Cooling & Heating Degree Days Calculator
Calculate cooling degree days with clear inputs, formula guidance, and practical result checks.
Cooling & Heating Degree Days measurements
Enter your values, then calculate.
Result
How to calculate cooling & heating degree days
Cooling degree days (CDD) is a measure of how much and for how long outdoor temperature was above a reference point (commonly 65°F), used to estimate cooling energy demand over a period.
How the calculation works
CDD = Average daily temperature − Reference temperature (summed over multiple days, with negative daily values typically counted as zero).
Example
A day with an average temperature of 78°F against a 65°F reference: that day contributes 78 − 65 = 13 cooling degree days.
Frequently asked questions
Is the Cooling & Heating Degree Days Calculator free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Is my data saved when I use this calculator?
No. Calculations run entirely in your browser; nothing you enter is sent to or stored on a server.
Cooling & Heating Degree Days Calculator
CDD = Average daily temperature − Reference temperature (summed over multiple days, with negative daily values typically counted as zero).
Let's understand your cooling & heating degree days result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Cooling & Heating Degree Days
- CDD is typically summed over a billing period or season to compare cooling energy demand between periods or locations.
- Utility companies and energy modeling tools often publish CDD data for your specific location, which can be more convenient than calculating it manually.
Common Cooling & Heating Degree Days Mistakes to Avoid
- Including negative daily values (days cooler than the reference temperature) as negative numbers in the sum, when they're conventionally counted as zero contribution to cooling demand.
When to Use This Calculator
Cooling degree days (CDD) is a measure of how much and for how long outdoor temperature was above a reference point (commonly 65°F), used to estimate cooling energy demand over a period.