20ft vs 40ft: choosing by what you store

Most buyers start by asking which size they need. A better first question is what you plan to store, and how you will get it in and out. The size follows from that. This guide compares the two common lengths, 20ft and 40ft, using the things people actually put inside them.

The numbers side by side

Both sizes share the same width: 8 ft outside and about 7 ft 8 in inside. Standard boxes are 8 ft 6 in tall, and high cubes are 9 ft 6 in. The difference is length.

• 20ft standard: about 19 ft 4 in long inside, 7 ft 10 in high, and 1,172 cu ft of space.
• 40ft standard: about 39 ft 5 in long inside, 7 ft 10 in high, and 2,390 cu ft of space.
• High cube versions add about one foot of inside height: roughly 1,320 cu ft for a 20ft and 2,694 cu ft for a 40ft.

Figures are nominal and vary a little by manufacturer, so check the spec table for the unit you order.

Start with what you store

Pallets and boxed stock

A standard US pallet is 48 in by 40 in. A 20ft container takes about 10 on the floor in a single layer, and a 40ft takes about 20. If your stock comes on pallets and you know your peak count, the choice is mostly arithmetic. Leave an aisle if you need to reach pallets at the back without moving the front ones.

Tools and small equipment

For a contractor’s tool store, a 20ft is usually enough. Shelving along both walls with a center aisle holds hand tools, power tools, fixings and consumables, and everything stays within a few steps of the door. A 40ft used for tools often ends up with a forgotten back half.

Vehicles, machinery and long items

Cars, boats, mowers, ATVs and farm implements take floor length. A 20ft box takes one car with room to walk around it. A 40ft takes two cars nose to tail, or one vehicle plus a workshop area. Long items such as pipe, lumber and ladders also favor the 40ft.

Household contents

A 20ft holds the furniture and boxes from a typical two-bedroom home. A larger home or a long renovation may need a 40ft. If you will need to reach particular items during the project, two 20ft boxes can be easier to manage than one long one.

Then look at your site

A container has to be delivered, and that is where many plans change. Both sizes arrive on a tilt-bed truck that slides the box onto the ground. The truck needs a straight, firm approach and room to pull forward as the box comes off.

• As a rough guide, allow an approach of about 3 times the container length: around 60 ft for a 20ft and around 120 ft for a 40ft.
• Allow clear width of about 12 ft and overhead clearance of about 14 to 16 ft along the route.
• The drop spot itself needs to be level and firm, with a few feet clear around the box for doors and maintenance.

On a narrow urban lot or a backyard behind a house, a 20ft is often the only size that fits. On farms, yards and open job sites, a 40ft is rarely a problem.

Cost per cubic foot

A 40ft container usually costs less than two 20ft containers, both to buy and to deliver, because it is one box on one truck. Per cubic foot of storage, the 40ft is normally the better value.

That only holds if you use the space. If half of a 40ft stands empty, the cheaper box per cubic foot is the more expensive choice in practice. Size for your realistic peak, not for the most you might ever need.

When two 20ft containers beat one 40ft

• Your site has two smaller spots rather than one long one.
• You want to separate things, such as tools in one box and materials in another, with different people holding keys.
• You may move one box to another site later.
• You need easy access to everything, and doors at the end of a 40ft are too far from the back.

Another option is a 40ft double door container, with doors at both ends. It keeps the lower cost per cubic foot and puts every item within 20 ft of a door.

Standard or high cube

Choose a high cube if you will stack high, run tall racking, store machinery with a raised cab, or insulate the box for an office or workshop. The extra foot is also useful for hay, feed and bulky goods. For low items on the floor, a standard box does the same job and is often easier to find in used grades.

A quick way to decide

1. List what you will store at the busiest time of year, and estimate pallets, vehicles or cubic feet.
2. Measure the drop spot and the route the truck will take.
3. If the 40ft fits the site and you will fill most of it, choose the 40ft.
4. If the site is tight or you need separate stores, choose a 20ft, or two.
5. Add the high cube option if height matters.

You can compare the full range on our 20ft containers and 40ft containers pages, or send us your list and a photo of your site. A specialist will suggest a size and give you a delivered price for your ZIP.