Built for everyone who has to name a ship correctly: charterers and cargo owners deciding what tonnage fits their trade, brokers and operators talking daily in "Kamsarmax" and "Aframax," analysts sizing markets, and newcomers drowning in a soup of "-max" words. The size classes are scattered across class-society glossaries and half-remembered rules of thumb. We assembled the whole taxonomy — every class, its DWT range, what it carries and where it physically fits — into one reference.
The rynda voyage-economics calculator auto-classifies a vessel from its DWT and type, and the tonnage board lets you filter live positions by exactly these classes.
📖 See also: How to charter a ship · Freight rates & the market · ECA / SECA zones reference
Contents
- At a glance
- Two numbers that define a ship
- Dry bulk carriers
- Tankers (crude & product)
- Gas carriers (LPG, LNG)
- Container ships
- Specialised and other types
- Beyond size: age, eco and gear
- The "-max" families explained
- Where each class fits — canals and ports
- What each class typically carries
- Model it on rynda
- FAQ
- References
At a glance
The short version, if you read nothing else:
- Ships are classed by cargo type (bulk, tanker, gas, container, ro-ro…) and, within each, by size — measured in deadweight tonnes (DWT) for bulk/tankers and TEU (twenty-foot container-equivalent units) for boxships.
- The "-max" names are physical fit constraints, not marketing: Panamax fits the old Panama locks, Suezmax transits the Suez Canal laden, Newcastlemax is the biggest ship into the port of Newcastle, Seawaymax fits the St Lawrence Seaway.
- Dry bulk ladder: Handysize → Handymax/Supramax/Ultramax → Panamax/Kamsarmax → Post-Panamax → Capesize → Newcastlemax → VLOC.
- Tanker ladder: Coastal/Product (MR) → LR1 → Aframax/LR2 → Suezmax → VLCC → ULCC.
- What limits a ship is rarely the ocean — it's a canal, a port's draft, or a berth's length. The class name usually encodes which one.
- The DWT boundaries between classes are conventions, not law — sources differ by a few thousand tonnes at the edges. This reference gives the widely used ranges and flags where they wobble.
Two numbers that define a ship
Before the classes, two measurements you must not confuse:
- Deadweight tonnage (DWT) — the carrying capacity: the total weight (cargo + fuel + stores + crew + water) a ship can carry when loaded to her marks, in tonnes. This is the number the size classes are built on. A "180,000 DWT bulker" can carry ~180,000 t all-in.
- Gross tonnage (GT) — a volume measure of the whole enclosed ship (not weight), used for regulations, manning, port dues and safety rules (ECA/ETS thresholds are in GT). GT and DWT are different scales — never interchange them.
Two more you'll meet: NRT (net register tonnage, the earning volume, used for some canal/port dues) and LDT (light displacement tonnage, the empty steel weight, used in scrap sales). And the physics underneath: displacement is the actual weight of water the ship pushes aside — light displacement is the empty ship, loaded displacement is the ship at her marks, and DWT = loaded displacement − light displacement (i.e. everything you can add). That's why cargo classes are built on DWT, not displacement: DWT is the part you can sell. DWT sizes the cargo classes, and that's what the ladders below use.
Dry bulk carriers
Carriers of unpackaged bulk commodities (ore, coal, grain, bauxite, cement). The dominant ladder, with widely used DWT ranges:
| Class | DWT range | Notes |
|---|---|---|
| Coaster / Mini-bulker | < 10,000 | Short-sea, river-capable, small ports. |
| Handysize | ~10,000–40,000 | Geared (own cranes); reaches small/restricted ports. |
| Handymax / Supramax | ~40,000–60,000 | Geared; the minor-bulk workhorse. Supramax ≈ 50–60k. |
| Ultramax | ~60,000–65,000 | Modern, larger-geared evolution of Supramax. |
| Panamax | ~65,000–80,000 | Fits the old Panama locks (beam ≤ 32.31 m). Coal, grain. |
| Kamsarmax | ~80,000–85,000 | Max length to load at Port Kamsar (Guinea bauxite); a bigger Panamax. |
| Post-Panamax | ~85,000–120,000 | Too wide for the old locks; fits the new Neopanamax locks. |
| Capesize | ~120,000–200,000 | Too big for Panama/Suez laden — routes via the Capes. Iron ore, coal. |
| Newcastlemax | ~185,000–210,000 | The true limit is Newcastle's (Australia) beam ≤ 50 m, LOA ≤ 300 m, not a DWT floor. |
| VLOC / Valemax | ~200,000–400,000 | Very large ore carriers; Valemax ~400k for Brazil–China iron ore. |
The commercial heart of dry bulk is the Baltic-indexed quartet — Capesize, Panamax, Supramax, Handysize — whose time-charter rates make up the Baltic Dry Index.
Tankers (crude & product)
Carriers of liquid cargo. "Dirty" tankers move crude and fuel oil; "clean" tankers move refined products. The ladder:
| Class | DWT range | Notes |
|---|---|---|
| Coastal / Small tanker | < 15,000 | Short-sea product distribution. |
| MR (Medium Range) | ~25,000–55,000 | The clean-products workhorse (gasoline, diesel, jet). |
| LR1 (Long Range 1) | ~55,000–85,000 | Larger products, or crude; Panamax-beam. |
| Aframax / LR2 | ~80,000–120,000 | Crude (Aframax) or products (LR2). Named from the Average Freight Rate Assessment system. |
| Suezmax | ~120,000–200,000 | Sized around the Suez Canal (historical definition; the canal's current ~20.1 m draft limit now passes some larger vessels laden, and many VLCCs part-laden). ~1 m barrels of crude. |
| VLCC (Very Large Crude Carrier) | ~200,000–320,000 | The Middle East → Asia/Europe crude mainstay; ~2 m barrels. |
| ULCC (Ultra Large Crude Carrier) | ~320,000–550,000 | The giants; few remain, restricted to deepwater terminals. |
Tanker freight is usually quoted in Worldscale, not $/tonne — see the freight rates reference. The Baltic dirty/clean tanker indices (BDTI/BCTI) track these classes.
Gas carriers (LPG, LNG)
Pressurised/refrigerated carriers of liquefied gases — a distinct, capital-intensive segment, sized by cubic metres (m³) of tank capacity as much as DWT:
| Class | Capacity | Cargo |
|---|---|---|
| Small LPG / pressurised | < ~10,000 m³ | Regional LPG, petrochemicals. |
| MGC (Medium Gas Carrier) | ~15,000–40,000 m³ | LPG, ammonia, petrochemical gases. |
| LGC (Large Gas Carrier) | ~40,000–60,000 m³ | LPG. |
| VLGC (Very Large Gas Carrier) | ~60,000–90,000 m³ | The LPG mainstay (~84,000 m³ typical). |
| VLEC (Very Large Ethane Carrier) | ~85,000–100,000 m³ | Ethane for petrochemicals. |
| LNG carrier | ~120,000–180,000+ m³ | Liquefied natural gas at −162 °C; membrane or Moss-type tanks. |
LNG carriers are among the most expensive merchant ships built and are usually employed on long-term charters, not the spot market.
Container ships
Sized by TEU (twenty-foot equivalent units), not DWT:
| Class | Capacity (TEU) | Notes |
|---|---|---|
| Feeder / Feedermax | < ~3,000 | Short-sea, connect small ports to hubs. |
| Sub-Panamax | ~2,000–3,000 | Pre-Panamax-era sizing. |
| Panamax (box) | ~3,000–5,100 | Old-locks beam limit (~32.3 m). |
| Post-Panamax | ~5,100–10,000 | Too wide for old locks. |
| Neo-Panamax (New Panamax) | ~10,000–15,000 | Fits the new Panama locks (2016). |
| ULCV (Ultra Large Container Vessel) | > ~15,000 (up to ~24,000+) | The giants; Asia–Europe only, deepwater hub ports. |
Container liner trade is scheduled and operator-run, distinct from the tramp (per-fixture) world of bulk and tanker chartering.
Specialised and other types
Beyond the four main families:
| Type | Carries |
|---|---|
| Ro-Ro | Rolling cargo (trucks, trailers) driven on/off via ramps. |
| PCTC / PCC | Pure Car (and Truck) Carriers — vehicles on multiple decks. |
| ConRo | Combined container + ro-ro. |
| Reefer | Refrigerated perishables (now largely reefer-container trade). |
| Open-hatch bulker | Box-shaped holds for unitised forest products, project cargo. |
| MPP / general cargo | Multi-purpose; break-bulk and containers, often geared. |
| Heavy-lift / project | Oversized indivisible cargo (turbines, modules). |
| OBO / combination carrier | Ore/Bulk/Oil — switchable between dry and wet (rare today). |
Beyond size: age, eco and gear
Two ships of identical DWT can command very different hire — because a charterer is also buying fuel efficiency and self-sufficiency:
- Eco vs conventional. Post-2013 "eco" designs (and, separately, scrubber-fitted ships) burn materially less fuel per day. In a firm bunker market that saves thousands of dollars a day, so an eco ship earns a hire premium over an older conventional sister of the same size. This is why age and design come up in every time-charter negotiation.
- Geared vs gearless. A geared ship carries its own cranes and can work cargo at ports with no shore equipment — the reason Handysize/Supramax are almost always geared. Gearless ships (most Panamax and virtually all Capesize) are cheaper to build and slightly more efficient but depend on the terminal's gear, so they're restricted to well-equipped ore/coal/grain berths. Gear decides which ports and cargoes a ship can serve as much as size does.
The "-max" families explained
The "-max" suffix always means "the maximum that fits [some constraint]." Knowing the constraint tells you the real limit:
| Name | Constraint | Governing dimension |
|---|---|---|
| Panamax | Old Panama Canal locks | Beam ≤ 32.31 m, LOA ≤ 294 m |
| Neopanamax | New Panama locks (2016) | Beam ≤ 51.25 m, LOA ≤ 366 m |
| Suezmax | Suez Canal, laden | Draft/beam envelope (~20.1 m draft at ≤ 50 m beam) |
| Kamsarmax | Port Kamsar (Guinea) berth | LOA ≤ ~229 m |
| Newcastlemax | Port of Newcastle (Australia) | LOA ≤ ~300 m, beam ≤ ~50 m |
| Malaccamax | Strait of Malacca controlling depth (~25 m water) | Laden draft ~20 m (the ship; ~25 m is the channel, not the hull) |
| Seawaymax | St Lawrence Seaway locks | LOA ≤ 226 m, beam ≤ 24 m |
| Aframax | (Not a canal) Average Freight Rate Assessment tier | Historical rate-band, ~80–120k DWT |
So a "Newcastlemax" isn't a random size — it's the biggest bulker the Newcastle coal port can take. The name is a spec sheet.
Where each class fits — canals and ports
The practical reason classes exist: transit and terminal limits. A rough fit map (2026 canal limits):
| Route constraint | Fits up to | Excludes |
|---|---|---|
| Old Panama locks | Panamax (beam ≤ 32.31 m) | Post-Panamax and larger |
| New Panama (Neopanamax) locks | Neopanamax (beam ≤ 51.25 m, draft ≤ ~15.2 m TFW) | ULCC, ULCV, Valemax |
| Suez Canal (laden) | Suezmax; VLCCs often transit part-laden or in ballast | Fully laden ULCC |
| St Lawrence Seaway | Seawaymax (LOA ≤ 226 m) | Panamax and larger |
| Strait of Malacca | Malaccamax (~20 m laden draft; ~25 m channel depth) | The very deepest-draft giants |
Capesize and larger are named for what they can't do: transit Panama/Suez laden, so they route via the Cape of Good Hope or Cape Horn. For the exact canal beam/draft/air-draft numbers, pair this with a voyage routing that respects them — the voyage-economics calculator applies canal transit costs and restrictions by class.
What each class typically carries
Matching cargo to class is the charterer's first decision:
| Cargo | Typical class |
|---|---|
| Iron ore (long haul, Brazil/Australia → China) | Capesize, Newcastlemax, VLOC/Valemax |
| Coal (thermal/coking) | Capesize, Panamax |
| Grain (US Gulf, Black Sea, S. America) | Panamax, Supramax, Handysize |
| Bauxite / alumina | Kamsarmax, Panamax |
| Minor bulks (steels, fertilisers, cement, salt) | Supramax, Handysize (geared) |
| Crude oil (Middle East → Asia) | VLCC, Suezmax |
| Crude / fuel oil (regional) | Aframax, Suezmax |
| Refined products (gasoline, diesel, jet) | MR, LR1, LR2 |
| LPG / ammonia | VLGC, MGC |
| LNG | LNG carrier |
| Containers | Feeder → ULCV by trade lane |
| Vehicles | PCTC / PCC |
The pairing runs both ways: a cargo owner picks a class for their parcel size and port depth; an owner positions a class where its cargoes are. The cargo and tonnage boards are where those two searches meet.
Model it on rynda
- Auto-classification: the voyage-economics calculator classifies a ship from DWT + type into these classes and applies the right speed/consumption and canal profile.
- Filter live tonnage by class: the tonnage/vessels board and fleet map let you find and track ships by exactly these categories.
- Match cargo to ship: post a parcel on the cargo board or a position on the tonnage board and let the class do the filtering.
FAQ and common confusions
Q: DWT or GT — which is the "size"?
A: DWT (deadweight, a weight/carrying capacity) defines the cargo size classes. GT (gross tonnage, a volume) drives regulations and dues. They're different scales — a ship has both, and they're not convertible.
Q: Why is it called "Panamax" if it can't fit the new locks?
A: "Panamax" predates the 2016 expansion and means the old locks (beam ≤ 32.31 m). Ships built for the new locks are Neopanamax. Both names persist.
Q: Aframax — what's the "A" for?
A: Average Freight Rate Assessment, a 1950s tanker rate-band system. It's a rate tier that became a size name (~80–120k DWT), not a canal limit.
Q: What's the difference between Supramax, Ultramax and Handymax?
A: All geared bulkers around 40–65k DWT. Handymax ≈ 40–50k, Supramax ≈ 50–60k, Ultramax ≈ 60–65k — successive, slightly larger generations.
Q: Why can't a Capesize use the Suez or Panama Canal?
A: Laden, it's too big for both. Capesize and up route around the Cape of Good Hope or Cape Horn — hence the name.
Q: How are container ships sized if not by DWT?
A: By TEU (twenty-foot equivalent units) — how many standard boxes they carry. A ULCV exceeds ~15,000 TEU; a feeder is under ~3,000.
Q: Are these DWT boundaries official?
A: No — they're market conventions and differ by a few thousand tonnes between sources. Use them as ranges, not hard lines; the class name plus the physical limit (canal/port) is what actually matters.
Q: What's a Valemax?
A: A ~400,000 DWT VLOC (very large ore carrier) built for Vale's Brazil→China iron-ore trade — among the largest bulk carriers afloat, restricted to deepwater ore terminals.
References
- Clarksons — A Guide to Bulk Vessel Sizes; vessel-size glossary.
- Baltic Exchange — Guide to Modern Shipping: Main Vessel Types; the indexed size classes.
- Panama Canal Authority (ACP) and Suez Canal Authority (SCA) — official vessel-dimension limits (2026).
- Class societies (DNV, Lloyd's Register, ABS) — tonnage definitions (DWT/GT/NRT/LDT).
- rynda voyage-economics calculator and tonnage board.
Document version
- 2026-07 — first public version. Bulk, tanker, gas, container and specialised classes with DWT/TEU ranges, the "-max" constraints, and canal/port fit. DWT boundaries are market conventions and vary by source.