THI calculator

Temperature Humidity Index (THI) is a measure that has been used since the early 1990s. It accounts for the combined effects of environmental temperature and relative humidity and is a useful and easy way to assess the risk of heat stress.

Normally THI is used in cattle.  Cows can suffer a lot of heat stress with serious consequences on their productivity and welfare.  This happens because a large part of the energy deriving from food is used to maintain a constant body temperature and it is therefore not destined for other activities (milk production, growth, pregnancy, etc.).

We have put together this tool to help you calculate the THI in your cow housing


Simply fill in the temperature (C) and humidity (%) and the graphic shows you the current THI.  Use the chart alongside to see the impact on your cows welfare.

CowPlan THI Thermometer Image

Current measurements of THI do not really take into account air velocity at cow level, or solar radiation. We can address part of this when considering roof design (using roof lights or not), and by adding ventilation fans.  Recent research states that increased air speed of 3m/s will reduce temperature felt by the cow by 6 degrees centigrade.

Call us to discuss ways of improving ventilation in your cow housing and reducing the thermal heat index.

See more on the ventilation products we offer here:

THI and lying times table
THI and milk yield effects table

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