Hormuz Transit Counts: US Claims 40 Ships a Day, Kpler and Lloyd's List See About 12

Six months into the war, nobody can agree on how many ships are getting through the Strait of Hormuz. Washington says traffic is climbing and the lanes are clear. Tehran says the strait is shut to anyone it hasn’t approved. The commercial trackers, the ones insurers and oil desks pay for, land a lot closer to Tehran’s picture.

The gap is wide. On 1 September two US officials said 40 commercial ships had crossed under naval escort carrying roughly 18 million barrels of oil, a wartime record. Kpler counted 11 vessels that day.

So which number is right? The honest answer is that they’re measuring different things, and some of the claims fail a basic arithmetic test.

Every Figure on the Table

Here is what each side has put out over the past three weeks.

Source Date or period Figure
Trump 31 Aug About 30 ships a night crossing with US Navy help
Bessent (Treasury) 31 Aug 15-17 million barrels that day; “at least 10 million” on a typical day
US officials (to CNN) 1 Sep 40 commercial ships, about 18 million barrels
Kpler 31 Aug 5 vessels
Kpler 1 Sep 11 vessels
Kpler 2 Sep 6 vessels
Kpler Trailing 10-day average, early Sep 13 vessels a day
Lloyd’s List Intelligence 17-23 Aug About 14 non-Iranian-linked ships a day
Lloyd’s List Intelligence 26 Aug - 1 Sep About 12 transits a day
IMF PortWatch March to late August average 7 vessels a day
IMF PortWatch 6 Sep 6 transits

Two private trackers using different methods land within one ship a day of each other. The US figure is roughly three times theirs.

The Baseline Moves Too

Before the war, the usual estimate was around 100 ships and 20 million barrels a day through the strait. The IEA’s 2025 average was also 20 million barrels a day of crude and products, about a quarter of all seaborne oil trade. Some live trackers use a lower vessel baseline, nearer 85 a day, because they filter out smaller traffic.

That spread matters when you express current traffic as a share of normal.

Daily figure Share of 100/day baseline Share of 85/day baseline
US claim, 40 ships 40% 47%
Kpler 10-day average, 13 13% 15%
Lloyd’s List, 12 12% 14%
PortWatch wartime average, 7 7% 8%

Pick the generous baseline and the US claim still has the strait at under half capacity. Pick the tracker data and it’s running at one-seventh or less. Either way, “open” is doing heavy lifting.

The Hull Test

Ship counts are arguable. Barrels are easier to check, because barrels need hulls and hulls have fixed sizes.

Vessel class Typical cargo, barrels
VLCC About 2,000,000
Suezmax About 1,000,000
Aframax / LR2 600,000 - 750,000
LR1 About 450,000
MR product tanker About 300,000

Now run the US oil claims against the tracked vessel counts. Assume the most favourable case possible: every vessel Kpler saw was a fully laden VLCC heading out.

Day Claimed barrels Vessels tracked by Kpler Maximum if all were laden VLCCs Gap
31 Aug 15-17 million 5 10 million 5-7 million short, or 3-4 extra VLCCs nobody logged
1 Sep 18 million 11 22 million Fits only if 9 of the 11 were laden outbound VLCCs

The 31 August figure can’t be squared with the tracked fleet at all. Kpler’s count covers both directions and includes non-tankers. The real ceiling is lower than 10 million.

The 1 September claim is odd in a different way. Eighteen million barrels spread over 40 ships works out to 450,000 barrels a ship, which is an LR1 cargo. That’s plausible for a convoy of mid-size product tankers. It’s much harder to reconcile with a day when commercial trackers saw 11 hulls in total.

There is one legitimate escape hatch. Dark transits (ships crossing with AIS switched off) don’t show up in real time. Lloyd’s List has said its latest numbers may be incomplete for exactly that reason. Drewry says that by late August most Hormuz crossings were classed as dark or unknown by route, with confirmed movements backdated later. A few dark VLCCs would close part of the 31 August gap. They wouldn’t close it by 3 or 4 ships without someone noticing.

Who Counts What

Most of the disagreement comes down to definitions.

Counter What gets counted What gets filtered out
Lloyd’s List Intelligence Cargo-carrying vessels over 10,000 dwt Small craft and anything not carrying cargo
Kpler Vessels meeting size or cargo thresholds Auxiliaries, tugs, dhows, small coastal traffic
US military Plausibly anything moving under or near naval protection, including naval auxiliaries, offshore support vessels, tugs and dhows; also uses satellite and airborne sensors plus its own convoy manifests Unknown, method not published
Iran Only pre-approved vessels in its designated channels count as legitimate Anything on the southern route, which it calls illegal

The US has sensor coverage no commercial firm can match, so its count could genuinely include ships the trackers miss. It also has every reason to count tugs and escorts if nobody asks. Iran has the mirror-image incentive. Both governments have made control of the strait the central claim of the war, and both are publishing numbers that support it.

What Would Settle It

Backdated revisions. Lloyd’s List and Kpler both re-tally once dark transits are confirmed, usually with a lag of a week or two. If the revised late-August and early-September averages climb toward 20 a day, Washington’s counting was loose but grounded in real movement. If they stay in the low teens, the 40-ship day was a talking point.

Meanwhile the risk picture hasn’t moved much. The Joint Maritime Information Center’s 1 September advisory kept Hormuz at “severe”, citing drifting or uncharted mines despite CENTCOM saying the lanes had been swept. PortWatch logged 6 transits on 6 September. On 12 September UKMTO reported a vessel struck by an unknown projectile near Limah, on the Omani side.

Six ships is not a reopened strait.

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