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Enter the number of pigs, the indoor space per pig in square feet, and the outdoor space per pig in square feet. The calculator gives the indoor area, the outdoor area, the total pen area, and the fencing length for a square pen of that total area. Use the stage table below to pick allowances: weaner pigs need far less room than finishers or sows, and a farrowing pen needs the most of all. These are planning estimates, not veterinary advice, and local rules may set minimums that override them.
A pig pen calculation starts from two allowances. Indoor area = pigs × indoor space per pig. Outdoor area = pigs × outdoor space per pig. Total pen area = indoor area + outdoor area. For a square pen, fencing length = 4 × sqrt(total area).
Worked example: 4 pigs at 8 sq ft indoors each need 32 sq ft indoors. At 50 sq ft outdoors each they need 200 sq ft outdoors. The total pen area is 232 sq ft, and a square pen of that area needs about 61 ft of fencing (4 × sqrt(232) = 60.9, rounded up). A pig pen for 2 pigs at 10 sq ft indoors and 25 sq ft outdoors is 20 sq ft indoors plus 50 sq ft outdoors, 70 sq ft in total. A pig pen for 10 pigs at 12 sq ft indoors and 50 sq ft outdoors is 120 sq ft indoors plus 500 sq ft outdoors, 620 sq ft in total.
Enter the number of pigs you keep or plan to keep. Enter the indoor space per pig in square feet for the sheltered, roofed part of the pen. Enter the outdoor space per pig in square feet for the run or yard. Press Calculate to see the indoor area, outdoor area, total pen area, and fencing for a square pen.
Try the defaults first, then adjust for the stage of your pigs using the table below. Guides also recommend adding 20 to 30 percent on top of the animal space for feeders, waterers, and a walkway for yourself, so treat the calculator total as the animal space, not the finished building size. Pig pen dimensions matter as much as area: a pen that meets the area target but is too narrow leaves no room for a dry sleeping area, a dunging area, and a feeding area to stay separate, which pigs strongly prefer.
Pig pen requirements change as pigs grow, so size for the largest stage you will house, not the size pigs arrive at:
| Pig stage | Indoor per pig | Outdoor per pig | |---|---|---| | Weaner piglets (up to about 50 lb) | 3-4 sq ft | 25 sq ft | | Grower pigs (50 to 150 lb) | 6-8 sq ft | 25-50 sq ft | | Feeder and finisher pigs (150 lb to market) | 10-12 sq ft | 50-100 sq ft | | Sow, dry or gestating | 18-24 sq ft | 50-100 sq ft | | Farrowing pen (sow plus litter) | 50-60 sq ft total | 100+ sq ft | | Boar, kept separately | 40-60 sq ft | 100+ sq ft |
A mini pig pen size or potbelly pig pen size can use the lower end of these ranges, since pet pigs are smaller than farm pigs, but they still root, wallow, and need separate sleeping and dunging areas. Pasture pigs need far more ground than yard pigs: on pasture, how many pigs per acre depends on soil, rotation, and local rules, but a common planning figure is roughly 10 to 20 pigs per acre with rotation, and one acre is 43,560 sq ft.
Pig fencing must resist rooting, pushing, and lifting. Hog panel fence sections, heavy welded wire panels about 16 ft long and 34 to 52 inches high, are the most reliable choice for small pens. Woven wire with a bottom board or buried skirt stops pigs rooting underneath. Electric fence for pigs, with one or two strands at snout height (about 6 to 12 inches), trains pigs well and suits larger paddocks, but it must be checked daily and it is not enough on its own for untrained pigs.
The fencing figure this calculator returns assumes a square pen. Add a gate allowance and extra for slopes and corners when you order materials. Never rely on a single strand of light wire: a pig that learns it can push through a fence will keep doing it, and a loose pig in a garden or on a road is a serious problem.
Pigs need a dry, draught-free shelter with deep pig pen bedding such as straw, which insulates and gives them something to nest in. The shelter should be large enough for every pig to lie down at once without piling, and it should stay dry: wet bedding causes pneumonia and skin problems fast. Clean out wet bedding regularly and keep the sleeping area separate from the dunging area, which pigs will do themselves if the pen is big enough.
A pig pen mud wallow is not a luxury: pigs cannot sweat, so they wallow to cool down and to protect their skin from sun and insects. Give pigs a shallow wallow area or a shaded mud patch in summer, plus clean drinking water at all times. A wallow is not a substitute for shade: the shelter and the wallow should both be shaded in hot weather, or pigs overheat quickly.
Pig pen cleaning is a weekly job at minimum, with wet spots removed more often. One feeder space per 3 to 4 pigs and one waterer per 10 to 15 pigs prevents bullying at feed time, and feeders and waterers should sit on a solid, level base pigs cannot tip over. Fresh water matters enormously: a pig drinks several gallons a day, and restricted water cuts growth fast.
Pig manure management turns a problem into a resource: well-composted pig manure is excellent for gardens, but fresh manure must never go straight onto food crops. Store manure away from watercourses, compost it hot, and spread it in season. A pen that smells strongly usually needs more bedding, better drainage, or fewer pigs, not air freshener.
A backyard pig pen suits pet pigs such as potbelly pigs far better than farm pigs, which quickly outgrow a suburban garden. Check local rules before buying any pig: many towns ban farm pigs, set minimum pen sizes, or require permits, and neighbours will notice smell and noise from a badly run pen long before they notice a well-run one.
Can pigs live outside in winter? Yes, pigs cope with cold well in a dry, draught-free shelter with deep straw bedding, and they grow a thicker coat in winter. They need extra feed in cold weather, ice-free water, and wind protection, but a heated barn is rarely needed for healthy adult pigs. Piglets and farrowing sows need much more protection: a farrowing pen needs a heat lamp area the sow cannot lie on, plus draught-free walls, or piglets chill quickly.
Indoor space per pig ranges from about 4 to 8 sq ft for weaners, 8 to 12 sq ft for growers, and 12 to 16 sq ft for finishers, with 20 to 25 sq ft for a sow. Outdoor run space is usually 25 to 100 sq ft per pig, depending on stage and whether pigs also graze pasture.
Multiply pigs by the indoor and outdoor allowances for their stage. For 4 pigs at 8 sq ft indoors and 50 sq ft outdoors, the pen is 232 sq ft in total. For 10 finishers at 12 sq ft indoors and 50 sq ft outdoors, it is 620 sq ft.
At 10 sq ft indoors and 25 sq ft outdoors each, 2 pigs need 20 sq ft indoors plus 50 sq ft outdoors, 70 sq ft in total, with about 34 ft of fencing for a square pen.
At the defaults of 8 sq ft indoors and 50 sq ft outdoors each, 4 pigs need 32 sq ft indoors plus 200 sq ft outdoors, 232 sq ft in total, with about 61 ft of fencing for a square pen.
Pet pigs are smaller, so use the lower end of the ranges: about 8 sq ft indoors and 25 to 50 sq ft outdoors each for an adult potbelly pig, in a pen with a dry shelter, a wallow or shade, and fencing they cannot root under.
Hog panels are the most reliable for small pens, woven wire with a bottom board or buried skirt also works, and electric fence at snout height (6 to 12 inches) suits trained pigs in larger paddocks. Never rely on a single strand of light wire.
Yes, pigs cannot sweat, so they wallow to cool down and protect their skin from sun and insects. Give pigs a shallow mud patch or wallow in summer, plus shade and clean drinking water at all times.
Straw is the classic pig bedding: it insulates, lets pigs nest, and composts well. Keep the sleeping area deep, dry, and draught-free, and remove wet bedding regularly to prevent pneumonia and skin problems.
Yes, healthy adult pigs cope with cold in a dry, draught-free shelter with deep straw bedding, extra feed, and ice-free water. Piglets and farrowing sows need much more protection, including a heat lamp area piglets can reach but the sow cannot lie on.
Remove wet spots and droppings at least weekly, and do a full bedding change whenever bedding turns damp or smelly. Pens with many pigs, or pigs on concrete, need cleaning more often than pigs on deep straw in a large pen.
On pasture with rotation, a common planning figure is roughly 10 to 20 pigs per acre, depending on soil, rainfall, and local rules. Yard pigs need far less ground than pasture pigs, but they still need the indoor and outdoor allowances in this calculator.
Pet pigs may be allowed where farm pigs are banned, but rules vary widely: check permits, minimum pen sizes, and distance from neighbours before buying. A well-run backyard pen with deep bedding, good drainage, and regular cleaning causes far fewer complaints.