Trying to figure out which Conex box size is right for you? You’re not alone. Whether you’re storing equipment, shipping freight, or setting up a mobile office, choosing the right Conex box size is one of the first (and most important) decisions you’ll make.
But with multiple size options out there, and each one serving a different kind of job, it’s easy to get overwhelmed.
The good news? Once you understand how Conex box sizing works and what each size is best used for, narrowing it down becomes much easier.
In this guide, we’ll cover the most popular Conex box sizes, their common applications, and how to choose the best one for your needs.
Related: Shipping Container Sizes Chart: Compare Dimensions
What Is a Conex Box?
A Conex box is a large, reusable steel shipping container originally used for transporting goods across oceans and railways. Today, these containers are used for a lot more than shipping. Think construction site storage, portable offices, workshops, pop-up shops, and more.
They’re known for being:
- Durable and weather-resistant
- Stackable and secure
- Available in standardized sizes
When people refer to a “Conex box,” they usually mean the same thing as a shipping container or storage container. But “Conex” specifically refers to the military term for “Container Express,” which became shorthand for these steel boxes in general.
Most Common Conex Box Sizes
Let’s break down the most popular Conex box sizes you’ll see on the market today:
10-Foot Conex Box Size
Dimensions (approx.):
- Exterior: 10’ L x 8’ W x 8’6” H
- Interior: 9’5” L x 7’8” W x 7’10” H
- Cubic capacity: ~560 cu. ft.
Best for:
- Residential storage
- Small equipment or tools
- Tight spaces (backyards, alleys, small job sites)
Why choose it:
This is a great compact option when space is limited but you still need a secure, weatherproof container. It’s easy to deliver, move, and position. Even in urban or residential areas.
20-Foot Conex Box Size (Standard)
Dimensions (approx.):
- Exterior: 20’ L x 8’ W x 8’6” H
- Interior: 19’4” L x 7’8” W x 7’10” H
- Cubic capacity: ~1,170 cu. ft.
Best for:
- Job site storage
- Moving and transport
- Equipment and inventory storage
Why choose it:
This is the most popular Conex box size by far. It’s compact enough for most spaces, but big enough to handle heavy-duty needs. It also fits on most standard delivery trucks without requiring special permits.
Related: 20 Foot Shipping Containers
40-Foot Conex Box Size (Standard)
Dimensions (approx.):
- Exterior: 40’ L x 8’ W x 8’6” H
- Interior: 39’5” L x 7’8” W x 7’10” H
- Cubic capacity: ~2,385 cu. ft.
Best for:
- Warehousing and large-scale storage
- Long-distance freight shipping
- Office or modular building conversions
Why choose it:
Twice the size of a 20-footer, this container gives you max space without increasing the width. It’s a favorite for businesses with large storage needs or those converting the unit into a mobile workspace.
Related: 40 Foot Shipping Container
40-Foot High Cube Conex Box Size
Dimensions (approx.):
- Exterior: 40’ L x 8’ W x 9’6” H
- Interior: 39’5” L x 7’8” W x 8’10” H
- Cubic capacity: ~2,694 cu. ft.
Best for:
- Bulky or tall items
- Equipment with overhead clearance needs
- Conversions into tiny homes, offices, or retail spaces
Why choose it:
High cube containers give you an extra foot of height, perfect if you need to stack tall items or want more vertical room for conversions. That added cubic space goes a long way for oversized loads or comfortable interiors.
Related: How Wide is a Conex Box?
Other Conex Box Sizes You Might See
While the 10ft, 20ft, and 40ft options are the most common, some suppliers offer specialty Conex box sizes like:
- 24-foot containers: Less common but offer a middle ground between 20 and 40 feet
- 45-foot high cube containers: For extra-long loads
- Custom-cut sizes: Modified containers based on your needs
Keep in mind: not all Conex box sizes are available for every use case (buying vs. renting, local vs. international, etc.). Availability can also vary based on your location and provider.
Conex Box Size Comparison Chart
| Conex Box Size | Exterior (L x W x H) | Use Case |
|---|---|---|
| 10ft | 10′ x 8′ x 8’6″ | Small storage, tight spaces |
| 20ft | 20′ x 8′ x 8’6″ | Most popular, job sites, moves |
| 40ft | 40′ x 8′ x 8’6″ | Large storage, shipping |
| 40ft High Cube | 40′ x 8′ x 9’6″ | Tall items, container homes |
How to Choose the Right Conex Box Size
When picking a Conex box size, it helps to start with a few key questions:
What are you storing or shipping?
If you’re just stashing tools or household items, a 10ft or 20ft box might do the trick. For commercial inventory or large equipment, consider 40ft or high cube sizes.
How much space do you have on-site?
Measure your delivery space before placing an order. A 40ft Conex box needs more clearance for placement, especially if delivered on a tilt-bed truck.
Are you renting or buying?
Smaller boxes (like 10ft or 20ft) are usually easier to rent. Larger or custom-sized boxes are often better suited for buyers who plan to use them long-term.
Do you need modifications?
If you’re converting the box into an office, workshop, or tiny home, a 40-foot high cube offers the most flexibility. You’ll have room for insulation, windows, and overhead lighting.
Related: Questions to Ask Before Renting a Conex Box
Pro Tip: Check Delivery Options Before You Buy
Conex box delivery isn’t always one-size-fits-all. Larger containers may require special equipment or permits, especially in cities or areas with narrow roads.
It’s a good idea to:
- Ask your supplier about delivery requirements
- Measure your space and plan for the turning radius
- Consider site prep like gravel pads or concrete foundations
Final Thoughts on Conex Box Sizes
There’s no “one-size-fits-all” answer when it comes to Conex box sizes. The right size depends on your space, purpose, and how long you plan to use it. A 20-foot container works for most, but if you need more height or space for conversions, high cubes and 40-footers are worth the upgrade.
Still not sure? Work with a reputable supplier who can help you compare Conex box sizes and even inspect the container before purchase.
Get Matched With Conex Box Suppliers Today
Looking to buy or rent a Conex box? We make it easy.
At 360Connect, we match you with top-rated suppliers in your area who offer the sizes, conditions, and modifications you need. Just tell us what you’re looking for, and we’ll handle the rest.