Shipping Container Dimensions & Specifications
The exterior dimensions of ISO Shipping Containers are 8'0" (2.438m) wide, and 8'6" (2.591m) tall. The most common lengths are 20' (6.058m) and 40' (12.192m). There are also "High Cube" containers, which are most common in 40' lengths, and are a foot taller at 9'6" (2.896m) tall.
Shipping container dimensions are held to very specific standards. The International Standard for Organization (ISO) requires that all containers are built to within a few millimeters of one another so they can be stacked on container ships without issue.
Containers are normally quantified in terms of twenty-foot equivalent units (TEU's) and are most commonly built in 20' and 40' lengths. Standard containers have an outside height of 8'6" tall, and "High Cube" containers have an outside height of 9'6".
Shipping Container Dimensions:

Ocean cargo containers are held to a rigid standard to ensure that there are no issues during shipping. Each intermodal shipping container (sometimes called "conex" containers) must be able to not only stack perfectly on a cargo ship, but also lock into chassis trailers safely and securely stack on rail cars. The International Organization for Standardization (ISO) sets the standards for shipping container dimensions (via ISO 668).
PLEASE NOTE: Dimensions may vary slightly, based on manufacturer. But these numbers should be very close.

20' Standard Shipping Container
External Dimensions
Length: 19' 10.50" - Width: 8' 0.00" - Height: 8' 6.00"
Internal Dimensions
Length: 18' 8.81" - Width: 7' 8.59" - Height: 7' 9.89"
Door Opening Dimensions
Width: 7' 8.125" - Height: 7' 5.75"
Capacity & Weight
Cubic Volume: 1,169 cubic feet - Empty Weight: 4,850 lbs - Load Capacity: 61,289 lbs

40' Standard Shipping Container
External Dimensions
Length: 40' 0.00" - Width: 8' 0.00" - Height: 8' 6.00"
Internal Dimensions
Length: 39' 5.70" - Width: 7' 8.59" - Height: 7' 9.89"
Door Opening Dimensions
Width: 7' 8.125" - Height: 7' 5.75"
Capacity & Weight
Cubic Volume: 2,385 cubic feet - Empty Weight: 8,380 lbs - Load Capacity: 57,759 lbs

40' High Cube Shipping Container
External Dimensions
Length: 40' 0.00" - Width: 8' 0.00" - Height: 9' 6.00"
Internal Dimensions
Length: 39' 4.00" - Width: 7' 7.00" - Height: 8' 9.00"
Door Opening Dimensions
Width: 7' 6.00" - Height: 8' 5.00"
Capacity & Weight
Cubic Volume: 2,660 cubic feet - Empty Weight: 8,598 lbs - Load Capacity: 58,598 lbs

45' High Cube Shipping Container
External Dimensions
Length: 45' 0.00" - Width: 8' 0.00" - Height: 9' 6.00"
Internal Dimensions
Length: 44' 4.00" - Width: 7' 7.00" - Height: 8' 9.00"
Door Opening Dimensions
Width: 7' 6.00" - Height: 8' 5.00"
Capacity & Weight
Cubic Volume: 3,040 cubic feet - Empty Weight: 10,580 lbs - Load Capacity: 55,559 lbs

10' Standard Shipping Container
External Dimensions
Length: 9' 10.50" - Width: 8' 0.00" - Height: 8' 6.00"
Internal Dimensions
Length: 8' 8.81" - Width: 7' 8.59" - Height: 7' 9.89"
Door Opening Dimensions
Width: 7' 8.125" - Height: 7' 5.75"
Capacity & Weight
Cubic Volume: 536.3 cubic feet - Empty Weight: 2,870 lbs - Load Capacity: 24,910 lbs

A Brief History of the Shipping Container
Early 20th Century Shipping
Prior to the 1950's, loading a cargo ship was a laborious process where cargo was loaded piece by piece onto a ship. During the Korean War, the US military developed the "Container Express" box system to make transporting supplies simpler. The term "Conex" comes from that system, and Conex is still synonymous with shipping containers to this day. There were also a large variety of different container systems in use prior to the 1950's, but each shipping container was still very different from company to company, and not easily interchangeable.
Containerization of Shipping
Malcom McLean is often credited with "inventing" the shipping container, but that's a bit of a stretch. McLean was certainly the first to successfully commercialize container shipping, but definitely was not the first to come up with the idea. For instance the Bureau International des Containers (BIC) was founded in 1933, 23 years before McLean would shuttle a few dozen containers from Newark to Houston on a re-purposed World War II cargo ship in 1956. Matson would soon follow, and began offering containerized freight services two years later.
Standardized Shipping Containers
Sealand (Malcom McLean's original container shipping company, now owned by Maersk) had 33' and 35' shipping containers. Matson's shipping containers were 24' long. In the late 1960's the International Organization for Standardization (commonly referred to as ISO) established standards for shipping container dimensions via ISO 668. Due to the standards set forth by the ISO, containers are now measured in TEU's (twenty-foot equivalent units). Today there are over 34,000,000 TEU in circulation (or roughly 20,000,000 shipping containers).

More Information About Shipping Containers
The information listed on intermodal shipping container doors is standardized so that the container can be handled at any port in the world. From the manufacturer information on the CSC plate, to the size & capacity information, to the container identification number, everything is standardized on a shipping container. Furthermore, to ensure the same equipment can safely handle the containers anywhere in the world, shipping containers are held to a very specific set of specifications and dimensions.
Safe Handling Instructions
A sticker or plate to identify such things as High Cube containers, hazardous cargo, or other such labels. High Cube shipping containers will also have yellow decals at the top of the frame on each end, to make the extended height more noticeable. High Cube containers have an outside height of 9'6" (one foot taller than standard shipping containers, which are 8'6" tall).
CSC Plate
The Convention for Safe Containers (CSC) Plate includes information on the date and location of manufacture, as well as other specifications. Learn more about the Convention for Safe Containers on the International Maritime Organization's website. And make sure to purchases CSC survey if you need to use your shipping container for export.
Locking Rods & Handles
Locking rods are bolted to the exterior of the shipping container cargo doors and frame, that seal the door tightly when twisted closed and clasped. A broken or bent locking rod can mean that a door won't seal properly. We guarantee doors will seal on every shipping container we sell, but it's always a good idea to grease the hinges and make sure the door frame is square.
Container Identification Number
Each shipping container has a unique identification number. The first three letters represent the container owner (registered with the Bureau International des Containers "BIC"), and those are followed by a "U" for dry containers, and then six more numerical digits for the unit number. The 7th number is a "check digit" used by calculating the value of each letter and number in the ID. Check your check digit with BIC.
Size and Capacity Specifications
To ensure safe handling, and stacking on ships, containers should not be loaded heavier than the weight specifications listed on the door and CSC plate. Please note, however, that local shipping weight regulations may be much lower than the maximum payload of the container. For instance, many shipping containers can handle over 65,000 lbs of cargo, but loading them that heavy would exceed FMCSA regulations.
Rubber Door Gasket
Each of the shipping container cargo doors is fully surrounded by a rubber gasket. The gasket allows the steel doors to be shut tightly to prevent both weather getting into the the container. It also helps keep cargo from spilling out if the freight shifts or pallets fail during transport. Good gaskets are essential to a cargo container being wind/water tight. Cargo door gaskets are covered by our 1-year warranty.