Shipping Container Sizes: 20ft, 40ft, and High Cube Compared

Size is where choosing the right shipping container starts. Three common options (the 20ft standard, the 40ft standard, and the high cube) each suit a different project, budget, and site. Here's how the dimensions stack up, what you actually get inside, and how to decide when the tape measure disagrees with your wish list.

The standard sizes, side by side

Built to the ISO standard, containers carry the same numbers everywhere you go. A 20ft unit measures 20ft long by 8ft wide by 8ft 6in tall — about 160 sq ft of floor. Keeping the same width and height, the 40ft simply doubles the length: roughly 320 sq ft in one drop. Our one-trip 20ft standard dry container is a popular new pick in that smaller footprint.

What you actually get inside

Corrugated walls and the door frame trim inches off every direction. Expect roughly 19ft 4in of length, 7ft 8in of width, and 7ft 10in of headroom inside a standard 20ft. That headroom figure is the one that catches people off guard — a standard container clears most shelving and a tall person, but racking, ductwork, or a finished ceiling eat into it fast. Weight rarely constrains storage use, since a 20ft carries far more payload than most projects will ever load into it. A specific unit's exact figures live on its listing.

The extra foot: high cube explained

Standing a foot taller than a standard container (9ft 6in against 8ft 6in), a high cube keeps an identical footprint. That extra foot clears racking, mezzanine framing, HVAC ducting, and the insulated ceiling that makes a conversion feel like an actual room. Since the footprint never changes, a high cube sits on the same pad and arrives on the same truck; what you're buying is headroom, not more real estate. 40ft lengths are where high cubes show up most often.

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Working out footprint on a real site

About the same footprint as a single parking bay is what a 20ft container takes up, while a 40ft claims two of them end to end. That's what makes parking-lot math such a quick sanity check: figure out how many bays you'd sacrifice, and you'll know what the site can realistically host. Both swing room for the doors and walking room for yourself need accounting for, so don't crowd the box against a fence to the point where the far door can't open. Factor in vertical storage too, since shelving up a high cube's walls sometimes returns more usable space than any amount of added floor area.

Conversions vs storage: different sizing rules

Storage forgives mistakes; conversions don't. For plain storage, buy whatever size holds the inventory and fits the pad, and you're done. For an office, shop, or workshop, work backwards from the finished interior instead: insulation and lining cost inches, partitions cost feet, and the high cube's extra foot becomes the difference between a ceiling you notice and one you don't. That's also why converted units are almost always high cubes — you buy the headroom once, at purchase, and there's no adding it later.

How the doors shape daily use

How you use the box changes with length, not just how much fits inside it. Since standard double cargo doors sit at one end, a 40ft unit works as deep storage: whatever goes in last comes out first, and the far end is a long walk. A 20ft (or a 40ft with a modified side door) keeps contents reachable if you'll need everything on a weekly basis. Plan the loading order the way you'd pack a moving truck, with seasonal and rare items toward the blind end and working stock nearer the doors.

Other sizes worth knowing about

10ft and 45ft units also exist industry-wide, and you'll run into both in listings elsewhere. Making the 10ft costs the manufacturer nearly as much as a 20ft would, since it's a cut-down niche box, while the 45ft adds length that few sites can actually host. Common sizes are what we list, because that's where the supply and the value are — ask if your project genuinely needs an outlier, and we'll tell you what it takes.

Let the site help you choose, not just the need

Before you decide anything, the site itself has a say: a longer unit demands a longer straight run for the delivery truck to off-load, which means a lot that easily hosts a 20ft can turn a 40ft drop into a real challenge. Start by measuring the pad, then the approach leading to it. When the site runs tight, splitting into two 20ft units can work better than one 40ft, since each is simpler to place, they can face opposite directions, and one can move later without disturbing the other. Deciding door orientation belongs in this same conversation, so settle which way the doors will face before booking the truck.

So which size fits your project?

Start with a 20ft if space or budget is tight — it fits a parking-bay-sized pad and covers most storage jobs. A 40ft high cube delivers strong value per square foot and the headroom finished interiors need if you're planning to grow into the space or modify the unit. Request a free quote and we'll match the size to your project and site.