Internal dimensions, payload limits, door opening, and typical use for the eight most-booked sea-freight container types out of China. Built on ISO 668:2020 nominal values; the actual data-plate tare on the container booked for your shipment is the authoritative number for VGM submission under SOLAS.
Eight common types, with the values you actually quote: internal dimensions, usable volume, max gross, tare, payload, door opening, and typical cargo. Use the tare from the data plate on the booked container for VGM under SOLAS, not the nominal in the table.
20GP
| Internal length | 5.898 m |
| Internal width | 2.352 m |
| Internal height | 2.393 m |
| Internal volume | 33.2 m³ |
| Max gross mass | 30,480 kg |
| Tare (nominal) | 2,300 kg |
| Door opening (W × H) | 2.343 × 2.276 m |
Workhorse for dense chemical cargo. Drums, IBCs, palletised bags. Weights-out before it cubes-out for most chemical product.
40GP
| Internal length | 12.032 m |
| Internal width | 2.352 m |
| Internal height | 2.393 m |
| Internal volume | 67.7 m³ |
| Max gross mass | 32,500 kg |
| Tare (nominal) | 3,900 kg |
| Door opening (W × H) | 2.343 × 2.276 m |
Same width and height as 20GP, double the length. Same payload limit, almost. Picks up the volume but not the mass.
40HC
| Internal length | 12.032 m |
| Internal width | 2.352 m |
| Internal height | 2.698 m |
| Internal volume | 76.4 m³ |
| Max gross mass | 32,500 kg |
| Tare (nominal) | 4,000 kg |
| Door opening (W × H) | 2.343 × 2.585 m |
30 cm taller than 40GP. Adds about 11 m³ for low-density cargo. Watch destination dock-door height; some old US loading docks max out at 2.59 m.
20RF
| Internal length | 5.450 m |
| Internal width | 2.290 m |
| Internal height | 2.270 m |
| Internal volume | 28.3 m³ |
| Max gross mass | 30,480 kg |
| Tare (nominal) | 3,050 kg |
| Door opening (W × H) | 2.290 × 2.230 m |
Refrigerated, set point typically minus 30 to plus 30 degrees Celsius. Insulation and refrigeration unit eat about 5 m³ from the equivalent dry container. Used for temperature-sensitive chemicals and for produce.
40RH
| Internal length | 11.580 m |
| Internal width | 2.290 m |
| Internal height | 2.550 m |
| Internal volume | 67.6 m³ |
| Max gross mass | 32,500 kg |
| Tare (nominal) | 4,350 kg |
| Door opening (W × H) | 2.290 × 2.500 m |
Refrigerated 40HC. Smaller internal volume than 40HC dry; reefer machinery and insulation steal the difference. Common for fine chemicals shipped at controlled temperatures.
20OT
| Internal length | 5.898 m |
| Internal width | 2.352 m |
| Internal height | 2.350 m |
| Internal volume | 32.6 m³ |
| Max gross mass | 30,480 kg |
| Tare (nominal) | 2,400 kg |
| Door opening (W × H) | 2.343 × 2.286 m (plus open roof) |
Top loads through a removable tarpaulin and roof bows. For cargo that does not fit through the door, machinery stuffed top-down, or pallets that exceed door height. Surcharge applies; OOG (out-of-gauge) bookings have to be cleared with the carrier.
20FR
| Internal length | 6.058 m |
| Internal width | 2.438 m |
| Internal height | 2.327 m |
| Internal volume | n/a |
| Max gross mass | 34,000 kg |
| Tare (nominal) | 2,750 kg |
| Door opening (W × H) | open sides, collapsible end-walls |
No walls, no roof, end-walls collapse. For machinery, pipes, vehicles, or oversized chemical equipment. Lashing and bracing become the operator job; OOG ratings apply.
20TK
| Internal length | 6.058 m |
| Internal width | 2.438 m |
| Internal height | 2.591 m |
| Internal volume | 24,000 L nominal |
| Max gross mass | 36,000 kg |
| Tare (nominal) | 4,000 kg |
| Door opening (W × H) | top and bottom valves only |
IMO Type 1 portable tank for bulk liquid. The container IS the packaging. T11 is the most common for non-pressurised liquids; T14 for higher-pressure or corrosive cargo. See /tools/iso-tank-loading for fill math under IMDG 4.2.1.9.
Container choice is rarely a free decision. The 40HC costs the same ocean-freight rate as a 40GP on most lanes (carriers price by 20 ft or 40 ft slot, not by box height), so a high cube is a free 11 m³ for low-density cargo. For dense chemicals where the box weights-out at 28 tonnes, the extra height does nothing useful and the 40GP is the right book. A 20GP at 28 tonnes payload and a 40GP at 28 tonnes payload carry the same mass at meaningfully different freight rates per kilogram, because the 40 ft slot is roughly 1.4 to 1.7 times the 20 ft slot rate, not 2 times.
The reefer adds capital cost (the refrigeration unit and the genset on rail moves) and a per-kilometre energy cost. The carrier passes both to the shipper as a reefer surcharge plus the higher base rate. Reefers are mandatory for cargo with a temperature range that survives Suez to East Coast (the 21 to 35 day Asia to US East Coast window can hit 35 degrees in the Red Sea); they are the wrong book for stable dry chemical cargo where the surcharge buys nothing.
Open-top and flat-rack are out-of-gauge bookings whether the cargo physically clears the dimensions or not. The booking ties up extra carrier resource (lashing and bracing inspection, extra freight forwarder paperwork, possible advance approval from the master) and the rate reflects that. Use them when you have to; do not use them as a clever workaround when a 40HC would do.
An ISO tank rents from the operator (Stolt, Hoyer, Bulkhaul, Newport) under a typical 30-day rental window, not from the carrier. The cost is the rental plus the freight of a 20 ft slot. For chemical cargo above about 20 tonnes per shipment, the tank often beats drums on landed cost because there is no drum inventory, no drum disposal at destination, and no internal-packaging dunnage; the cargo flows directly between the tank and your destination storage tank.
The booking. A US buyer asks for 12 metric tonnes of sodium hydroxide 50 percent solution in 200 L drums. Each drum holds 252 kg of caustic at 1.26 specific gravity, plus 22 kg drum tare, totalling 274 kg per filled drum. Twelve tonnes net is 47.6 drums, round up to 48 drums. The freight forwarder offers a 20GP at 2,400 USD all-in or a 40HC at 3,800 USD all-in to LA, including THC and BL. Buyer thinks the 40HC is the answer because it has more volume.
The failure. The 20GP at 28,180 kg payload comfortably carries 48 drums at 274 kg each (13,152 kg cargo plus 22 kg drum tare per drum, total 13,152 kg, well below the 28,180 kg cap). Forty-eight drums at 0.59 m diameter and 0.88 m height, single-tier, fit in a 20GP at about 80 drums maximum (cylinder pack at 0.75 efficiency). The 40HC at 28,500 kg payload would carry the same cargo with three-quarters of the box empty, paid for at 1,400 USD more freight. Either book the 20GP and pay 2,400 USD, or book the 40HC and waste 1,400 USD on empty space.
The fix. Book the 20GP. The freight invoice lands at 2,400 USD. The buyer pays 50 USD per drum for ocean freight (2,400 / 48), versus 79 USD per drum on the 40HC. Container weights-out is rarely a 12-tonne problem; container cubes-out is rarely a 12-tonne problem either. The right container is the smaller container that holds the cargo. The 40HC is the answer when the cargo is 24 tonnes, not 12 tonnes.
Same length (12.032 m internal) and same width (2.352 m). The 40HC is 30 cm taller (2.698 m versus 2.393 m), giving about 11 m³ more cargo volume. Same maximum gross mass and almost the same payload, since the HC tare is only about 100 kg heavier. The HC is the right pick for low-density cargo where you cube-out before you weight-out, and a poor pick for dense chemicals where weight-out hits long before you fill the box.
The reefer carries an insulation lining and a refrigeration unit on the front wall. Both add tare mass. 20RF tare is around 3,050 kg versus 2,300 kg for the 20GP dry, so the payload available for cargo drops to about 27,430 kg. The internal volume also drops (28.3 m³ versus 33.2 m³) because the insulation lining steals about 5 m³ of cargo space.
When the cargo will not fit through the standard door (door height 2.276 m on a 20GP), or when the cargo has to be loaded by overhead crane rather than through the doors. Common uses: machinery, pipes, oversize chemical equipment. The carrier surcharges open-tops and may classify the booking as OOG (out-of-gauge), which requires advance approval.
A flat rack has no roof and no side walls; only the floor and (for some types) collapsible end-walls. It is for cargo that exceeds container width or that needs side-loading by crane. An open top has full side walls but a removable roof, for top-loading cargo that fits the floor footprint but not the door. Both attract OOG handling and additional carrier paperwork.
The carrier prints the tare on the data plate next to the container doors and on the bill-of-lading-equipment record. Standard tare values (in this reference) are nominal manufacturer values; actual containers vary by 50 to 200 kg depending on age and any repair-and-replate work the box has had. For VGM (verified gross mass) submission under SOLAS, use the tare on the data plate, not the nominal.
The tank is the packaging. Bulk liquid is loaded through a top manhole or a top valve and discharged through a bottom valve. There is no door because there is no internal cargo space to enter. Tank designations (T11, T14, T50, T75) reflect the design pressure, the pressure-relief specification, and the cargo class the tank is approved for under the IMDG Code. See /tools/iso-tank-loading for the fill math against IMDG 4.2.1.9.
Compute how many drums, IBCs, big bags, or paper-bag pallets fit a 20GP, 40GP, 40HC, or reefer container, weight-out vs cube-out.
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Maximum loadable volume and mass for any ISO tank build (T1 through T22 plus T23, T50, T75) under the IMDG 4.2.1.9 fill rules.
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EFTCO cleaning code letters A-J decoded with typical USD ranges, plus compatibility table for 8 common chemical-trade transitions (NaOH to H2SO4, methanol to ethanol, FAME to diesel, phenol cleanup, food-grade after industrial).
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