Here you have answered a few questions related to the tents capacity in general and the capacity of various specific tents sizes.
The capacity of a modern tent is practically always determined by the number of sleeping pads that can fit on the floor of its sleeping area. This is a backpacking principle, but it is not the best criterion for the capacity of camping tents.
So how is the person capacity of tents estimated
From what I have seen in hundreds of tents reviewed in my sites, the tent capacity is determined in the following ways, dependent on the design:
1. If the tent is a single-room structure, the capacity is determined by following backpacking principle – by the number of narrow sleeping pads that can fit on the tent’s floor.
2. If the tent has separate bedroom(s) and a living room, the capacity is determined by the number of narrow sleeping pads that can fit on the floor of bedroom(s).
So in the group 1, the officially declared capacity is the maximum capacity. Such a capacity definitely makes sense when this is about backpacking tents. You need a basic shelter to protect you from the elements, but you do not want to carry unnecessary weight.
Note that such trail tents usually have one or more vestibules. So in reality they offer much more protected space than what their floor area tells you.
However, for camping tents, this capacity makes no sense, and my advise is to downgrade the official capacity by half.
In the group 2, the official capacity applies only on the bedrooms that are under an inner tent. However, such camping tents usually (but not always) have a fully protected living room with a sealed floor, etc.
So such tents can usually accommodate more people than what their official capacity suggests. Most of the camping tents on the EU market are of this type. This means, you can have a 6-person tent that can accommodate 10 or even 12 people.
One great example of this type is this Coleman Valdes Deluxe 6 XL Air BlackOut Bedroom Family Tent. It is officially for 6 people, but it has a floored space of 244.3 ft² (22.7 m²). This includes a living room of 130.8 ft² (12.15 m²), and the rest is bedrooms.
But there is also a fully closable porch with 75.3 ft² (7 m²), so the total protected space is 320 ft² (29.7 m²). The tent is a true camping castle, and it is on the EU market.
What size tent do I need for a family of 5?
If this is about tents built for the EU market, simply buy a 5 person tent. If you cannot find it, go for a 6 person tent. You will have plenty of space in both cases.
However, if this is a tent built for the US market, I can guarantee you that you need at least an 8-person tent or even better a 10-person tent. The higher official capacity the better.
This is because their official capacity practically always makes no sense, it is based on the backpacking principle, and you need a camping tent.
How big of a tent do I need for a family of 6?
Here the same applies as for the case of a family of 5, simply disregard the official capacity if this is a tent built for the US market. Go for a 10 person or 12 person tent.
How many people can sleep in a 10×12 wall tent?
The numbers in the question mean feet, so this is a tent with a base 305 x 366 cm. The floor area is 11.16 square meters.
If you use the usual backpacking principle and a pad that is 50 cm or 60 wide and 190 cm long, this would mean 7-8 person capacity. For realistic camping, you should not go for more than 5 people in this tent.
The Guide Gear 10×12 Canvas Wall Tent shown in the picture below is of that size, yet its official capacity is 12 people, and this clearly makes no sense.
How many people does a 12×12 tent sleep?
Here again the numbers mean feet, so the base of the tent is 366 x 366 cm. This means a floor area of 13.4 square meters. You could easily put 10 narrow sleeping pads on the floor, with some space to spare.
But realistically, in my view this size would be OK for up to 6-7 people. See one nice example below, this is Cabela’s Outback Lodge 8 Person Tent and its base is 12 x 12 feet.
So I hope you now have a clear picture of what tent’s capacity means. You might want to read also my text on how big a 4 person tent is as it addresses the same issue. Check also my text about setting up a tent under a tree.
Let me know if you have questions, there is a comment box below. Bookmark this site and visit it occasionally, it is all informative, with outdoors related questions from real people and with my answers. Have a nice day.