How to Make Animal Pen in RimWorld (1.6) | Pen Planner + Code-Backed Build Tool

Quick Build Guide

Starter Pen Layout

Fence + Gate + Pen Marker + Hay Storage

Build fence or wall loopThe local PenMarker def only works in an enclosed area, so start with a closed perimeter.
Add one gate or doorThe game alert text explicitly says a pen needs a door or gate to admit animals.
Place pen marker insideCompProperties_AnimalPenMarker adds the Food, Animals, and Auto-cut tabs to this building.
Rope animals to the penHandlers use the RopeToPen job to bring pen animals to the assigned marker.

Fence

Fence Gate

Pen Marker

Hay Buffer

Fast answer: enclose an area, place a pen marker, rope animals in, then watch Nutrition growth versus Nutrition consumption. If consumption is higher, your pen is already on borrowed time.

Fence vs Wall vs Gate

Fence: 40 HP, 70 work, PassThroughOnly, path cost 80, and tagged as isFence=true.
■Wall: 300 HP, 135 work, Impassable, and holdsRoof=true for real barns and flyer-proof coops.
Gate: 20 HP, 500 work, open speed 1.15, holdsRoof=false, and counts as the access point for a pen.

Feeding Options

Dandelions: 0.25 nutrition per plant, 2.5 grow days, low fertility demand, great in warm pens.
Haygrass: 18 hay per tile after 7 grow days. Reliable winter reserve crop.
Hay: 0.05 nutrition each, stack limit 200, starts rotting after 60 days if badly stored.

Rope-to-Pen Troubleshooting

⚠Broken fence or held-open door keeps the pen from staying enclosed.
⚠Wrong marker or no handler means the RopeToPen job never starts.
⚠Hungry animals need more grazing, hauled hay, or a smaller herd.

Biome Pen Setups

Temperate Pasture

Big fenced graze pen, dandelions inside, and a small roofed hay patch near the gate.

Desert Barn

Compact walled yard, more hauled hay, less trust in natural grass.

Tundra Shelter

Roofed walls, animal flap, and winter math done before the first snow.

Pen Marker Dashboard

Pen Load0 total

Nutrition Growth0.0 / day

Nutrition Consumption0.0 / day

ContainmentClosed

WarningsNeed input

The local PenMarker def exposes ITab_PenFood, ITab_PenAnimals, and ITab_PenAutoCut.

Animal Feed Calculator

pen_surplus = nutrition_growth_per_day - herd_consumption_per_day if pen_surplus < 0: winter_deficit = abs(pen_surplus) * winter_days hay_needed = winter_deficit / 0.05

Nutrition growth / day Copy the green value from the pen marker Food tab.

Nutrition consumption / day Copy the red value from the same tab.

Winter days Use your real no-grazing stretch, not the whole year.

Hay already stored Local Hay nutrition is 0.05 each.

Boundary type

Biome

Door or gate held open Pen is not fully enclosed No handler assigned

Surplus / day-1.1

Winter deficit22.0

Hay needed440

Hay after winter1160

This herd runs a deficit. Stock at least 440 hay before winter and do not trust fence pens for flying birds.

Auto-Slaughter Rules

2Cows

G2Goats

10Birds

Starter rule: keep breeders small, split grow-out animals into a second pen, and let the marker’s Food tab tell you when herd growth already outran grazing.

Code Sources & Links

Open local Pen Marker def Open local Fence Gate def Open local Animal Flap def

FAQ: Animals Escaping

⚠Chickens and geese have flying animation data in 1.6. Use walls and a roofed coop.
⚠Fence-blocked animals cannot open normal doors unless roped; AnimalFlap is the exception.
⚠If the pen is unenclosed, tame roamers still wander and handlers must keep re-roping them.

Quick answer

If you only need the 90-second version: fence or wall a loop, add a gate, place a pen marker inside, and rope your farm animals to it. Then open the pen marker Food tab and compare Nutrition growth against Nutrition consumption.

Warm maps: let animals graze and seed dandelions inside the pen.
Cold maps: build a roofed barn, store hay, and assume outdoor growth goes near zero in winter.
1.6 birds: chickens, ducks, and geese are the first animals to question your fence budget.

What the local game data confirms

Thing	Local 1.6 fact	Why it matters
Pen marker	100 HP, 600 work, Food + Animals + Auto-cut tabs	This is the pen dashboard, not just a label post.
Fence	40 HP, 70 work, `PassThroughOnly`, `isFence=true`	Cheap early pen boundary, but not roof support.
Fence gate	20 HP, 500 work, open speed 1.15, `holdsRoof=false`	Good access point, bad roof support, weak in raids.
Animal flap	`roamerCanOpen=true`, 850 work, 20 HP	Use it for barns because pen animals can pass while the room still stays sheltered.
Wall	300 HP, 135 work, `Impassable`, `holdsRoof=true`	Best answer for predators, winter barns, and flying birds.
Haygrass	18 hay yield after 7 days	Main winter fodder crop when grazing will fail.
Dandelions	0.25 nutrition, 2.5 grow days, low fertility minimum	Excellent pen filler for warm grazing maps.
Hay	0.05 nutrition, stack 200, starts rotting after 60 days	Turns your winter plan into something you can count.

Why animals escape in 1.6

The local source and defs give three concrete failure modes that matter more than vague “AI bug” theories:

Fence-blocked logic is real. PathGrids.xml defines FenceBlocked, and Building_Door.cs refuses normal door use for fence-blocked animals unless they are roped or the building allows roamers to open it.
Animal flaps are special on purpose. The AnimalFlap def sets roamerCanOpen=true, which is why barn flaps work for penned animals while normal doors do not.
Unenclosed pens still wander. The local ThinkTreeDefs/Animal.xml note says tame roamers wander near a suitable pen marker 10% of the time when unenclosed.

Translation: if the pen is open, your solution is not to keep re-roping animals forever. The solution is to finish the enclosure.

Representative herd pressure from local defs

Animal	Base hunger rate	Containment note
Chicken	0.14	Has flight time + flying animation data, so fence pens are risky.
Goose	0.28	Also has flying animation data and will punish lazy coop design.
Goat	0.225	Low pressure grazer, good for smaller pens.
Cow	0.535	Heavy grazer; do winter math before herd growth spikes.
Horse	0.535	Same hunger base as cows, but usually worth keeping for caravans.
Muffalo	0.535	Cold-proof pack animal; still expensive to feed when snow arrives.

These are local Core-def hunger-rate values. For exact daily feed in your colony, trust the pen marker’s own growth and consumption numbers first.

Why does the page ask for pen-marker values instead of guessing exact nutrition from species counts?

The game already calculates the exact pen result by season, weather, reachable plants, and current stockpile. Local defs are excellent for crop yields, hunger pressure, and containment behavior, but the pen marker is still the authoritative answer for your current map. That is the right technical bar.

When should I replace fences with walls?

Use walls once predators, cold snaps, raids, or 1.6 flying birds become the real bottleneck. Local building defs show the trade clearly: walls are far stronger and support roofs; fences are cheaper and quicker but much less final.

What if colonists still refuse to rope animals to the pen?

Check the obvious blockers in order: no handler assigned, path blocked, animal forbidden, wrong pen assignment, or no valid entrance. The game alert text also reminds you that a pen needs a gate or door to admit animals at all.

Local files used

Built from local RimWorld 1.6.4633 data in Buildings_Structure.xml, Buildings_Misc.xml, Jobs_Work.xml, ThinkTreeDefs/Animal.xml, Races_Animal_ChickenGroup.xml, Races_Animal_CowGroup.xml, Plants_Cultivated_Farm.xml, Plants_Wild_Temperate.xml, Items_Resource_RawPlant.xml, PathGrids.xml, and Building_Door.cs.