks, but no method recovers what was never observed.

For these reasons the site's figures are best used as a directionally reliable, methodologically consistent index of strait activity — ideal for spotting changes and trends — rather than as audited trade statistics.

Storage, supply and ship-to-ship analysis

Beyond the live tracker, the site maintains three analytical modules: oil storage, supply and demand, and STS Watch (beta). The first two draw on official statistics rather than AIS; STS Watch is built from our own AIS positions. Every figure carries its source and refresh date on the page.

• Oil storage. Reported inventory levels aggregated across countries: EIA weekly data for the United States (commercial crude, the Strategic Petroleum Reserve, gasoline, distillate, Cushing), the Petroleum Association of Japan and JODI for Japan (refiner stocks and the national strategic reserve), Eurostat for the EU27 (crude and total oil, with preliminary months summed from reporting member states), and JODI for Saudi Arabia, India, South Korea and the United Kingdom. Series in tonnes are converted at 7.33 bbl/t. Subset series are never stacked on their supersets. Collectors run daily; monthly sources typically lag one to three months.
• Supply and demand. World production and consumption, Gulf producers' output, OPEC and non-OPEC supply, OECD commercial stocks and days of cover, and US product consumption from the U.S. Energy Information Administration's Short-Term Energy Outlook (STEO), plus US crude imports from Persian Gulf countries from EIA's Petroleum Supply Monthly. STEO is re-downloaded daily; months after the latest observed month are EIA estimates and are always drawn dashed. The supply-shortfall decomposition (demand destruction, storage draw, foregone stock build) is an exact accounting identity on those series, not a model.
• Ship-to-ship transfers. An AIS-behaviour analysis of tankers that loiter in the Gulf of Oman without having transited the strait, pair-matched against crude tankers that went dark from a Persian Gulf position and resurfaced at the loiter spot. Volumes assume departures are laden at 95% of deadweight and are therefore upper bounds; matching is circumstantial evidence, not proof, and the underlying report is rebuilt daily from the last 90 days of positions. The full method is below.

All EIA products are U.S. government works in the public domain and are reproduced with attribution to the U.S. Energy Information Administration; JODI, PAJ and Eurostat data are used under their respective open-data terms.

STS Watch: how ship-to-ship transfers are estimated (beta)

STS Watch looks for oil that leaves the Gulf without ever showing up as a strait crossing. The pattern it tests for: a tanker crosses Hormuz with its AIS transponder off, meets a second tanker that is waiting in the Gulf of Oman with AIS on, and transfers its cargo ship-to-ship (STS). The second tanker then sails away looking like any other ship that never entered the Gulf. The page finds those waiting tankers (receivers), tries to pair each one with a tanker that went dark at the right time and place (a provider), and estimates how much oil the receivers could have carried away.

Step 1: candidate receivers

A receiver is a crude or product tanker that, within the 90 days of positions we keep:

• was seen in the Gulf of Oman;
• was never seen in the Persian Gulf or in the strait itself; and
• has no detected strait crossing in our records.

In other words, it had no visible way to load Gulf oil at a Gulf terminal.

Step 2: loitering away from a berth

For each candidate we look for loiter episodes: at least 48 hours spent within a 12 km radius, with a median speed of 2 knots or less, and positions in at least 40% of the half-hour polling slots (so a ship that simply went silent does not look stationary). Episodes at a port are dropped as ordinary port calls: within 12 km of Fujairah, Sohar, Muscat / Mina al Fahal or Sur / Qalhat, 10 km of Khor Fakkan, or 15 km of Iran's Jask terminal. A ship with at least one remaining episode counts as a receiver.

Step 3: what happened next

• Exited: after its last loiter the ship moved more than 25 km from the spot or reached 6 knots, and its latest position is outside the Gulf of Oman. The page labels where it went: toward India, the Arabian Sea, the Red Sea direction, or elsewhere.
• Went dark: no signal for more than four days after the loiter.
• In Gulf: still in the Gulf of Oman, staging or waiting.

Step 4: attribution

Each receiver gets one of three labels:

• STS match: a crude tanker that was in the Persian Gulf or the strait, and that has no detected crossing, went dark for at least 24 hours starting from a position west of the strait. Four conditions must all hold:
  • sailing from where it went dark at about 12 knots, it could have reached the loiter spot and still spent at least 12 hours there during the loiter;
  • its dark gap started and ended within the loiter window, give or take 24 hours;
  • it reappeared within 30 km of the loiter spot;
  • it did not reappear at a terminal's berths.
  Requiring the provider to have no detected crossing means its oil is not already counted in the dashboard's outbound figures. The 24-hour minimum gap and the reappearance test filter out the short gaps that GPS jamming produces for every ship.
• Jask: no STS match, but the ship loitered within 120 km of Iran's Jask pipeline terminal. That points to lifting from the Goreh–Jask pipeline, which also bypasses the strait.
• Unattributed: a receiver-like loiter with neither of the above.

Step 5: barrels

Volumes use the same capacity formula as the rest of the site:

It applies only to crude tankers of at least 25,000 DWT. Product tankers are listed as cases but carry no volume. An exited ship's volume is booked to the month its last loiter ended, and the monthly chart stacks those volumes by attribution. Ships still in the Gulf are summed as afloat capacity, and ships that went dark as dark capacity. Neither is counted as exported.

Reading the numbers

• Upper bounds. AIS does not report how much cargo a ship carries, so every departing receiver is assumed laden. Some leave partly loaded or empty.
• Circumstantial, not proof. Tankers also wait offshore for orders, bunkers, crew changes or a berth, especially off Fujairah. A match is a timing and geography pattern, and no label on the page is an allegation against a named vessel.
• What it cannot see. Transfers between two ships that both keep AIS off are invisible to this method.
• Rolling window. The report is rebuilt every day at 03:20 UTC from the last 90 days of positions, so the oldest month is partial and its total shrinks as positions age out.
• Not the dashboard's figure. STS Watch volumes are never added to the dashboard. They are a separate, explicitly uncertain upper bound. The dashboard's “Ship-to-ship exports” row uses a stricter method, described next, so it is much smaller.

Each case on the page opens a map of its track: the approach in blue, the estimated STS window in orange, the exit transit in green, and the region's oil loading terminals for context.

The dashboard's ship-to-ship exports row

STS Watch asks where oil could have gone; the dashboard row counts only transfers we saw happen, and only barrels that are not already in the table. The two answer different questions:

• Transfers seen. Two oil tankers of at least 20,000 DWT each, within 150 metres of each other, both under 2 knots, for at least 6 hours, in the Gulf of Oman and away from the Fujairah and Sohar berths. We see these only since 11 October 2026, when the site began reading more detailed map views.
• Who gave and who took. Roles come from what each tanker did next: one that sailed out of the region (past Ras al Hadd, into the Arabian Sea) took the oil; one that went back into the Gulf to refill gave it. A taker that has not left the region within 10 days of the transfer is not counted.
• No double counting. Each tanker keeps a ledger of barrels already counted: it fills at an outbound strait crossing or a counted Fujairah loading and empties when the ship goes back into the Gulf. Counted barrels move first in each transfer, so only the part of a departing tanker's cargo that no row holds yet is added, on the day it leaves.
• Size. A transfer moves the smaller ship's full cargo (DWT × 0.95 × 7.33). As everywhere on the site, this assumes ships are laden, so it is an estimate.

In practice most of this oil comes from a few large tankers that have sat in the Gulf of Oman as storage for months and load departing tankers bound for Asia. STS Watch's larger figure also includes tankers that only waited at an anchorage, and oil that was already counted at the strait or Fujairah.

Updates and availability

Data refreshes roughly every 30 minutes around the clock. Daily chart buckets use UTC. The underlying data is available through a free JSON API (see the API documentation). Our data may be reused, including commercially, under CC BY 4.0, with attribution to hormuz.data-tracking.net. Third-party data shown on the site (EIA, JODI, PAJ, Eurostat, UKMTO) stays under its own terms.

Independence and contact

The site is operated independently. It carries advertising and may offer optional email updates to cover infrastructure costs; neither influences the data or methodology. Corrections, questions, and suggestions are welcome via the feedback form — the site improves regularly based on reader reports. See also our FAQ, the monthly crossing statistics, the explainer guides, and our Privacy Policy.

Nothing on this site is investment advice, and none of it should be used for navigation.