IMF PortWatch
IMF PortWatch explained: chokepoint data, update times and the API
The free dataset that settles the shipping markets.
IMF PortWatch publishes a daily count of ships through 28 of the world's chokepoints, built from AIS transponder signals. It is free, it updates every Tuesday, and Polymarket and Kalshi settle their Hormuz, Bab el-Mandeb, Suez and Panama traffic markets on it. Here is where to find it, what it counts, when it lands, how it can change, and how to pull it yourself.
Fact file
IMF PortWatch at a glance
The chokepoint dataset as published, read on 9 November 2026.
- Publisher
- IMF, with the University of Oxford
- Built with Oxford's Environmental Change Institute and launched on 15 November 2023. Ship data are AIS signals supplied through the UN Global Platform.
- What it counts
- Daily transit calls
- Ships passing through each chokepoint, detected from satellite-received AIS signals and sorted by ship type.
- In market rules
- Transit calls, or 'Arrivals of Ships'
- Polymarket's rules use both names for the same PortWatch series. Kalshi's say transit calls.
- Chokepoints covered
- 28
- Including Hormuz, Bab el-Mandeb, Suez, Panama, Malacca, the Bosporus and the Cape of Good Hope.
- Ship types
- Five
- Container, dry bulk, general cargo, roll-on/roll-off and tanker. The daily total is their sum.
- Update
- Weekly, Tuesdays 9 AM Eastern
- Per PortWatch's data page. Each release adds the days since the last.
- History
- Daily since 1 January 2019
- For each chokepoint in the series.
- Also published
- Preliminary trade volumes
- Estimated cargo capacity passing, by ship type, labelled preliminary.
- Cost and access
- Free, no account needed
- Readable on the site, downloadable from the data page, and open to queries without a key.
- Known weakness
- AIS can be switched off or faked
- PortWatch's Hormuz page warns of GPS jamming, AIS spoofing and vessels going dark.
Sources: IMF PortWatch chokepoint pages, data page and daily chokepoint data, read 9 November 2026; IMF and University of Oxford launch materials.
Where to find PortWatch
PortWatch is free and needs no account. If a search result lands you on a PortWatch sign-in page, skip it and go straight to the pages below.
- PortWatch home: ports, chokepoints, trade estimates and disruption maps.
- Strait of Hormuz chokepoint page: the daily transit-call chart and PortWatch's own notes on the region. Other chokepoints follow the same pattern: chokepoint4 is Bab el-Mandeb, chokepoint1 the Suez Canal and chokepoint2 the Panama Canal.
- Data and methodology: the update schedule, the method, and links to each dataset, where you can download it or find its API links.
- The daily chokepoint table as an API: see pull it yourself below.
What a transit call is
A transit call is PortWatch's record of a ship passing through a chokepoint. PortWatch detects it from AIS, the radio transponders larger ships broadcast, as picked up by satellites, and sorts each ship by type.
The daily total for a chokepoint is the sum of five ship types: container, dry bulk, general cargo, roll-on/roll-off and tanker. PortWatch also estimates the cargo capacity passing, by type, and labels those trade figures preliminary.
Market rules borrow PortWatch's own words. Polymarket's call the series transit calls ('Arrivals of Ships'). The 7-day moving average they read is the average of the seven daily totals ending on a date, the figure behind the 'return to normal' and 'effectively closed' markets.
- Strait of Hormuz
- Bab el-Mandeb
- Suez Canal
2025: Strait of Hormuz 85.5, Bab el-Mandeb 33.5, Suez Canal 38.5
Show the numbers
| Transit calls a day | Strait of Hormuz | Bab el-Mandeb | Suez Canal |
|---|---|---|---|
| 2019 | 69.1 | 53.5 | 52.5 |
| 2020 | 73.6 | 54.5 | 52.8 |
| 2021 | 80.8 | 58.8 | 57.7 |
| 2022 | 93.5 | 67.1 | 67.1 |
| 2023 | 92.3 | 74.0 | 73.7 |
| 2024 | 91.1 | 32.5 | 39.6 |
| 2025 | 85.5 | 33.5 | 38.5 |
| Daily average, 2023 | Daily average, 2025 | Change | |
|---|---|---|---|
| Strait of Hormuz | 92.3 | 85.5 | Down 7% |
| Bab el-Mandeb | 74.0 | 33.5 | Down 55% |
| Suez Canal | 73.7 | 38.5 | Down 48% |
| Panama Canal | 30.2 | 31.1 | Up 3% |
The Red Sea attacks that began in late 2023 roughly halved daily traffic through Bab el-Mandeb and Suez by 2025. Hormuz fell to a handful of transit calls a day after the war began on 28 February 2026: its daily average for 2026, in data to 1 November, was 18.1.
When the data land
PortWatch's data page says the daily chokepoint series is updated weekly, on Tuesdays at 9 AM Eastern. Each release adds the days since the last one. For example, the release we read on Monday 9 November 2026 ran to Sunday 1 November.
So the newest day in the data is usually several days old, and the oldest new day in a release can be more than a week old. Markets that settle on PortWatch write that delay into their rules: Kalshi's weekly markets settle no earlier than the Tuesday after the week ends.
When a published day changes
PortWatch's trade figures are labelled preliminary, and published figures can change. The prediction markets that settle on PortWatch write rules for exactly that case.
- Polymarket. Its PortWatch markets count revisions made inside the market's window, never let a revision disqualify a value that already qualified, and ignore revisions made after the final date's data is published.
- Kalshi. The value is fixed when a market settles. The contract terms linked from each market set out how revisions are handled.
For the Strait of Hormuz, Aureum reads the PortWatch feed every morning and records every change to a day already published, so a restatement shows up as a restatement.
Where the counts go wrong
- Ships that switch AIS off are missed. PortWatch's Hormuz page warns of vessels going dark, GPS jamming and AIS spoofing in the region.
- Spoofed positions can put a ship where it is not, or hide one that is.
- A count of ships is not a count of oil. EIA estimates barrels separately, and warns that Hormuz AIS data have been "especially unreliable" since the end of February 2026.
None of this changes what the markets pay on. A market that settles on PortWatch pays on PortWatch's number, gaps and all.
Which markets settle on PortWatch
| Venue | What the markets ask | |
|---|---|---|
| Strait of Hormuz | Kalshi and Polymarket | Weekly totals, peak days, 7-day averages, and a return to normal at 60 |
| Bab el-Mandeb | Kalshi and Polymarket | Weekly totals, 'effectively closed' at a 7-day average of 10 or less, and a zero-ship day |
| Suez Canal | Kalshi | Weekly totals |
| Panama Canal | Kalshi and Polymarket | Weekly totals on Kalshi; 'effectively closed' at a 7-day average of 10 or less on Polymarket |
As listed on 9 November 2026. The Hormuz rules are set out in full on how the Hormuz markets settle, and the wider picture on prediction markets that settle on the physical world.
Pull it yourself: download and API
Open the chokepoint page
Each chokepoint has a page on portwatch.imf.org with a chart of daily transit calls. The Strait of Hormuz page is one.
Download the daily series
The data page links to the daily chokepoint series, which you can download as a file. It is the series the markets read.
Or query it directly
The daily chokepoint table is a public ArcGIS feature service, Daily_Chokepoints_Data, and needs no key. This query returns the latest seven Hormuz days as JSON.
Each row carries the date, the chokepoint id (portid), the daily total (n_total), a count for each ship type and the preliminary capacity estimates. Swap chokepoint6 for another id to read a different chokepoint.
Note the last date in the data
Check which day the data run to before you compare them with a tracker or a headline.
Compute what the market computes
Sum Monday to Sunday for the weekly markets. Average the seven daily totals ending on a date for the 'normal' and 'closed' markets.
IMF PortWatch: questions and answers
See the chokepoints between Tuesdays
Aureum's Hormuz and Bab el-Mandeb boards count the ships that cross each gate line every day, from their transponders, so the days PortWatch has not yet published are not a blank. Free while Aureum is in beta.