Pick a species/class preset (editable gal/head/day), multiply by head, optionally apply a heat multiplier, and compare to tank gallons for days of supply.
Use this when sizing tanks, haul schedules, or well demand for a group of cattle, horses, sheep, or goats.
Defaults are typical planning ranges — lactation, high salt diets, and extreme heat can push intake well above the preset.
Herd gal/day = head x gal/head/day x heat multiplier. Days of supply = tank gallons / herd gal/day.
gal_day = head x gpd x heat_mult
days_supply = tank_gal / gal_day
Presets are planning defaults, not veterinary requirements. Pair with the stock tank volume calculator for tank_gal.
40 beef cows x 15 gal x 1.0 = 600 gal/day. A 500-gal tank → ≈ 0.83 days of supply (refill more than once daily).
Same herd at 1.3x heat → 780 gal/day.
Assumptions: constant daily demand; tank is usable gallons to the outlet.
Limits: frozen water, broken floats, and shared wildlife use are not modeled.
Responsibility: animals without water are an emergency — verify troughs daily in heat.
Lactating dairy, finishers, and work horses often drink more than the rough default.
Run once per group and add gal/day totals.
Lush pasture reduces free-water need; dry hay and salt raise it.
Many operations want at least 1 day of storage at peak demand — more if power or wells are unreliable.