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What is schedule reliability in container shipping?

By Toni Tan · · 9 min read

Schedule reliability is the share of container vessel arrivals that reach a port on time against the schedule the carrier published for that service. It answers a question a headline transit time cannot: if the timetable says the vessel calls on Tuesday, how often does that actually happen? Sea-Intelligence publishes the most widely cited series in its monthly Global Liner Performance report, which covers 34 trade lanes and more than 60 carriers (Sea-Intelligence); Xeneta publishes a separate schedule reliability scorecard. Neither is a promise from the carrier, and the two are not interchangeable, so follow one provider’s series over time rather than comparing percentages across providers.

Two numbers travel together, and reading only one of them misleads. The first is the share of arrivals counted as on time. The second is the average delay for the arrivals that were late. In June 2026 global schedule reliability fell 1.9 percentage points to 62.6%, yet the average late arrival improved by 0.34 days to 5.31 days, so fewer vessels arrived on time but the ones that missed did so by less (Sea-Intelligence). A reader watching only the headline would have drawn the wrong conclusion about that month.

How schedule reliability is measured

Providers track vessel calls against the pro-forma schedule for each service and port rotation, count the share of calls that fall inside their own on-time tolerance, and average the delay on the calls that do not. Tolerance, coverage and trade lane weighting differ between providers, which is why the figure is meaningful as a trend inside a single series and across carriers inside the same report.

The Global Liner Performance report is published monthly and, at issue 181 covering the figures to August 2026, spans 34 trade lanes and 60 or more carriers. It reports a global figure, carrier level figures for the 13 largest lines, alliance figures, trade lane detail and port level data. Alliance figures carry two bases, all arrivals and trade arrivals, and the two are not always equal: in April and May 2026 Gemini Cooperation recorded 89.5% across all arrivals and 91.4% across trade arrivals, while MSC recorded 79.5% and 79.7% (Sea-Intelligence). Quoting the wrong column changes the comparison.

Where the global figure stands in 2026

Month (2026)Global schedule reliabilityAverage delay, late arrivals
January62.4%5.17 days
February59.0%5.49 days
March62.2%5.48 days
April62.4%5.34 days
May64.7%5.52 days
June62.6%5.31 days
July56.4%6.06 days
August49.9%6.81 days

Source: Sea-Intelligence Global Liner Performance monthly press releases, each published in the month after the data month (January, February, March, April, May, June, July, August). The August reading was the lowest since September 2022 and a fall of 5.9 percentage points in a single month, with the average late arrival at 6.81 days, the highest since March 2022. It was the second consecutive monthly decline, and no carrier improved month on month.

The pressure is concentrated in Asia. Sea-Intelligence put Asian vessel schedule reliability at 32.3% in August 2026 with average late arrival delays of 7.28 days, China at 23.9% and Shanghai and Ningbo at 12.2% and 16.9% (Sea-Intelligence). Our 4 October briefing covered that month in full.

What drives reliability down

Queueing is the mechanism, not a shortage of ships. When a vessel misses its berth window it leaves out of sequence, arrives late at the next port, and often starts its next voyage late as well. In July 2026 all 14 of Asia’s busiest ports recorded a fall in on-time arrivals: Shanghai dropped to 21.0%, which Sea-Intelligence describes as the lowest in 14 years of recorded data outside pandemic disruption, while Yantian fell to 48.3%, Singapore to 43.2%, Busan to 40.9% and Port Klang to 33.3% (Sea-Intelligence). Weather that arrives on top of an already tight port system, as repeated typhoons did through the 2026 Asian summer, compounds the effect across the whole network.

Carriers have two recovery tools, and both move cargo later. Blank sailings and port omissions let a vessel skip a call and catch up on schedule, at the cost of shifting cargo to a following sailing. Network design matters as well: service level analysis published in May 2026 found the global average masks a fractured market, with Asia and Mediterranean services showing 33% of services in the most stable tier by February 2026 while Asia and North Europe had 81% of services sitting in a middle band (Sea-Intelligence). A single global percentage cannot describe both.

Why it matters to a shipper

Average transit time is a planning input; reliability is a risk input, because late arrivals cascade into missed feeder connections, late container availability and charges. Demurrage and detention are the direct costs of a container that misses its free time window, and inland or transhipment connections are where the delay is usually absorbed.

The systemic cost is capacity. Sea-Intelligence calculated in August 2026 that 5.0% of all global deep-sea capacity was tied up by vessel delays, against an average of 2.2% between 2011 and 2019, equal to roughly 1.7m TEU of space that is not moving cargo, a fleet that would rank as the eighth largest container line, or 1.0m TEU more than the pre-pandemic baseline (Sea-Intelligence). That capacity effect is one of the channels through which reliability reaches price, alongside the spot and contract distinction that freight rate indexes measure.

How the number is commonly misread

  • The global average hides the lanes. An operator can be punctual on one trade and erratic on another. Read your lane, and your port rotation, not the headline.
  • Percentage and delay can move in opposite directions, as June 2026 showed. Always read the pair.
  • Carrier and alliance figures cover different populations. Carrier level scores sit alongside alliance scores built on all arrivals or trade arrivals, so compare like with like.
  • A high percentage still means a lot of late vessels. At 60% reliability on a service calling at several ports, a large share of individual calls still miss their window.
  • Reliability is not a guarantee. Even in a calm market, a vessel arrives late on a share of calls; plan for the distribution, not the best case.

What to watch

The first test is whether Asian congestion clears and the global figure recovers toward the 70 to 80% band that Sea-Intelligence describes as the 2011 to 2019 normality. The second is whether the delay absorption figure falls back toward 2.2%, which would release capacity without a single new ship. The third is service level stability rather than the average, because a lane can improve on paper while volatility rises underneath it.

Sources

Frequently asked questions

What counts as a good schedule reliability figure?
Sea-Intelligence describes 70 to 80% as the pre-pandemic normality of 2011 to 2019, when the industry treated it as a stable operating environment. The global figure was 49.9% in August 2026, the lowest since September 2022, so the market is currently far below that band.
Is schedule reliability the same as transit time?
No. Transit time is how long a container takes on the advertised routing. Schedule reliability is how often the vessel actually arrives on the day the operator published. A service can quote a competitive transit time and still deliver it late a third of the time, which is why reliability is a risk measure rather than a routing measure.
Which carriers were the most reliable in August 2026?
Sea-Intelligence put Maersk first among the 13 largest carriers at 67.3%, followed by Hapag-Lloyd at 61.5%, MSC at 55.2% and CMA CGM at 50.6%. Wan Hai was the least reliable at 23.2%, and no carrier improved month on month.
Why do two providers publish different reliability figures?
Providers set their own tolerance for what counts as on time and cover different sets of carriers, ports and trades, so their percentages are not directly comparable. Use one provider's series and follow it over time rather than comparing a figure from one firm against a figure from another.

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