All four backyard chicken calculators
Coop size, ventilation, feed amount, brooder heat — sourced math for the questions a backyard flock keeper actually runs into. Every calculator surfaces its inputs, assumptions, and where the published guidance ends and HatchMath methodology begins.
Coop ventilation calculator
Open →Total vent area for a backyard coop, split between high outlets and low intakes, adjusted for climate and breed weight class.
Primary output
Sq ft + sq inches of vent area as a range
Sourcing posture
Principle anchored on OSU EC-1644 + UMN. Numerical sizing (1:10 ratio, climate multipliers, high/low split) is HatchMath methodology, labeled as such.
Brooder heat lamp wattage calculator
Open →Target temperature at chick level by week of life, plus an advisory wattage range. Temperature-led — thermometer reading and chick behavior are the only signals that confirm the brooder is right.
Primary output
Target temperature 90–95°F week 1, drop 5°F per week
Sourcing posture
Schedule + 250W/80-chick scenario + 15-inch suspension floor anchored on UMN Extension. Smaller-flock wattage brackets are HatchMath methodology.
Coop size + run space calculator
Open →Indoor coop floor area + outdoor run footprint by flock count, breed weight class, climate, and daily run access. Outputs ranges across the published extension figures.
Primary output
3–5 sq ft indoor (with run access); 8–10 sq ft (confined)
Sourcing posture
Indoor floor space anchored on OSU EC-1644, UMN, Penn State, and UMD. Run space (8–12 sq ft/bird), heavy-breed, and free-range adjustments are HatchMath methodology.
Feed amount calculator
Open →Daily / weekly / monthly feed for a backyard flock, plus recommended bag size and reorder cadence. Adjusts by life stage, breed weight class, and free-range supplement percent.
Primary output
lb/day, lb/week, lb/month + 25 vs 50 lb bag pick
Sourcing posture
Layer base (100–150 g/day per hen) anchored on Alabama ANR-2913 + UMN. Life-stage multipliers + free-range cap are HatchMath methodology.
How HatchMath calculators are sourced
Every calculator shows you where its numbers come from. Tier-1 anchors are USDA, Cooperative Extension Service publications, and land-grant university poultry programs. Tier-2 are manufacturer spec sheets (Brinsea, Premier 1, feed mills) for equipment-specific numbers. When a calculator's output rule isn't directly extension-sourced — the 1:10 ventilation ratio, run-space ranges, life-stage feed multipliers, smaller-flock wattage brackets — it's labeled HatchMath methodologyin both the calculator UI and the methodology page. We never borrow extension authority for a number extension didn't publish.
For the full sourcing tier model and per-calculator formula documentation, see the methodology page. For the editorial standards (review cadence, AI policy, corrections), see the editorial policy.