Brooder Size Calculator

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Space, heat and feeders for a batch of chicks

Brooder size
18 sq ft
About 5 x 5 ft
Per chick
1.5 sq ft
Brooder temp
70F
Under the heat source
Feeder space
24″
Waterers
1
1 gallon each
Heat plates
1

Brooder Planner

The same batch, week by week, from hatch day to the day they move into the coop.

Ready for the coop
Jan 3
Starter feed needed
92 lb
About 2 bags
Final brooder size
24 sq ft
Week Temp Space Feed Bedding What happens
1

Nov 8
90F 6 sq ft

0.5 per chick
4.2 lb

Chick starter, 20% protein
2 in Day one. Dip each beak in water, keep the brooder draft free and watch how the chicks group under the heat.
2

Nov 15
85F 9 sq ft

0.75 per chick
6.3 lb

Chick starter, 20% protein
2 in Feathers start on the wing tips. Add a low roost bar about 4 inches off the bedding.
3

Nov 22
80F 9 sq ft

0.75 per chick
8.4 lb

Chick starter, 20% protein
3 in Wing and tail feathers fill in. Chicks start scratching, so raise feeders slightly to cut waste.
4

Nov 29
75F 12 sq ft

1 per chick
10.5 lb

Chick starter, 20% protein
3 in Chicks perch regularly. On a warm still day, give 20 minutes outside in a covered pen.
5

Dec 6
70F 12 sq ft

1 per chick
12.6 lb

Chick starter, 20% protein
3 in Most down is gone from the back. Drop night heat and widen the brooder floor.
6

Dec 13
70F 18 sq ft

1.5 per chick
14.7 lb

Chick starter, 20% protein
4 in Nearly fully feathered. Start longer supervised outdoor time and offer a little grit with any treats.
7

Dec 20
70F 18 sq ft

1.5 per chick
16.8 lb

Chick starter, 20% protein
4 in Fully feathered. Begin heat weaning by turning the heat off in daylight hours.
8

Dec 27
70F 24 sq ft

2 per chick
18.5 lb

Chick starter, 20% protein
4 in Coop ready in mild weather. Move at dusk and keep them shut in the coop for two days.

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Last updated by the ChickenCoops.ai Editorial Team

Brooder Size Calculator: the complete guide

Chicks double in size fast, and a brooder that felt roomy on day one is crowded by week three. Crowding is what starts pasty butt, pecking and pile ups, so this calculator sizes the brooder for the age you are brooding to, not just the day the box arrives.

How the brooder size calculator works

  • Space per chick climbs with age: about half a square foot in the first two weeks, three quarters to four weeks, a full square foot to six weeks, then one and a half to two square feet until they move out.
  • Feeder space is roughly one linear inch per chick under four weeks and two inches after that, so every bird can eat without fighting.
  • One gallon waterer serves about 25 chicks. More waterers beat one big one because chicks foul them constantly.
  • Heat plates warm about 20 chicks each. A single heat lamp covers roughly 50 but gives you no temperature gradient and is a real fire risk.
  • Brooder temperature starts near 95F in week one and drops about 5F per week until it matches the outside air.

How to use it

  1. Enter the number of chicks you are actually brooding, including any you expect to add.
  2. Set the age in weeks you want the brooder to still work at, usually five or six.
  3. Pick your heat source, plate or lamp.
  4. Build to the total square footage shown, or plan a second brooder before week three.

Step by step examples

Fifteen chicks brooded to six weeks

At one square foot each that is 15 square feet, near a 4 by 4 foot box. Fifteen inches of feeder, one waterer and one heat plate.

Six chicks in a stock tank

Six square feet works to week six, so a 100 gallon stock tank is fine, but they need to be out in the coop by week seven.

Recommended values

Item Value Notes
Week 1 to 2 0.5 sq ft per chick 95F under the heat source
Week 3 to 4 0.75 sq ft per chick 85F
Week 5 to 6 1 sq ft per chick 75F
Week 7 plus 1.5 to 2 sq ft per chick Ready for the coop
Waterers 1 per 25 chicks
Heat plate capacity About 20 chicks

Common mistakes

  • Heating the whole brooder. Chicks need a warm end and a cool end so they can choose.
  • Sizing for day old chicks only and being overrun by week three.
  • Using slippery newspaper as bedding, which causes splayed leg.
  • Putting food and water directly under the heat, which keeps chicks from cooling off.

Frequently asked questions

How much space does a chick need in a brooder?

Half a square foot for the first two weeks, one square foot by six weeks, and one and a half to two square feet after that.

How long do chicks stay in the brooder?

Usually five to seven weeks, until they are fully feathered and outside temperatures stay above about 60F at night.

Is a heat plate better than a heat lamp?

Yes for most people. Plates mimic a broody hen, use less power and remove the fire risk that comes with a bulb over dry bedding.

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Written by the ChickenCoops.ai Editorial Team
Written by our team of backyard chicken keepers and community moderators, and checked against published poultry husbandry guidance and our own breed and disease datasets. This is general keeping information, not veterinary advice. Call a vet for a sick bird. Last reviewed November 8, 2026.
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