What is a General Purpose (GP) Container?
A GP container is a General Purpose container. It’s the most common type of shipping container used for sea freight. GP containers are designed for dry cargo and are fully enclosed, with solid walls, a rigid roof, and double doors at one end.
GP containers come in two main sizes: 20-foot and 40-foot. The 20-foot version is a solid choice for heavier goods. The 40-foot version gives you more space and is better when volume matters more than weight.
Both are built to work with standard pallets. A 20-foot GP can usually hold 16 pallets stacked two high. A 40-foot container can fit about double, depending on how the load is packed.
People often call them dry containers or standard containers. They’re easy to find on most routes and suit general cargo that doesn’t need extra height or airflow.
What is a High Cube (HC) Container?
A high cube container, often marked as HQ or HC, is a taller version of the standard GP container. While both are usually 40 feet in length, the high cube adds an extra 30 centimetres of internal height. That bump in space gives you more room for bulky items or tall stacks that wouldn’t fit as easily in a regular GP.
High Cube containers are designed for dry cargo, just like GP containers. The only real difference is the extra height, which increases the total cubic capacity by about 10 to 15 percent. That extra space can make a big difference when you’re loading lightweight goods, high-stacked pallets, or large equipment that won’t fit in a standard container.
You’ll often see 40HQ listed on booking platforms. These containers are common across most sea freight routes and are a good option when your cargo volume is high but your total weight stays under the container’s limit.
GP vs HC Container Dimensions and Specs
| Specification | 40GP | 40HQ |
|---|---|---|
| External Dimensions | 12.19m × 2.44m × 2.59m (40′ × 8′ × 8′6″) | 12.19m × 2.44m × 2.89m (40′ × 8′ × 9′6″) |
| Internal Dimensions | 12.03m × 2.35m × 2.39m (39′6″ × 7′9″ × 7′10″) | 12.03m × 2.35m × 2.69m (39′6″ × 7′9″ × 8′10″) |
| Usable Volume | 67.7 CBM (2,390 cu ft) | 76.4 CBM (2,700 cu ft) |
| Max Payload | 26,760 kg (58,996 lbs) | 28,680 kg (63,230 lbs) |
| Door Height | 2.28m (7′6″) | 2.58m (8′6″) |
| Common Container Codes | 42G1, 42G2 | 45G1, 45G2 |
See detailed article on container specifications with download here
When Should You Use a High Cube Container?
A high cube container is a good fit when you’re moving cargo that takes up space but doesn’t weigh a lot. If you’re shipping foam, lightweight furniture, plastic parts, or anything bulky that isn’t heavy, the extra height can make a difference.
It also helps when your pallets are stacked high. That extra 30 centimetres of headroom gives you more flexibility, especially if you’re trying to reduce the number of containers in your booking. .
As a rough guide, if your shipment is somewhere between 70 and 75 cubic metres and stays below 28 tonnes, a high cube is often the better call. You’re getting more usable space, which can help reduce your cost per cubic metre without paying extra on weight.
When Is a Standard GP Container Better?
A general purpose container is a solid option when your cargo is heavy or dense. They’re often used for things like tiles, metal parts, building materials, or bottled goods. In cases like these, the weight fills up before the space does.
If your cargo volume is below 65 cubic metres and the weight is close to the container’s limit, then a 40GP is usually the smarter pick. There’s no need to pay for extra height if you’re not going to use it. In many cases, the extra room in a 40HC just stays empty when the container hits its weight limit early.
GP containers are also easier to find in some ports and are more commonly used on shorter routes. If your freight forwarder or depot suggests a GP option, it usually means they’ve matched your cargo needs to something more efficient.
Common Mistakes When Choosing Between GP and HC
1. Choosing HC when it’s not neededMany exporters pick a HC container thinking more space always means better value. But if your cargo is heavy, you’ll reach the weight limit before you fill the extra space. That unused volume doesn’t reduce your freight cost.
2. Ignoring weight vs volume
It’s easy to focus on size and forget about total weight. A GP container may carry less in volume, but for dense cargo like tiles or bottled goods, it often makes more sense.
3. Not checking container availability
Some ports and depots don’t always stock both types. If you book a 40GP but only 40HCs are on hand, the container might be swapped without notice. That change can affect your loading plan or costs.
4. Overlooking door height
The inside height of a high cube is greater, but the door opening is slightly smaller. If your cargo needs the full internal height, make sure it can actually fit through the doors when loading.
5. Planning based on container length only
Some shippers assume a 40GP and 40HC are interchangeable just because they’re both 40 feet long. But the stacking options and internal layout can be different, which matters when using standard pallets or tall cargo.
Container Codes and How to Identify GP and HC Containers
Every shipping container has a code stamped on the doors and sides. These codes aren’t just there for tracking. They tell you what kind of container it is, who owns it, and how it’s built. If you need to tell the difference between a standard GP and a high cube container, reading the code is one of the easiest ways to check.
Here’s how to read the codes:
1. Look for the ISO size and type code
This is usually a four-character code like 22G1, 42G1, or 45G1.
- 22G1 = 20-foot general purpose (standard height)
- 42G1 = 40-foot general purpose (high cube height)
- 45G1 = 40-foot extended length or special height (often HQ with additional modifications)
The first two numbers show the length and height:
- 2 = 20 feet
- 4 = 40 feet
- 2 (second digit) = high cube
- 0 or 2 = standard height
The letter G means it’s a dry container (general purpose), and the final number (like 1) confirms it’s built to standard specs.
2. Check for the BIC container number
Each container has a unique ID like MAEU1234567. This breaks down as:
- MAE = owner prefix (e.g. Maersk)
- U = equipment category (U = freight container)
- 123456 = serial number
- 7 = check digit (used to verify the number is valid)
You can enter this full number into a BIC check digit calculator to make sure it’s correct. It’s useful when entering container details on a Bill of Lading, packing list, or customs document.
3. Physical clues on the container
If you’re checking containers in a depot or yard, high cube containers usually:
- Have reflective tape or a small “HC” marking near the top
- Stand slightly taller than a standard GP container
- May have a different container number placement on the door frame
For safety and customs clearance, the container number and ISO code must always be visible and legible. If the markings are faded or painted over, your shipment could be delayed or refused at the border.
If you want a full breakdown of what each part of the container number means, check out our guide to shipping container numbers.
GP vs HC Container Questions
What does it mean if I get a 40HC even though I booked a 40GP?
This is called high-level substitution. It happens when depots run low on 40GP stock and offer a 40HC instead. In most cases, there’s no cost difference, and your cargo will still load the same if you don’t exceed the height limit.
Are there pallet sizes that fit better in one container than the other?
Yes. If you use Australian, Euro, or custom-size pallets, the extra height in a 40HC may allow for better stacking. Always check pallet height and whether double stacking works within the internal ceiling and door clearance. Checkout out Shipping Pallets Guide
What happens if my cargo fits in a 40HC but not through the door opening?
It’s a common issue. The internal height of a 40HC is around 2.69m, but the door height is usually closer to 2.58m. If your item is rigid or cannot be tilted, you may not be able to load it even though it technically fits. Always check both internal and door clearance.
If tilting isn’t possible, you’ll need to use a different type of container that allows for taller cargo:
- Open-Top Container – These allow you to load from above using a crane. Ideal for cargo that’s too tall for the door but still fits within standard width and length.
- Flat Rack Container – These have no side walls or roof and can handle over-height or irregularly shaped cargo loaded from the top or sides.
- Platform Container – Used for extremely oversized or heavy loads. Just a reinforced floor with no walls, ideal for specialised industrial shipments.
Try the free CBM Calculator Before You Book
Not sure if your cargo fits better in a 40GP or 40HC? Use our CBM Calculator for Seafreight to check your total volume and weight. It shows you how full your container will be, based on your packaging dimensions. You can also test different layouts across 20GP, 40GP, and 40HQ containers.
If you’re shipping goods by air, we’ve also built a separate CBM Calculator for Airfreight. It helps you compare actual weight vs dimensional weight to avoid surprise charges.
Need a refresher on container types and shipping methods? See our full guide to container sizes and shipping methods or download the full Container Specs Chart for quick reference.
These tools can help you plan smarter, reduce delays, and make better booking decisions for every shipment.
