Shipping Container Dimensions: 20ft, 40ft, 40HC, 45HC, Reefer, Open Top

A container carries three separate dimension sets: nominal (the "20ft/40ft" label), external (fixed by standard), and internal. Only the internal set describes the space cargo actually occupies, and it is the set tabulated below. Every figure on this page is an internal or door measurement unless stated otherwise; the full sortable spec sheet lives on the container specifications page.

The listed values are representative and fall within ISO 668 tolerances — an individual unit varies by a few centimeters with manufacturer and build year. For any single piece within roughly 5 cm of a listed limit, confirm the specific unit's dimensions with the carrier before committing.

Internal Dimensions by Container Type

What ISO 668 Fixes and What It Does Not

The external column is the one the standard nails down. ISO 668 sets a 40ft unit at 12.192 m long and 2.438 m wide everywhere on earth, with an external height of 2.591 m for standard units and 2.896 m for high cubes. That fixed envelope is the point of containerization: every ship cell guide, chassis twist-lock, and crane spreader of the last five decades engages the same corner castings. The internal column is what the standard leaves open — internal dimensions are the remainder after walls, corrugation, flooring, and door hardware, and that remainder drifts slightly by manufacturer and build series. That is precisely why the table above is representative rather than contractual.

For weight, two markings on the unit override any table. The CSC safety approval plate (under the International Convention for Safe Containers) states the unit's maximum gross weight, and the tare weight stamped on the door is the figure a Verified Gross Mass declaration must use — repairs and re-flooring shift tare across a container's life, so the stamp beats the tabulated average. The interaction of tare, payload, and VGM is set out in container weight limits and VGM.

Reading Each Column

Door W × H is the binding constraint, not Internal W × H. The aperture (234 × 228 cm on standard dry units) is smaller than the internal cross-section, so a machine 235 cm wide fits inside a container it cannot pass through the door of. Over-door pieces move on Open Tops (loaded from above by crane) or Flat Racks.

High Cube changes the height figure only. The 40HC's extra 30 cm adds 8.6 m³ (+13%) over the 40DC at nearly identical tare. For light, voluminous cargo that is usually the best value on the market; for dense cargo that reaches the payload limit first it adds nothing — note the 40HC's max payload is in fact a touch lower than the 40DC's.

Max payload is a structural ceiling, not a loading target. Road legs usually bind tighter: US highway rules effectively cap a 40ft's cargo around 19–20 t and a 20ft's around 17–19 t on standard chassis. Booking 28 t into a 40DC is legal on the water and illegal on the truck. Details in container weight limits and VGM.

The reefer row is not a dry row minus a little. Insulation and the refrigeration unit cost the 20ft reefer about 47 cm of length, 7 cm of width, and 13 cm of height against a 20DC, and cargo must stay below the red load line for air circulation. Reefer loads are planned on the reefer figures, never on dry-container dimensions.

The High Cube's 30 cm, Quantified

The elevation resolves the height row into layer counts. Stacked upright, a common 60 × 40 × 40 cm export carton fills five layers in a standard 40ft (200 cm used, 39 cm of dead headroom) and six in the 40HC. Extended across the whole floor, the best pattern reaches roughly 550 cartons in a 40DC versus 650 in a 40HC — an 18% gain from a box of the same footprint, similar tare, and typically a modest rate premium. Reproduce it: the carton in a 40HC against the same carton in a 40DC, or total the shipment first in the CBM calculator.

The gain is carton-dependent, not automatic. A 55 cm-tall carton stacks four layers in both boxes — 270 ÷ 55 still rounds down to four — so the added height returns nothing until it completes a layer. That remainder arithmetic is what a packing simulation captures and a volume division misses; more of it in how many CBM really fit per container.

Where Dimension Numbers Get Misread

• Planning to the nominal or external number. A "40ft" container is 12.19 m outside but 12.035 m inside. Crates cut to the external figure will not load, and the discovery typically lands at the warehouse door with the truck waiting — re-crating plus a missed vessel cut-off converts a measuring slip into a week or more of delay.

• Reading the ceiling and ignoring the aperture. A machine 232 cm tall clears the 239 cm interior but not the 228 cm door. The fallback is Open Top or Flat Rack equipment, quoted case-by-case and routinely a large multiple of a dry-box rate.

• Applying dry figures to a reefer. A 20ft reefer holds 28.0 m³ against a 20DC's 33.2. Plan on the dry number and roughly 15% of the order stays on the dock — split shipment, unhappy consignee, a second set of fees.

• Loading to the payload plate. 28 t in a 40DC is fine at sea and overweight on a standard US chassis — an overweight citation, part of the cargo trans-loaded to a second truck, and the same mile paid for twice.

• Trusting the table for a tight fit. For pieces within roughly 5 cm of an internal limit, request the specific unit's dimensions or a survey. Internal tolerances are small, but so is the margin.

Selecting Equipment by Constraint

• By volume: up to ~26 CBM of cartons → 20DC; up to ~56 → 40DC; up to ~66 → 40HC (see practical capacity for why these sit below nominal).

• By weight: dense cargo past ~19 t often ships better as two 20DCs than one 40DC — axle limits split more comfortably.

• By piece size: anything exceeding the 234 × 228 cm door goes Open Top or Flat Rack, quoted case-by-case.

• By shipment size: below roughly 13–15 CBM, shared LCL space usually beats even a 20DC — the trade-offs are in FCL vs LCL.

To test a specific carton against a specific container — including orientation optimization and the weight-versus-volume bottleneck — use the container loading calculator.