Enter the daily maximum air temperature and minimum temperature into the calculator to determine the GDU.

GDU Formula

The following formula is used to calculate growing degree units.

GDU = (DmaxT  + DminT)/2 - 50 
  • Where GDU is the growing degree units
  • DmaxT is the daily maximum temperature of the area (F)
  • DminT is the daily minimum temperature of the area (F)

To calculate the growing degree units, add the daily maximum temperature to the daily minimum temperature, divide by 2, then subtract 50 from the result.

GDU Definition

What is GDU?

GDU, also denoted GDD sometimes, is short for growing degree units. A growing degree unit is a measurement of the amount of heat corn needs to reach certain points in its growth cycle.

This can be applied to other plants and crops, but corn is the original and most common.

Example Problem

How to calculate GDU?

First, determine the maximum daily temperature. For this example problem, the maximum daily temperature is found to be 85 degrees F.

Next, determine the daily minimum temperature. In this case, the daily minimum temperature is measured to be 65 F.

Finally, calculate the growing degree units using the formula above:

GDU =(DmaxT + DminT)/2 – 50

GDU =(85 + 65)/2 – 50



What is the significance of the base temperature in the GDU formula?

The base temperature in the GDU formula, often set at 50°F, is considered the minimum temperature at which plant growth begins. Temperatures below this threshold are not conducive to growth for many crops, thus they are subtracted from the average temperature in the GDU calculation to focus on the effective growing heat units.

Can GDU calculations be applied to all types of crops?

While GDU calculations are most commonly associated with corn, they can be applied to a wide range of crops. However, the base temperature and the total GDU requirements may vary significantly between different species, reflecting their unique growth temperature thresholds and heat unit needs for development.

How can farmers use GDU information in agricultural planning?

Farmers can use GDU information to optimize planting schedules, predict harvest times, and make informed decisions about irrigation and pest management. By understanding the heat requirements of their crops and monitoring accumulated GDUs, they can better align their practices with the growth stages of the plants, potentially leading to improved yields and resource efficiency.