Other questions have tried to address how big/small towns have to be in order to function, but I'm more interested in approaching it from a different angle: How big would a town have to be to support a given population?
Firstly, let me just clarify that by "town" I really just mean a place where people live, and not implying any arbitrary population cutoffs (as opposed to a village or a city).
For the purposes of this question, let's assume medieval era farming techniques and knowledge. Let's also assume that the town in question can do trade, but trade is infrequent enough (or the town poor enough) that while they could get the occasional tools or a new seed stock, they cannot rely on trade for essential things like supplementing their food supplies.
Given this, and assuming a reasonable variety of crops given the era, how large a plot could a farmer farm? (For bonus points, how much food, and what kinds, would he be producing here?) How much could that be increased by hired hands? For self-sufficiency, how many people would be needed to support this farmer (blacksmiths to make/repair his tools, carpenters to build his house, etc.)? How would this scale if we add a second farmer and plot? That is, do we have to have twice the number of blacksmiths and carpenters, or can a single "set" support multiple farmers?
I hope this one's not growing too broad; the gist is that I'm trying to find a way to determine population size based on the number of farms/farmers, or going the other way to find out how many farms/farmers I'd need to have, given a specific population. And, consequently, what the physical size of the town would be, including said farms.