Constant-temperature degree days (DD) calculator

Multiply a constant positive temperature difference by days; periods on the other side of the base contribute zero.

Units

\mathrm{DD} = \text{Positive temperature difference} \times \text{Days}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

\mathrm{DD} = 18 \times 12 = 216

Symbol	Meaning	Unit
$\mathrm{DD}$	heating or cooling degree days	°F·day
$\text{Positive temperature difference}$	difference from the specified base	°F
$\text{Days}$	constant-temperature duration	day

Symbol	Meaning	Unit
$\mathrm{DD}$	heating or cooling degree days	K·day
$\text{Positive temperature difference}$	difference from the specified base	K
$\text{Days}$	constant-temperature duration	day

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.