Conex dimensions follow one global rule. Every standard container is 8 feet wide, 8 feet 6 inches tall, and either 20 or 40 feet long.
This guide shows the exact conex box dimensions, a quick conex size chart, and simple tips to pick the right size.
Table of Contents
What Is a Conex Box? Standard Conex Size Explained
What is a conex box?
It is a steel shipping container. “CONEX” stands for Container Express, a name the U.S. military used in the 1950s.
The first military boxes were small, about 8.5 feet long. Today, the word “conex” means any modern ISO shipping container. “Connex box” is just another spelling.
What is the standard size of a conex?
The standard conex is 20 ft × 8 ft × 8 ft 6 in (6.06 × 2.44 × 2.59 m). The 40 ft version is the other common choice.
What is a 20 ft container?
It is the smaller standard unit. It counts as one TEU (twenty-foot equivalent unit), the basic measure of container capacity. A 40 ft box counts as two.
The sizes come from ISO 668, the global standard for series 1 freight containers. This is why a box built in one country fits ships, trains and trucks in every other.
Conex Dimensions Size Chart: 20 ft, 40 ft and High Cube
Here is a simple shipping container size chart for the sizes sold in the USA. Figures are typical, since makers vary by an inch or two.
| Container | Exterior (L × W × H) | Interior (L × W × H) | Door Opening (W × H) | Volume |
|---|---|---|---|---|
| 10 ft | 10′ × 8′ × 8’6″ | 9’3″ × 7’8″ × 7’10” | 7’7″ × 7’6″ | ~560 cu ft |
| 20 ft | 20′ × 8′ × 8’6″ | 19’4″ × 7’8″ × 7’10” | 7’8″ × 7’6″ | ~1,170 cu ft |
| 20 ft High Cube | 20′ × 8′ × 9’6″ | 19’4″ × 7’8″ × 8’10” | 7’8″ × 8’5″ | ~1,300 cu ft |
| 40 ft | 40′ × 8′ × 8’6″ | 39’5″ × 7’8″ × 7’10” | 7’8″ × 7’6″ | ~2,390 cu ft |
| 40 ft High Cube | 40′ × 8′ × 9’6″ | 39’5″ × 7’8″ × 8’10” | 7’8″ × 8’5″ | ~2,700 cu ft |
| 45 ft High Cube | 45′ × 8′ × 9’6″ | 44’4″ × 7’8″ × 8’10” | 7’8″ × 8’5″ | ~3,040 cu ft |
Why is the inside smaller than the outside? The steel walls, floor and roof take up space. Expect about 4 inches lost in width and 8 inches lost in height. ISO 668 lists the outside sizes. The inside sizes come from ISO 1496, which is the guiding document for them.
Weight facts:
- A 20 ft container weighs about 4,900 lb empty (the tare weight). It carries a payload near 48,000 lb.
- A 40 ft container weighs about 8,400 lb empty. It carries a payload near 58,800 lb.
- High cube boxes weigh a little more than standard ones.
What is a high cube container? It is one foot taller. The outside height is 9 ft 6 in, and the inside height is about 8 ft 10 in. That adds roughly 12–13% more volume.
High cube is a smart pick for tall machines, deep shelving, and container conversions. The extra height leaves room for insulation, wiring and an air conditioner. A standard box is fine for plain storage, and it costs less.
Quick tip: Always measure the actual unit. Dents, flooring and door gear can change the usable space.
When planning a Conex container conversion into a comfortable office, break room, or living space, choosing the right seating layout can make a big difference in comfort and space efficiency. Explore these banquette seating dimensions and space-planning tips to understand standard seat heights, depths, and clearances for a functional interior.
20 ft vs 40 ft Conex Container: Size Differences
Length, space and price. Width and height stay the same.
| Feature | 20 ft Conex | 40 ft Conex |
|---|---|---|
| Floor area | ~150 sq ft | ~300 sq ft |
| Volume | ~1,170 cu ft | ~2,390 cu ft |
| Standard pallets | ~10 | ~20 |
| Empty weight | ~4,900 lb | ~8,400 lb |
| Best for | Tools, small stock, a site office | Large stock, workshops, multi-room builds |
What size is a 20ft container?
About the size of a single parking space, or roughly 160 sq ft of floor.
What are the dimensions of a 20 ft conex?
Outside: 20′ × 8′ × 8’6″. Inside: about 19’4″ × 7’8″ × 7’10”.
What are the dimensions of a 40 ft conex box?
Outside: 40′ × 8′ × 8’6″. Inside: about 39’5″ × 7’8″ × 7’10”.
Delivery matters too. A 20 ft box fits on a standard flatbed or tilt-bed truck. A 40 ft box needs a longer truck and wider turning room. Check your gate, driveway and overhead lines first.
Cost note: A 40 ft box costs more up front, but the price per cubic foot is usually lower. That only pays off if you will use the space.
How to Choose the Right Conex Size for Your Project
Follow these steps. Each takes a few minutes.
- Define the job. Storage, shipping, office or workshop? Each needs a different amount of space.
- Measure your cargo. Check volume and weight. Plan to fill only about 85–90% of the inside, so you can load safely.
- Check your site. Measure the ground, the truck route and the drop-off spot. Allow clear space around the doors.
- Plan for conversions. Wall insulation and framing shrink the interior. A 40 ft high cube often ends up near 280–300 sq ft of usable floor.
- Prep the ground. Use a level base such as gravel, concrete blocks or a slab. This keeps the doors working and stops rust.
- Check local rules. Many cities and counties require permits or follow zoning limits, especially for offices or homes.
- Pick the grade. One-trip boxes are near-new. Cargo-worthy boxes are safe for shipping. Wind and watertight boxes suit storage and cost less.
- Think ahead. Containers can be stacked or joined side by side to make larger spaces. Choose one size to keep plans simple.
Not sure which fits? Share your use, site size and budget with a container supplier. They can match you to the right box and quote delivery.
FAQs
What is the standard size of a conex?
The standard conex is 20 ft long, 8 ft wide and 8 ft 6 in tall (6.06 × 2.44 × 2.59 m). The 40 ft model uses the same width and height.
What are the dimensions of a 40 ft conex box?
Outside: 40′ × 8′ × 8’6″. Inside: about 39’5″ × 7’8″ × 7’10”. It holds roughly 2,390 cubic feet. A high cube adds one foot of height.
What are the dimensions of a 20 ft conex?
Outside: 20′ × 8′ × 8’6″. Inside: about 19’4″ × 7’8″ × 7’10”. It holds roughly 1,170 cubic feet, with a door opening near 7’8″ × 7’6″.
What size is a 20ft container?
It is 20 feet long, 8 feet wide and 8 feet 6 inches tall on the outside. That gives about 150 sq ft of floor space inside.
What is the difference between a 20ft and 40ft container?
A 40 ft container is twice as long. It holds about twice the volume and weight. Width and height stay the same.
What is a 20 ft container?
It is the smaller standard ISO shipping container, equal to one TEU. People use it for storage, shipping, and small offices or workshops.
Conclusion
Conex dimensions are simple: 8 ft wide, 8’6″ or 9’6″ tall, and 20 or 40 ft long. Pick the length for your space needs, and pick high cube if you need extra height.
Measurement Researcher, Size Comparison Writer & Content Specialist
Timmy Ahad is a dedicated content writer and research specialist at SizesVisualizer.com, where he focuses on creating accurate, easy-to-understand content about measurements, dimensions, size comparisons, and real-world object visualization.
