How large should my fortified medieval village be?

Question

Backstory

My poor medieval people are taken from our medieval Europe (Germany to be more specific) with an entire settlement to another world (think: cut a few square kilometeres of land and paste it somewhere else).

Their new location isn't quite safe. There are lots of dangerous creatures outside, some of them weird or mythical. This and other reasons forced the people to make the village tight and defendable. I thought about a palisade, but if you have other ideas, they're also welcome. I am wondering what area will the village cover. There are fields around the village which would be nice to include inside the palisade, but it depends on the necessary length of it.

Hard data

• I assume there are around 100 people in the village, three quarters of them are working age (if you have some solid arguments against those numbers they can be slightly tweaked).
• The fields area necessary for those people and will be around 50000 square meters.
• There must be place for: a church (an old one, built before they were taken), a windmill (or another simpler structure allowing milling of flour), one or two wells to provide water (there are no rivers nearby), houses for every family, plus some spare places for unexpected situations.
• The villagers are ready to personally protect the settlement if the necessity occurs.
• Wood is easily accessible (though not without risk) from a forest nearby, but stone is quite rare and valuable.

The question itself

How much area will the village cover?

Answer 1

The area the village covers would be around 10 000 $m^2$

The Math behind it:

Assuming 5 people live an an area of 200 square meters 100 to 150 for personal cattle (like chickens) 50 to 100 for the housing. We get 4000 $m^2$ for the inhabitants lets add 300 $m^2$ for the richer inhabitants.

Plus then we need some public buildings like the church 60 on 15 meters equates to 900 $m^2$ and lets say the all other public buildings ("town" hall, landfill, storage unit,...) take another 1300 $m^2$

So now we are at 6500 $m^2$ because the village has path ways and not every building touches the other there is a 45% efficiency we land at 10 075 $m^2$.

This is of course a vague estimation of the size your village would have but somewhere from 8 000 to 13 000 $m^2$ seems plausible.

The farming fields would be way to big to be watched by only 100 people not even accounting for their own tasks they would need to fulfill while watching out.

Answer 2

100 people means that there are 20 or less houses in the village What was the average size of French families during the Middle Ages? (I presume that German households were of similar size). The houses of that era were rather small for a large family (say, 100 square meters), so doubling the number to allow for small yards, I would estimate a bare minimum area of the village at 100*2*20 = 4,000 square meters. This, however, would not allow to house any livestock bigger than chickens. 4,000 sq.m. circle has a perimeter of 224 meters, for which the villagers can easily build a palisade, a moat and a gate. They, however, would lack the manpower to build a substantial wall, even in this bare minimum estimate.

To allow for some livestock to be kept it, we need to double the house plots. This way we are having 8,000 sq.m. with the perimeter of 317 m that is still very doable.

However, this village would need fields, and protecting those fields would be a much more difficult task. Historically, only villages themselves were fenced (if fenced at all), while fields were wide open. For 100 people and medieval technology, 100,000 sq.m. looks like a low end estimate. This means a perimeter of 1,121 m, for which a palisade could be constructed, but villagers would have no way of watching and defending this perimeter.

I would suggest building a watchtower in the village, where a lookout will be posted. When he notices some danger, he will raise an alarm, and villagers would hurry back into the village and prepare to defend the palisade.