Hey, so medieval agricultural land in England, at least for the early medieval period, is typically assessed in terms of productivity rather than in terms of finite geographical measurements. Before the conquest of 1066, land is typically measured in 'hides', although sulungs are common in Kent among other terms, and in Domesday, 'ploughlands' are commonly used. While 'ploughlands' remain a somewhat vague term, beyond 'the amount of land ploughable by one plough team', they're commonly thought of as being roughly analogous to the earlier 'hide'. There's no real definite measurement as to how big a 'hide' or 'ploughland' is, as this is largely dependent on the land use, intensivity of the agriculture, productivity of the soil, etc. but a very rough and ready estimate is somewhere around 120 acres.

To think about a ratio, you have to start by considering how large you'd like your settlement to be. In Domesday, settlements are assessed in 'households', which can be very roughly interpreted to be around four people. A settlement of 25 households, for example, could be expected to be somewhere around 100+ people. Settlements of over 100 households are considered to be very large, and are relatively uncommon; smaller settlements could be as small as 3 or 4 households (around 12-20 people), and may have represented either those living both figuratively and literally on the fringes of society on more marginal land, or those more entrepreneurial individuals exploiting newly-cleared land.

Your medieval peasantry falls into a fairly developed hierarchy. The largest class of peasantry in Domesday was the villeins or villagers, tenant farmers who were usually in hold of a 'virgate' or quarter of a hide/ploughland, roughly some 30 acres. Below them were the smallholders, cottagers and borderers, who on average held from 5 to 15 acres. At the top of the peasant hierarchy were the Freemen, who on average also held a virgate of land, but did so free from rents. On top of these lands, there would also be the meadows and pasture, orchards and other additional lands held by the village. Bear in mind as well the presence of a three-field crop rotation system that means only 2/3 of land would be in production at any given time, with the final third potentially in use as pasture.

For a case study, let's pick and random settlement from Domesday; Norton St Philip in the Hundred of Wellow in Somerset. In 1086, Norton St Philip had a population of 19 households: 3 villagers, 13 smallholders and 3 slaves, most likely totalling some 70-90 people. There were 10 ploughlands assessed in 1086, very roughly some 1,200 acres, worked by 3 communal plough teams and 3 belonging to the lord, Edward of Salisbury, most likely worked by the slave households. The three communal plough teams suggest that, indeed, the villagers would have held around a virgate each, and the smallholders would have held some 20 acres each, which would have made them relatively prosperous. This then leaves 3-4 ploughlands fallow. In addition, there's 20 acres of meadow and 20 of pasture for grazing the village's extensive herds of 20 cattle, 28 pigs and a flock of some 240 sheep which would have been particularly lucrative. There was also 5,000 acres of woodland, which may have been used for hunting, and a mill.

Norton St Philip actually seems to have been a fairly prosperous success story. The settlement gained a pound in value just in 1086 alone between being acquired by Edward of Salisbury and being assessed for Domesday later in the same year.