Heating Degree Days Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 28, 2026Heating Degree Days Calculator
Estimating heating energy demand? This calculator computes daily Heating Degree Days, a standard energy analysis metric.
Average Temp = (Daily High + Daily Low) / 2
HDD = max(Base Temperature - Average Temp, 0)
Example
50┬░F high, 30┬░F low, standard 65┬░F base temperature:
Average Temp = 40.0┬░F → 25.0 heating degree days
Why 65┬░F Is the Standard Base Temperature
Heating Degree Days estimate how much heating a building likely needed on a given day, using a standard 65┬░F base temperature - below this threshold, most buildings need active heating to maintain a comfortable indoor temperature, based on historical energy industry convention.
How Utilities Use This Metric
Utilities and energy analysts sum daily HDD over a billing period or full heating season to help explain and predict heating energy consumption, and to normalize year-over-year energy usage comparisons against varying weather conditions.