When Is a Chicken Fully Grown? What Small-Scale Poultry Farmers Need to Know
/Understanding when a chicken is fully grown is essential for managing your farm’s efficiency and profitability.
Whether you’re raising broilers for meat or layers for eggs, timing their maturity affects feed costs, processing schedules, and overall flock performance.
This post covers:
When a chicken is considered fully grown
How long it takes different types of chickens to reach maturity
Whether you can buy a fully grown chicken for your operation
When Is a Chicken Fully Grown?
The answer depends on the chicken’s breed and your production goals.
Broiler Chickens
If you're raising chickens for meat, “fully grown” usually refers to when the bird reaches its target market weight.
Broilers that you’re going to cook or sell whole, you could aim for 4-4.5lbs. Birds that are getting cut up you could grow a little bigger to make them easier to part out, 5-6lbs.
1 Week - Cornish Cross
*banana for scale
8 Weeks - Cornish Cross
*banana for scale
Common broiler timelines: 4 - 4.5lb finished carcass
Cornish Cross: Fully grown at 6-7 weeks for whole birds. 8 weeks for birds to part out. These are the F-1 race cars of broiler chickens.
Red Ranger / Freedom Ranger: Fully grown at 11–12 weeks. They grow slower but are hardier and better suited to pasture.
Dual-purpose breeds: Reach suitable processing size around 15–16 weeks. But remember, if you try to be two things at once (meat + eggs), you won’t be that great at either.
Chickens kept beyond these timeframes often show slower growth, have more risk of injury or stress, and have tougher meat.
Egg-Laying Chickens
If you’re raising chickens for egg production, “fully grown” usually means the bird is mature enough to lay consistently.
Point of lay (first eggs): 16-20 weeks, depending on breed
Full adult size and peak production: 6 to 8 months
Some heritage layers, like Australorps or Orpingtons, may take a bit longer but offer a longer laying life.
How Long Until Chickens Are Fully Grown?
Here’s a quick-reference guide to typical grow-out periods for different types of broilers:
Cronish Cross vs Red Ranger Growth Comparison
Weight in Pounds is on the left, Age in Weeks is along the bottom.
Your management practices and your farm's environment matters too. Cold temperatures, inconsistent feed, old feed, overcrowding, and stress can all delay growth or reduce final weight.
Can You Buy a Fully Grown Chicken?
Yes, but it’s not commonly offered by hatcheries.
Options for acquiring mature birds:
Started Pullets: Hens that are 16–20 weeks old and just about to begin laying. Available from some regional farms or hatcheries.
Adult Layers: Occasionally offered by farms downsizing their flocks. These are usually 6+ months old.
Ready-to-process Broilers: Some small farms may sell live broilers just before processing, though most sales are pre-processed only. Buying ready-to-process broilers is rare.
Be cautious when sourcing fully grown birds. Ask about:
Health and vaccination records
Diet and housing conditions
Biosecurity or disease risks when introducing new birds to your flock
Summary: Knowing When Your Chicken Is Fully Grown
For best results, align your timeline to your breed and your business model:
Process Cornish Cross broilers at 8 weeks
Plan for 11–16 weeks with Rangers or dual-purpose birds
Expect first eggs at 20–24 weeks, with layers fully matured around 28 weeks. Production layers can start shooting out eggs around 16 weeks.
Choosing the right time to process or transition your flock not only affects your bottom line, it also improves animal welfare, soil impact, and pasture efficiency.