Use degree days to summarize heating or cooling demand relative to an explicitly selected base temperature over a consistent observation period.

Daily high temperatures

Required list input.

Daily low temperatures

Required list input.

Base temperature

Required number input.

Temperature unit

Required string input.

Sum daily heating degree days as max(base − (high + low) / 2, 0) without rounding daily means. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Heating degree days

The resulting heating degree days returned as a number.

Daily degree days

The resulting daily degree days returned as a list.

Degree-day unit

The resulting degree-day unit returned as a string.

• Degree days depend on base temperature, daily aggregation method, station exposure, missing observations, indoor gains, building behavior, humidity, wind, and occupancy. They are weather indices rather than direct energy predictions.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Use local quality-controlled observations, document the method and base, and calibrate energy models against actual consumption.

• Cooling Degree Days Calculator

  Sum daily cooling degree days as max((high + low) / 2 − base, 0) without rounding daily means.

• Growing Degree Days Calculator

  Accumulate growing degree days from daily high and low temperatures after clipping both observations to caller-selected lower and upper thresholds.

• Eye Height Estimate

  Find the vertical eye opening at the sampling instant as the minimum high level minus the maximum low level; a negative value means overlapping level distributions.