Does this apply if I only keep a couple of pigs?

Yes, but with a caveat: the Handbook's figures are a per-head share of a larger group pen, so applied directly to one or two pigs they'd produce a pen smaller than the animal itself. Where that happens this calculator shows our own estimate of the smallest pen a pig can be kept in, labelled as ours rather than a published standard.

What if my pigs are different weights?

Use the average weight of the group. If there's a wide spread, it's safer to size the pen for your heaviest pigs.

Does a pig's weight affect how much space it needs?

Yes. The National Pork Board's table scales with weight, from 1.7-2.5 sq ft per pig at 12-30 lbs up to 8 sq ft per pig from 275 lbs to market weight.

Can two pigs share a pen?

Yes — the Handbook's figures already assume group housing, which is how pigs are normally kept. They're a per-head share of a shared pen, not a private pen per pig.

How much pasture land do I need for outdoor pigs?

There's no single national figure — the Handbook's own outdoor data spans a wide range across incompatible older studies with no recommended value, since it depends heavily on soil type, forage, rainfall and rotation. Check with your local extension office or land-grant university for guidance suited to your land.

Is there a version of this for the UK?

Yes — see the UK pig pen size calculator, based on the statutory welfare code (Schedule 8) and the RSPCA Assured standard.

Pig Calculator

How much space do your pigs actually need?

Based on the National Pork Board's Swine Care Handbook, for indoor and outdoor systems.

🇬🇧 UK version/🇺🇸 US version

Standards usedNational Pork Board standardIndoor & outdoor systems

Number of pigs

Average weight (lbs)

Housing type

Floor space needed

24.0 sq ft

6.00 sq ft per pig × 4 pigs

Feed cost calculator · Water calculator · Bedding calculator · Cost of keeping calculator

What this means

A roughly square pen would be about 4.9ft × 4.9ft. Long, narrow pens work too.

If you’re building a rectangular pen, examples include: 4.9ft × 4.9ft, 3.7ft × 6.5ft, 2.7ft × 8.9ft.

Working backwards: how many pigs fit?

Floor area you have (sq ft)

There is no US federal or state law setting a minimum pen size for pigs. Figures here follow the National Pork Board’s Swine Care Handbook (2018), the industry-wide reference used in Pork Quality Assurance Plus certification. This is a group-housing allowance; for one or two pigs it can work out smaller than the pig itself, so we show our own estimate of the smallest pen a pig can be kept in (roughly the square of its length) and say so — a bare minimum, not a recommended size. This tool is a planning guide, not professional advice — check with your local extension office or veterinarian before building.

How we calculated this +

Floor space needed

Source:: National Pork Board, Swine Care Handbook (2018), Table 1
Applies to:: United States — industry standard used in Pork Quality Assurance Plus certification; no federal or state law sets a minimum
Assumption:: Ranges given for the three lighter weight bands are used at their midpoint; the three heavier bands are single published figures, used as-is.
Calculation:: Weight (lb) looked up against the six published bands, multiplied by pig count.

Why outdoor mode shows the same number

Source:: National Pork Board, Swine Care Handbook (2018), Table 1
Applies to:: United States
Assumption:: The Handbook's floor-space table is for indoor housing on partial or total slats. It publishes no separate outdoor shelter standard, and its outdoor data is drawn from several older, inconsistent studies with no recommended value.
Calculation:: No calculation. Outdoor mode reuses the indoor table as a guide for shelter size and says so, rather than presenting it as an outdoor standard. Pasture land is deliberately given no figure.

Small-group practical floor area

Source:: Allometric body-area scaling, applied to Schedule 8 para 6
Applies to:: The US and England alike — a pig's body size isn't jurisdiction-specific
Assumption:: Our calculated planning figure — not a statutory or industry-standard requirement. It's the one figure on this page not taken directly from a published table, shown here rather than presented as equally authoritative.
Calculation:: Floor area ≈ 0.041 × weight(kg)^0.67 × 1.6 clearance factor (weight converted from lb), applied to the pen as a whole, so it only changes the result for very small groups.

Sources checked: September 2026.

Rules can depend on where you live. National welfare requirements aren't the same thing as local planning, registration, nuisance or disease-control rules — check with your local authority before you build or buy.

What this means

There's no US federal or state law setting a minimum pen size for pigs, unlike the UK. In its absence the figures here follow the National Pork Board's Swine Care Handbook — the closest thing the US has to a national standard, and the reference used in Pork Quality Assurance Plus (PQA Plus) certification. It's an industry standard, not a legal requirement.

The Handbook's figures are a per-head share of a larger group pen, so for one or two pigs they can work out smaller than the pig itself. We show our own estimate of the smallest pen a pig can be kept in in that case — the same approach as the UK calculator, since a pig's body size isn't jurisdiction-specific, only the published standard is.

Outdoor pasture land is deliberately not given a headline figure: the Handbook's outdoor data spans a wide range from several older, inconsistent studies with no recommended value, so there's no defensible single number. Outdoor mode shows the indoor table as a shelter guide and points you to your local extension service for pasture land.

Technical methodology +

The source, assumption and arithmetic behind each figure are in “How we calculated this” above, and on the Sources & methodology page.

Sources checked: September 2026.

Common questions

Is there a legal minimum pen size for pigs in the US?: No. Unlike the UK, there is no US federal or state law setting a minimum pen size for pigs. The figures here follow an industry standard (the National Pork Board's Swine Care Handbook), not a legal requirement.
Does this apply if I only keep a couple of pigs?: Yes, but with a caveat: the Handbook's figures are a per-head share of a larger group pen, so for one or two pigs they can work out smaller than the pig itself. Where that happens we show our own estimate of the smallest pen a pig can be kept in, labelled as ours rather than a published standard.
What if my pigs are different weights?: Use the average weight of the group. If there's a wide spread, it's safer to size the pen for your heaviest pigs.
Does a pig's weight affect how much space it needs?: Yes. The National Pork Board's table scales with weight, from 1.7–2.5 sq ft per pig at 12–30 lbs up to 8 sq ft per pig from 275 lbs to market weight.
Can two pigs share a pen?: Yes — the Handbook's figures already assume group housing, which is how pigs are normally kept. They're a per-head share of a shared pen, not a private pen per pig.
How much pasture land do I need for outdoor pigs?: There's no single national figure — it depends heavily on soil type, forage, rainfall and rotation. Check with your local extension office or land-grant university for guidance suited to your land.
Is there a version of this for the UK?: Yes — see our UK pig pen size calculator, based on the statutory welfare code (Schedule 8) and the RSPCA Assured standard.

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Want to see what keeping pigs is actually like?

Try My Backyard — a simple interactive simulation. Adopt one, feed it, play with it, keep its bedding clean, and see how it gets on.

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