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
- Enter the number of chicks you are actually brooding, including any you expect to add.
- Set the age in weeks you want the brooder to still work at, usually five or six.
- Pick your heat source, plate or lamp.
- 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.
Related calculators
What next?
Free tools that pair well with this calculator.