The general rule is that you have to give an allowance for tent capacity. That means getting a labeled size to accommodate one or two people more than the actual number of people who join a camping trip. This is to make way for all the camping equipment that you will carry, as well as meet the personal needs of the campers for leg room.
Here are some factors that you need to consider when buying military shelters:
What is the length and width of the tent? As mentioned in the general rules, you must anticipate the need for more space than you actually need. It's better to spend in a tent that gives you more space than saving in a tent that will force everyone to spend a narrow night in a small space.
How tall is the tent? The same rule applies to the height of the tent ceiling – give an allowance. The idea is to ensure that you can stand tall in a tent. If you get a very short tent so you have to crawl just to get inside, then expect to crash into something every time you wake up in the morning. However, you can only do this with larger tents, such as military tents that you can find at army surplus auctions along with other camping equipment. If you plan for smaller and simpler camping activities, then you can choose a smaller tent, but you still need to make sure you have enough space to move.
Does the tent give you enough space? In particular, you need to make sure that your tent can fit your inflatable mattress or sleeping bag when it is blown or launched. Otherwise you will be trapped without a source of comfort when you sleep in a tent.