October 13, 2026
Updated by the Velox team
When you compare portable storage containers, compare the space inside, not the size on the outside. The walls, floor and roof of every container take up room, so a number measured on the outside is always bigger than the space you can actually fill. Before you pick a company, ask for four things: the inside measurements, the inside cubic feet, the door opening and the load limit.
Why the outside number is always bigger
Cubic feet is just length × width × height. Measure a box on the outside and you are also counting the steel walls, the frame, the floor and the roof. None of that holds your stuff.
Here is our own container as an example. On the outside it is about 16 feet long, 8 feet wide and 7 feet 7 inches tall. Multiply that out and you get about 970 cubic feet. On the inside it is 15 feet 5 inches long, 7 feet 4 inches wide and 7 feet 1 inch tall, which is about 800 cubic feet. That is roughly 170 cubic feet, about one sixth of the box, that you can’t use.
That is normal. Every container loses some space to its walls. The point is to compare inside to inside.
How to spot an outside number
- Round sizes are usually outside sizes. “8 x 8 x 16” describes the box from the outside. 8 × 8 × 16 is 1,024 cubic feet, but the space inside a box that size will be smaller.
- Do the math yourself. If a company lists a cubic-feet number and the outside size, multiply the outside size. If the two numbers match, the cubic feet was measured on the outside.
- Just ask. “Is that the inside or the outside?” A good company can answer that right away.
The four numbers to ask for
| What to ask for | Why it matters | Velox container |
|---|---|---|
| Inside length, width and height | Tells you what fits and how high you can stack | 15 ft 5 in × 7 ft 4 in × 7 ft 1 in |
| Inside cubic feet | The real amount of space you can fill | About 800 cubic feet |
| Door opening | Everything has to fit through the door first | 68 in wide × 75 in tall |
| Load limit | How much weight the box can carry when it is moved loaded | 7,500 lb |
Don’t forget the door
A big inside doesn’t help if your couch can’t get through the door. Before moving day, measure your widest and tallest pieces, like a fridge, an armoire or a sectional, and check them against the door opening. Our door is 68 inches wide and 75 inches tall. If a piece is close, measure it on its side too.
Weight matters too
A container is only useful if it can be moved with your things inside. Ask what the load limit is. Ours is 7,500 pounds, and a typical loaded Velox container weighs about 3,000 to 4,000 pounds, so most households never get close. The heaviest thing people usually load is food storage. If you are storing a safe, machinery, tile or concrete, tell us first. Our weight limit guide explains how to load heavy things safely.
How many containers will you need?
One Velox container usually holds about a 1,500 square foot home, or 2 to 3 bedrooms, depending on how you pack, how much furniture you have and how long you have lived there. Our advice is simple: fill one, then order a second only if you need it.
To get a feel for the space, try our 3D container space calculator, or see what fits in one container. If you are moving a bigger house, our guide on container size for a 3-bedroom house walks through it.
Quick questions
Why do two companies list different cubic feet for boxes that look the same?
Usually one is measuring the outside and the other the inside. Ask which one it is before you compare.
Does a taller container always hold more?
Only the inside height counts. A box can look tall from the street and still lose several inches to its floor and roof.
What size is the Velox container?
About 8 feet by 16 feet on the outside. Inside, it is 15 feet 5 inches long, 7 feet 4 inches wide and 7 feet 1 inch tall, about 800 cubic feet. The door is 68 inches wide and 75 inches tall, and the load limit is 7,500 pounds.
Want help sizing your move?
Call or text (801) 362-9978 in Utah or (720) 674-8777 in Colorado and a real person will help you figure out how much space you need. Or get a free quote online.