Backyard chicken calculators

HatchMath publishes calculators and short reference pages for backyard chicken keepers. Where the published guidance gives a range, the calculator shows the range. Where HatchMath synthesizes practitioner consensus into a number that isn't directly published, the page labels it HatchMath methodology and surfaces the assumption.

Backyard keepers and small-flock owners who want sourced math. Specifically: anyone deciding how big to build a coop, how much ventilation it needs, what wattage of brooder lamp to buy, how much feed to order monthly. The site doesn't publish breed shopping lists or sick-bird diagnostics — those go to a poultry vet or your county extension office. The calculators do the work; the prose supports them.

Because the verified extension working set publishes ranges — and chicken keeping varies enough by climate, breed, bedding management, and coop layout that single-answer precision would be misleading. OSU Extension EC-1644 publishes 3 sq ft per bird with run access vs 8–10 sq ft for full confinement. UMN Extension publishes 3–5 sq ft indoor. Penn State and University of Maryland publish ~2 sq ft for layer floor pens. Ranges are honest about what's actually published; single numbers would imply a precision the sources don't support.

Usually no heat lamp. Heat lamps are a real fire risk, and supplemental heat in a sealed coop can create the condensation that produces frostbite — exactly the problem most beginners think the heat lamp prevents. Current extension guidance still emphasizes cold-stress monitoring and, in some cases, supplemental heat below roughly 35°F, so the safe answer is: keep the coop dry and ventilated first, use breed- and condition-specific judgment, and never use an unsafe lamp setup. See the coop ventilation guide for the underlying physics.