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Farm size calculations
 | This article was migrated from DF2014:Farm size calculations and may be inaccurate for the current version of DF (v50.15). See this page for more information. |
v50.15 · v0.47.05 This article is about the current version of DF.Note that some content may still need to be updated. |
Dwarves require approximately 2 units of food and 4 units of drink each season. Farming can produce enough crops to satisfy part or all of these requirements. However, be aware that the more and larger your farms are, the more time and effort must be accorded to their maintenance.
The math
Your dwarves can plant 1 seed per tile on each farm plot, and depending on the crop, the skill of the grower, and whether the farm plot was fertilized, each planted tile will yield a stack of 0-12 (average: 5) edible, millable, brewable, or otherwise processable plants each harvest cycle. Brewing always quintuples stack sizes; for example, a stack of cave wheats [5] is brewed into a barrel of Dwarven beer [25] at a still. Processing quarry bush plants into quarry bush leaves at a farmer's workshop also quintuples stack size, as does processing sweet pods into Dwarven syrup. Milling sweet pods into Dwarven sugar does not increase stack size. Pig tails and plump helmets grow faster than other crops, and as long as the mature plants are harvested promptly, it is not hard to grow multiple crops of either plant each season from the same plot.
| Plant Name | Active Seasons | Days Per Harvest | Harvests Per Tile Per Season | Harvests Per Tile Per Year | Average Plants Harvested Per Tile Per Year | Average Processed Food/Drink Per Tile Per Year |
|---|---|---|---|---|---|---|
| Plump helmet | 4 | 25 | 3 | 12 | 60 | 300 |
| Pig tail | 2 | 25 | 3 | 6 | 30 | 150 |
| Cave wheat | 2 | 42 | 2 | 4 | 20 | 100 |
| Sweet pod | 2 | 42 | 2 | 4 | 20 | 100 |
| Quarry bush | 3 | 42 | 2 | 6 | 30 | 150 |
| Prickle berry | 4 | 25 | 3 | 12 | 60 | 300 |
| Wild strawberry | 4 | 25 | 3 | 12 | 60 | 300 |
| Longland grass | 4 | 25 | 3 | 12 | 60 | 300 |
| Rat weed | 4 | 25 | 3 | 12 | 60 | 300 |
| Fisher berry | 4 | 25 | 3 | 12 | 60 | 300 |
| Rope reed | 4 | 25 | 3 | 12 | 60 | 300 |
| Sliver barb | 4 | 25 | 3 | 12 | 60 | 300 |
| Sun berry | 4 | 25 | 3 | 12 | 60 | 300 |
| Whip vine | 4 | 25 | 3 | 12 | 60 | 300 |
Each dwarf (age 1 year or greater) consumes 4 urists of booze and 2 urists of food per season, or 16 booze and 8 food per year. A 100 dwarf fortress (not counting infants) therefore needs 1600 booze and 800 food per year.
A single farm tile, with fertilizer, configured for 3 quarry bush seasons + 1 plump helmet season, can produce 150 units of food (quarry bush leaves, 3 seasons * 2 crops per season * 5 plants per crop * 5 leaves per plant) and 75 units of booze (plump helmet wine, 1 season * 3 crops per season * 5 plants per crop * 5 booze per plant). Another tile dedicated solely to booze can produce 300 units (plump helmet wine, as above but 4 seasons), at the expense of variety. Together, they produce 375 booze and 150 food, which is enough for 18.75 dwarves, with some booze left over. That's 9.375 dwarves per farm tile, if the tiles are split in this manner. A 100 dwarf fortress therefore could theoretically get by with about 11 tiles of farmland, if the dwarves were willing to subsist on a single type of food and booze, and did not need any clothing.
In practice, however, you want booze variety to avoid bad thoughts, and your dwarves are going to need some clothing. If you grow crops for textiles to make this clothing, that will add more farmland. This calculation also assumes you use fertilizer, which is a dubious practice given the difficulty in maintaining a steady supply of wood. Why use 11 tiles with fertilizer when you could just use 20 tiles with no fertilizer, especially when the latter would use less labor? Finally, the calculation assumes all your planters have Legendary skill, and that there are enough of them to avoid any labor shortages at planting times. This may eventually be true in a long-running fortress, but is not typical in most forts.
Approaches
Many fortresses begin with a single large farm (5x5) with plump helmets, or several smaller farms (3x3 or 1x5 are common) with a wider variety of crops. Given the small number of dwarves, a single smaller farm (2x4 or 3x3) is probably best for beginning fortresses. As the growers level up and farm yields increase the farm can be expanded and newer, smaller farms with different crops can be added to enable new growers to practice their skills. The more tiles of farm plot you have, the more growers (and harvesters) you will need.
To minimize the cost of fertilization, farm plots should ideally be one less than a multiple of 4 tiles -- ex. (1x3), (1x7), (3x5), (3x9), (5x7), (7x9)