If you've ever wondered how a container of goods reliably makes its way from a factory in one country to a warehouse in another often on a schedule known weeks or months in advance the answer lies in a system called mainline shipping.
What Is Mainline Shipping?
Mainline shipping, also known as Shipping Line or Liner service, is the backbone of global container trade. Unlike tramp shipping where vessels are chartered on an ad-hoc basis to carry whatever cargo is available, wherever it needs to go mainline shipping operates on fixed routes and fixed schedules.
Vessels transporting containers between ports follow a predetermined timetable that is published before departure. This means exporters, importers, and freight intermediaries can find out in advance:
- Future sailing schedules
- Voyage numbers
- Port calls (which ports the vessel will stop at)
- ETA (Estimated Time of Arrival)
- ETD (Estimated Time of Departure)
This information is available directly from the shipping line's office, and it's what allows businesses to plan the movement of goods strategically, well ahead of the actual shipment date.
The Two Pillars of Mainline Shipping
1. Fixed Route
A vessel's fixed route is made up of designated ports of call locations where the ship stops during its voyage specifically to load and discharge cargo. Rather than sailing wherever cargo happens to be waiting, the vessel follows the same loop of ports, voyage after voyage.
In industry terms, this loop of ports is often called a string, and each string typically serves a specific trade lane for example, an Asia–Europe string or a Trans-Pacific string.
2. Fixed Schedule
The fixed schedule is the predetermined timing behind that route the ETA and ETD at each port of call. Because this schedule is published in advance, it becomes a planning tool. A manufacturer can time production to meet a cut-off date; a buyer can plan inventory around a known transit time; a freight forwarder can commit to a delivery date with some confidence.
A few related terms that come up alongside ETA/ETD:
- Port rotation – the sequence of ports a vessel calls at during a voyage
- Transit time – the total time cargo takes from the origin port to the destination port
- Frequency – how often a sailing occurs on a given string (weekly, for instance)
- Cut-off – the deadline by which cargo and documentation must be submitted ahead of a sailing
Why This Matters for Exporters and Importers
The predictability of mainline shipping is really the whole value proposition. Because schedules are fixed and published, businesses across the supply chain can:
- Plan shipments and bookings weeks or months in advance
- Coordinate production and inventory around known transit times
- Set realistic delivery commitments to customers
- Compare transit times and frequencies across carriers before choosing a service
Major Mainline Shipping Companies
The mainline shipping industry is dominated by a handful of large global carriers, including:
- MSC (Mediterranean Shipping Company)
- Maersk
- CMA CGM Group
- COSCO Group
- Hapag-Lloyd
- ONE (Ocean Network Express)
- Evergreen Line
- HMM Co Ltd
- Yang Ming Marine Transport Corp
- Zim
It's worth noting that many of these carriers operate within shipping alliances, pooling vessel capacity across member lines to offer more frequent sailings and wider port coverage on shared strings. Alliance memberships shift periodically as market conditions change, so it's worth checking current alliance structures if that detail matters for your planning.
Top 30 Mainline Shipping Companies (Ranked by Fleet Capacity)
The table below ranks the world's 30 largest container shipping companies by total TEU (Twenty-foot Equivalent Unit) capacity, based on Alphaliner data. Capacity figures shift month to month as carriers take delivery of new vessels or retire older ones, but the relative rankings stay fairly stable over time.
| Rank | Company | Headquarters | Total TEU | Ships | Market Share | Alliance |
|---|---|---|---|---|---|---|
| 1 | MSC (Mediterranean Shipping Company) | Switzerland | 7,318,632 | 1,000 | 21.6% | Independent |
| 2 | Maersk | Denmark | 4,647,588 | 735 | 13.7% | Gemini Cooperation |
| 3 | CMA CGM | France | 4,273,202 | 723 | 12.6% | Ocean Alliance |
| 4 | COSCO Shipping Lines | China | 3,593,746 | 554 | 10.6% | Ocean Alliance |
| 5 | Hapag-Lloyd | Germany | 2,400,946 | 291 | 7.1% | Gemini Cooperation |
| 6 | ONE (Ocean Network Express) | Japan | 2,134,872 | 272 | 6.3% | Premier Alliance |
| 7 | Evergreen Marine Corporation | Taiwan | 1,973,231 | 239 | 5.8% | Ocean Alliance |
| 8 | HMM Co. Ltd. | South Korea | 1,029,773 | 97 | 3.0% | Premier Alliance |
| 9 | Yang Ming Marine Transport Corp. | Taiwan | 741,908 | 98 | 2.2% | Premier Alliance |
| 10 | ZIM Integrated Shipping Services | Israel | 698,205 | 115 | 2.1% | Independent |
| 11 | Wan Hai Lines | Taiwan | 591,132 | 120 | 1.7% | — |
| 12 | Pacific International Lines (PIL) | Singapore | 442,216 | 99 | 1.3% | — |
| 13 | X-Press Feeders | Singapore | 192,780 | 103 | 0.6% | — |
| 14 | SITC (Shandong International Transportation Corp.) | China | 187,472 | 121 | 0.6% | — |
| 15 | Unifeeder | Denmark | 165,289 | 94 | 0.5% | — |
| 16 | KMTC (Korea Marine Transport Corp.) | South Korea | 155,914 | 65 | 0.5% | — |
| 17 | IRISL Group | Iran | 142,180 | 29 | 0.4% | — |
| 18 | Global Feeder Shipping LLC | United Arab Emirates | 131,734 | 53 | 0.4% | — |
| 19 | Sinokor Merchant Marine | South Korea | 120,081 | 68 | 0.4% | — |
| 20 | TS Lines | Taiwan | 106,751 | 40 | 0.3% | — |
| 21 | Regional Container Lines (RCL) | Thailand | 101,908 | 33 | 0.3% | — |
| 22 | Emirates Shipping Line | United Arab Emirates | 98,114 | 22 | 0.3% | — |
| 23 | Ningbo Ocean Shipping Co. | China | 89,801 | 90 | 0.3% | — |
| 24 | Tangshan Port Hede Shipping | China | 85,867 | 57 | 0.3% | — |
| 25 | Interasia Lines | Japan | 77,985 | 27 | 0.2% | — |
| 26 | Grimaldi Group | Italy | 77,276 | 50 | 0.2% | — |
| 27 | Antong Holdings (QASC) | China | 73,446 | 72 | 0.2% | — |
| 28 | Sinotrans | China | 71,142 | 44 | 0.2% | — |
| 29 | SM Line | South Korea | 69,951 | 15 | 0.2% | — |
| 30 | Matson | United States | 69,227 | 28 | 0.2% | — |
Source: Alphaliner Top 100 (via Wikipedia's "List of largest container shipping companies"), data as of April 2026. Figures are approximate and shift monthly as fleets change; consult Alphaliner's live platform for current numbers.
A few observations from this table:
- Extreme concentration at the top: the top 4 carriers (MSC, Maersk, CMA CGM, COSCO) alone control nearly 60% of global container capacity, and the top 10 together account for roughly 85%.
- MSC's scale: MSC is the only carrier operating outside a formal alliance while still holding the largest capacity in the industry by a wide margin it became the first carrier to operate a fleet of 1,000 vessels.
- Alliance structure: the three major alliances as of 2026 are Gemini Cooperation (Maersk, Hapag-Lloyd), Ocean Alliance (CMA CGM, COSCO, Evergreen, OOCL), and Premier Alliance (ONE, HMM, Yang Ming) while MSC and ZIM operate independently of these groupings.
- Regional and niche carriers: ranks 11–30 are dominated by regional and feeder operators (serving intra-Asia, Middle East, and short-sea routes) rather than global deep-sea networks.
Because these figures move month to month with new vessel deliveries and charter changes, treat this table as a snapshot rather than a fixed reference it's worth checking a live source like Alphaliner's Top 100 for exact, up-to-date figures if you need them for a tender or contract.
Key Takeaways
- Mainline shipping runs on fixed routes and fixed schedules, unlike tramp shipping's ad-hoc model.
- A fixed route consists of designated ports of call, often grouped into a "string."
- A fixed schedule is defined by published ETAs and ETDs, letting shippers plan far in advance.
- Predictability is the core benefit: it enables strategic planning of production, inventory, and delivery timelines.
- Major global carriers MSC, Maersk, CMA CGM, COSCO, Hapag-Lloyd, ONE, Evergreen, HMM, Yang Ming, and ZIM dominate the mainline shipping market, often coordinating through alliances.
- Among the top 30 carriers by fleet capacity, the top 10 alone control roughly 85% of global TEU capacity, with MSC leading as an independent operator ahead of alliance-based rivals.
Frequently Asked Questions
Q1: What's the difference between mainline shipping and tramp shipping?
Mainline shipping follows fixed routes and published schedules, calling at the same ports on a repeating basis. Tramp shipping, by contrast, has no fixed route or timetable vessels are chartered to go wherever cargo demand takes them.
Q2: Where can I find a shipping line's sailing schedule?
Sailing schedules including voyage numbers, port calls, ETAs, and ETDs are published by the shipping line and can be obtained directly from the shipping office or the carrier's own booking platforms.
Q3: What does "port of call" mean?
A port of call is a designated port where a vessel stops during its voyage specifically to load or discharge cargo, as part of its fixed route.
Q4: Why does a fixed schedule matter to importers and exporters?
Because the schedule is known in advance, businesses can plan the movement of goods strategically coordinating production, inventory, and delivery commitments around a reliable transit time, rather than reacting to shipping availability at the last minute.
Q5: What is a shipping alliance?
A shipping alliance is an arrangement between multiple carriers to share vessel capacity on the same routes, allowing member lines to offer more frequent sailings and broader port coverage than they could individually.
Q6: Are all major carriers part of an alliance?
Most of the largest global carriers participate in one alliance or another, though membership and alliance structures can change over time as market conditions shift. It's best to verify current alliance line-ups if this detail is relevant to a specific shipment or contract.
Q7: How concentrated is the mainline shipping market?
Highly concentrated. The top 10 carriers by fleet capacity control roughly 85% of the world's total container shipping capacity, and the top 4 alone (MSC, Maersk, CMA CGM, COSCO) account for close to 60%. The remaining carriers in the top 30 and the many smaller operators beyond it are mostly regional or feeder lines serving specific trade lanes rather than global networks.