Temperature-Humidity Index (Livestock)

Temperature-humidity index and heat-stress band by species, with a cooling recommendation.

Run the calculator

Example

You enter

Temperature 90
Unit F
Relative humidity (%) 60
Animal type dairy-cow
Ventilation closed

You get

THI 82.96

Details, formula, and sources

USDA-ARS THI from temperature and RH, with species-specific heat-stress band (dairy / beef / hog / poultry / horse) and a recommended cooling intervention.

THI = T_F - (0.55 - 0.0055 * RH) * (T_F - 58). Species stress bands: dairy 72/79/89/99; beef 74/80/90/99; hog 75/82/90/99; poultry 70/75/85/95; horse 72/79/89/99.

USDA-ARS livestock heat-stress publications; Kansas State University Cooperative Extension. Public domain.

usda.gov and K-State Research and Extension.

Estimate. AHJ and licensed professional govern.

Field names used by the API: temperature, unit, rh_percent, animal, ventilation, THI

Formula Same identity in F and C formsUSDA-ARS / NRC
Dairy thresholds (most cited) 72 mild / 79 moderate / 89 severe / 99 emergencyK-State Extension / Bohmanova et al.
Open vs closed ventilation open pasture provides natural cooling; effective band one step lowerengineering practice