Yes, but only an insulated container holds the cold. Bare steel sheds it as fast as a unit makes it, so cooling gets specced with insulation rather than bolted onto a plain box. How hard the unit has to work varies with the site, the sun, the glass and the size of the container, so those get settled first.
Set the same 20 ft box in two spots five miles apart and they will not need the same cooling. That is the first thing to understand, and it is why we will not put a unit size in writing before somebody describes where the container is going to sit.
None of that is exotic. It is just the reason a number pulled off the internet does not fit your container.
A shipping container is 14-gauge weathering steel with essentially no thermal mass in the shell. It heats up fast, it gives that heat straight back to whatever is inside it, and a bare steel box in direct sun in July gets hotter than the air outside and stays hot into the evening.
Run a cooling unit in a container like that and it never gets ahead. The unit works flat out, the interior sits somewhere disappointing, and you have bought yourself a running cost instead of a comfortable room. Insulation is not an upgrade on top of the cooling. It is the thing that makes the cooling work at all.
Our shop fits spray foam or rigid panel insulation and finishes over it. Which one suits comes down to the build rather than to one being better than the other. If a mini split is in the plan, say so while the insulation is being specced, because the two get sized against each other and against however much glass ends up in the walls.
People assume cooling replaces ventilation. It does not, and the reason is what happens when nobody is there.
Passive vents work continuously with no power and nothing to fail, including on the nights the unit is off and the container is locked. That is exactly when warm damp air inside meets cold steel and puts water on the ceiling. An insulated container with no way to exchange air has not solved that, it has moved the damp somewhere behind the finish where you cannot see it or wipe it up.
So on any build with cooling in it, the vents are part of the same spec. High vents let warm air out, low vents let cooler air in, and the exchange keeps going whether the unit is running or not.
A mini split is not a plug-in appliance you set on a shelf. It needs a circuit, which means the container needs a panel, which means the electrical rough-in and the cooling get planned together rather than one after the other.
The circuit for that unit gets built into the box in our shop, along with the panel it lands in. Energizing it is a licensed electrician's job, not ours, and permits are not something we pull. Doing the rough-in while the walls are open is straightforward. Chasing a circuit through finished walls in your yard afterwards is not.
Nothing above needs a calculation from you. It needs a description, and then our shop and your installer work from that.
Walk the spot and note roughly how many hours of direct sun it gets and from which side. Then tell us the size of the box and whether it is standard or high-cube, how many windows and doors you want and which walls they land in, what the container is for, and who is inside it for how many hours a day. Say as well whether you are buying it or renting it, since a rental build has to come back out later.
An insulated 20 ft office with two windows and a mini split shares almost nothing with a lightly insulated 40 ft workshop. That is why no cooled build gets a number until somebody here has read a description like that one.
Describe the spot, the size and the hours it gets used, and we will quote the insulation, the vents and the rough-in in writing the same day.
Same-day reply. We'll send a real number, a real delivery window, and any photos we need to confirm fit.
You'll hear back from us today (or first thing tomorrow if it's late). For anything urgent, call (276) 237-6144.